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Dear friends of IDM,
IDM2022 is planned as an in-person conference in July 18-22, 2022. An update on COVID-related rules and measures will be published here in due time.
Registration deadline is 10 July.
The 14th conference on the identification of dark matter - IDM2022 - is organized by the Institute of high energy physics (HEPHY) in the beautiful city Vienna. The conference will take place from 18-22th of July 2022 at the Technical University Vienna (TU Wien) which is located in the very center of the city in close walking distance to Vienna’s main attractions like Karlsplatz, Stephansdom, Naschmarkt etc.
The aim of IDM is to draw a complete picture of the current knowledge of dark matter from cosmological scale down to particle physics, from accelerator searches to recent results in indirect and direct detection and to give a glance at future prospects and technological advancements on the endeavor to identify dark matter.
We warmly invite you to come and present talks or posters and to join in lively discussions covering all aspects of the study of dark matter and of the hunt to identify its nature. We particularly want to encourage the active participation of young researchers in the field and we plan to publish peer-reviewed proceedings. We also aim to give you a real experience of the city and of the surrounding by a Danube river cruise and local, traditional cuisine at the wine tavern Heuriger Fuhrgassl-Huber.
The following topics are the focus of the conference:
The conference photo can be found here.
Next edition: IDM2024
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The DAMIC-M (DArk Matter In CCDs at Modane) experiment employs thick, fully depleted Si charged-coupled devices (CCDs) to search for dark matter particles with a target exposure of 1 kg-year. A novel skipper readout implemented in the CCDs provides single electron resolution through multiple non-destructive measurements of the individual pixel charge, pushing the detection threshold to the eV-scale. DAMIC-M will advance by several orders of magnitude the exploration of the dark matter particle hypothesis, in particular of candidates pertaining to the so-called "hidden sector." A prototype, the Low Background Chamber (LBC), with 20g of low background Skipper CCDs, has been recently installed at Laboratoire Souterrain de Modane and is currently taking data. We will report the status of the DAMIC-M experiment and first results obtained with LBC commissioning data.
The DAMIC experiment employs large area, thick charge-coupled devices (CCDs) to search for the interactions of low-mass dark matter (DM) particles in the galactic halo with silicon atoms in the CCD target. The low pixel noise provides DAMIC with sensitivity to ionization signals of only a few charges, for a remarkably low energy threshold. From 2017 to 2019, DAMIC collected dark-matter search data with a seven-CCD array (40-gram target) installed in a low radiation environment in the SNOLAB underground laboratory. Results include exclusion limits on the existence of hidden-sector DM candidates and low-mass weakly interacting massive particles (WIMPs). We reported a conspicuous excess of events above our background model below 200 eV$_{\rm ee}$, whose origin remains unknown. We will present details of the background model construction, discuss sources of systematic uncertainty, and report on the deployment of skipper CCDs in DAMIC at SNOLAB to perform a more precise spectral measurement by the end of 2022.
SENSEI (Sub-Electron Noise Skipper Experimental Instrument) is the first dedicated direct-detection experiment using Skipper-CCD sensors to look for low-mass Dark Matter candidates that interact with electrons. Skipper-CCDs are able to make multiple non-destructive measurements of the pixel’s charge and use this information to reduce the readout noise to a negligible level to resolve single electrons. At the same time, these sensors record the lowest rate in silicon detectors of events containing one, two, three, or four electrons.
In this talk we present the latest results and the next steps for SENSEI after the successful commissioning of the first batch of science-grade sensors at SNOLAB.
The Oscura experiment will deploy a very-large array of novel silicon skipper Charge Coupled Devices (CCDs) to search for low-mass dark matter (DM). Skipper-CCDs deliver sub-electron readout noise for millions of pixels, providing an ideal detector for low-threshold rare event searches for DM-electron interactions. The Oscura instrument will consist of ~10 kg of skipper-CCDs and aims to achieve a total exposure of 30 kg-yr in a low background environment. Oscura will have unprecedented sensitivity to sub-GeV DM particles interacting with electrons, probing DM-electron scattering for DM masses down to ~500 keV and DM absorbed by electrons for masses down to ~1 eV. This talk will describe the Oscura experiment and the main technical challenges of the ongoing R&D effort, including engaging new foundries in the fabrication of CCDs, developing a cold readout solution, and understanding experimental backgrounds.
Direct-detection experiments searching for dark matter-nucleon interactions with a charge-based readout are commonly calibrated using sources interacting with the electron of the detector target.
But nuclear and electron interactions produce a different amount of charge for the same energy deposition.
Therefore, the precise knowledge of the nuclear recoil ionization yield is essential for nuclear recoil measurement.
In this talk, we will present the first ionization yield measurement in silicon down to an energy of 100 eV.
A silicon-based SuperCDMS HVeV cryogenic calorimetric detector was operated in a monochromatic neutron beam at the Triangle Universities Nuclear Laboratory (Durham, North Carolina) as part of the IMPACT program.
A coincidence measurement between the silicon detector and a liquid scintillator backing array selects six fixed neutron energies (from 4 keV to 100 eV).
The measured ionization yield is consistent with previous measurements above 2 keV and presents a deviation to lower yield with respect to the Lindhard model. We did not observe a ionization production threshold down to 100 eV.
For optimal sensitivity to low-mass dark matter candidates experiments
like DAMIC-M employ skipper charged-coupled devices (CCDs) with detection
threshold of just a few ionization charges. Ionization signals from
small-angle Compton scatters of environmental gamma-rays - an important
component of the background in dark matter searches – must thus be
characterized down to O(10 eV) energy. Using a Am-241 gamma-ray source,
we report a precise measurement of scattering on silicon atomic shell
electrons in a skipper CCD with single-electron resolution. Notable
differences are observed between data and theoretical expectations in the
L-shell energy region (<150 eV). We also present preliminary data from a
skipper CCD exposed to low-energy neutrons (<24 keV) from a SbBe
photoneutron source, demonstrating a measurement of the nuclear recoil
ionization efficiency in Si down to few ionization charges.
Dark showers from strongly interacting dark sectors that confine at the GeV scale can give rise to novel signatures at electron-positron colliders. In my talk, I will discuss the sensitivity of B factory experiments to dark showers produced through an effective interaction arising from a heavy off-shell mediator. I will show that a prospective search for displaced vertices at Belle II can improve the sensitivity to dark showers substantially compared to existing searches for GeV-scale long-lived particles, promptly produced resonances or single photons. Moreover, I will argue that a search for light long-lived particles at LHCb can resolve the underlying structure of the effective interaction, highlighting the complementarity of LHC and intensity frontier experiments.
As a quasi-stable electrically neutral particle which can be copiously produced, neutrons represent an interesting tool (which is comparatively under-explored) with which feeble interactions with a hidden sector particle could be observed. The HIBEAM/NNBAR experiment is planning a series of searches for neutrons in flight converting into sterile neutrons and/or anti-neutrons at the European Spallation Source in Lund, Sweden. The experiment provides an ultimate sensitivity improvement for baryon number violating processes via neutron conversions of three orders of magnitude compared to the last such search. The experiment can search for such particles via regeneration, disappearance and mediated neutron-antineutron conversions. This talk describes the experiment (the principles of the experiment, apparatus and sensitivity) and has a particular focus on searches for sterile neutrons.
The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric 0νββ experiment to reach the one-tonne mass scale. The detector, located underground at the Laboratori Nazionali del Gran Sasso in Italy, consists of 988 TeO2 crystals arranged in a compact cylindrical structure of 19 towers, operating at a base temperature of about 10 mK. After beginning its first physics data run in 2017, CUORE has since collected the largest amount of data ever acquired with a solid state detector and provided the most sensitive measurement of 0νββ decay in 130Te ever conducted.
The large exposure, sharp energy resolution, segmented structure and radio-pure environment make CUORE an ideal instrument for a wide array of searches for rare events and symmetry violations. New searches for low mass dark matter, solar axions, CPT and Lorenz violations, and refined measurements of the 2νββ spectrum in CUORE have the potential to provide new insight and constraints on extensions to the standard model complementary to other particle physics searches. In this talk, we discuss recent progress on BSM and dark matter searches in CUORE.
With its excellent energy resolution and ultra-low backgrounds, the high-purity germanium detectors in the MAJORANA DEMONSTRATOR enable several searches for beyond the Standard Model physics ranging from the primary neutrinoless double beta decay search to searches for several classes of exotic dark matter models. Many of these dark matter models predict a peaked signature in an energy spectrum, which can be clearly resolved by germanium detectors. The MAJORANA detectors were operated in a low-background shield at the Sanford Underground Research Facility, and our search utilizes the 1–100 keV region of a 37 kg-year exposure collected between May 2016 and November 2019. In this talk, I will present new experimental limits for fermionic dark matter absorption, sub-GeV dark matter 3-2 body scattering, bosonic dark matter (axionlike particles and dark photons), and keV-scale sterile neutrino dark matter.
Experiments using proton beams at high luminosity colliders and fixed-target facilities provide impressive sensitivity to new light weakly coupled degrees of freedom. We revisit the production of dark vectors and scalars via proton bremsstrahlung for a range of beam energies, including those relevant for the proposed Forward Physics Facility (FPF) at the High Luminosity LHC. In addition, we extend the application of proton bremsstrahlung to other long-lived dark sectors such as axion-like particles (ALPs) with gluon coupling and millicharged particles. In another direction, we utilize the significant neutrino flux in the forward direction at the LHC to study the electromagnetic properties of neutrinos, which serve as a probe to new physics beyond the Standard Model. In particular, we set stringent constraints on the magnetic moment, millicharge, and charge radius of tau neutrinos.
Beam dump experiments place strong constraints on the parameter space of interesting sub-GeV dark matter (DM) models. We extend the current literature, which mainly focuses on the predicted signals of scalar and fermionic DM at beam dump experiments, by considering simplified DM models where the Standard Model is extended by one vector DM candidate along with one spin-1 or spin-0 mediator. In this analysis, we determine the parameter space which gives rise to the observed thermal relic abundance and predict the sensitivity of current and future beam dump experiments (such as LDMX) in addition to other complimentary experiments on these models. We explore the effect of the DM mass, mediator mass, and couplings on these constraints, considering both on-shell and off-shell DM production.
Axionlike Particles (ALPs) can be produced in the Sun and is a viable candidate to the Cosmological Dark Matter. It can decay to two photons or interact with matter via Inverse Primakoff (IP) scattering. We identify inelastic channels to the IP-processes due to atomic excitation and ionization in additional to the elastic scattering. Their cross-sections are derived with full electromagnetic fields of atomic charge and current densities, and computed by well-benchmarked atomic many-body methods. New constraints on Axion-photon-photon coupling can be probed by current and future dark matter detectors.
Sensitivity of underground experiments searching for rare events due to dark matter or neutrino interactions is often limited by the background caused by neutrons from spontaneous fission and (alpha,n) reactions. A number of codes exist to calculate neutron yields and energy spectra due to these processes. Here we present the calculations of neutron production using the modified SOURCES4 code with recently updated cross-sections for (alpha,n) reactions and the comparison of the results with other codes and available experimental data. The cross-sections for (alpha,n) reactions in SOURCES4 have been taken from reliable experimental data where possible, complemented by the results of calculations with EMPIRE or TALYS codes where the data were scarce or unavailable.
We will also present a brief overview of low-background community activities to improve our knowledge of (alpha,n) reactions and associated neutron production.
Muon-induced neutrons can lead to potentially irreducible backgrounds in rare event search experiments. We have investigated the implication of laboratory depth on the muon induced background in a future dark matter experiment capable of reaching the so-called neutrino floor. Our simulation study focuses on a xenon-based detector with 70 tonnes of active mass, surrounded by additional veto systems plus a water shield. Two locations at the Boulby Underground Laboratory (UK) served as a case study: an experimental cavern in salt at a depth of 2850 m w.e. (similar to the location of the existing laboratory), and a deeper laboratory located in polyhalite rock at a depth of 3575 m w.e. Our results show that less than one event of cosmogenic background is likely to survive standard analysis cuts for 10 years of operation at either location. The largest background component that we identified comes from delayed neutron emission from N-17 which is produced from F-19 in the fluoropolymer components of the experiment. Our results confirm that a dark matter search with sensitivity to the neutrino floor is viable (from the point of view of cosmogenic backgrounds) in underground laboratories at these levels of rock overburden. I will present the details of the performed simulations and of the obtained results.
DarkSide-20k is a direct dark matter search experiment, that looks for Weakly Interacting Massive Particles (WIMPs) events. The detector is based on an ultrapure liquid Argon double-phase Time Projection Chamber, which will be located at Laboratori Nazionali del Gran Sasso. In the rare event search experiments (like the DarkSide case), it is crucial to keep under control any background sources. In particular, one of the most dangerous background sources are neutrons, which could induce nuclear recoils, producing a signal indistinguishable from that of the WIMPs. The strategy adopted in the DarkSide-20k experiment is to build a neutron veto detector, made of a thick plastic layer containing gadolinium, which has a high neutron capture cross section. The construction of 17 cm thick plates made of polymethylmethacrylate (PMMA) doped with a compound containing gadolinium was therefore adopted. The choice of PMMA is due to the high hydrogen content of this polymer, to moderate the neutrons. Then thermal neutrons will be captured on the gadolinium nuclei and will be revealed, exploiting the subsequent emission of an easily-detectable high energy γ ray cascade. All the components of the composite material must be screened to identify any traces of elements (such as uranium, thorium and potassium) whose descendant radioactive isotopes could affect the performance of the experiment. The screening is performed with Inductively Coupled Plasma Mass Spectrometry (ICPMS) and with germanium detectors. The DarkSide collaboration foresees two possible strategies for the realisation of gadolinium doped PMMA sheets, using two gadolinium-containing compounds: gadolinium acetylacetonate (Gd(C5H7O2)3) and gadolinium oxide (Gd2O3) in the form of nanograins. The two candidates have both positive and negative aspects: for instance the gadolinium acetylacetonate is miscible in MMA (the liquid monomer), but its synthesis on an industrial scale is quite complex and requires particular attention in each step to avoid any contamination. On the other hand, it is possible to easily find gadolinium oxide nanograins at a level of radiopurity that meets the standards required by DarkSide (this aspect has been verified through germanium screening and ICPMS). However, the nanograins are not miscible in MMA, therefore they must be treated with a suitable surfactant that prevents their sedimentation, in order to obtain pieces with a reasonably homogeneous gadolinium dispersion. The surfactant concentration must be kept under control, since each additional material represents a possible source of background. Overall, 20 tons of material are required to build the detector. The R&D projects are almost finalized: laboratory scale samples have been produced with both techniques. At the moment, tests on an industrial scale are ongoing.
The gas SF$_6$ has become of interest as a negative ion drift gas for use in directional dark matter searches. However, as for other gas targets in such searches, it is important that contamination can be removed as problems with signal detection can arise. Radon gas contamination can decay and produce unwanted background events, able to mimic genuine signals. Outgassing and gas leakage from the detector cylinder can introduce contaminants such as water, oxygen and nitrogen, which can capture interaction-produced electrons, thus suppressing signals. Many gas based rare-event physics experiments manage contamination by continuous flow and disposal of the target gas. However, SF$_6$ is the most potent greenhouse gas, making this method problematic. Therefore, an alternative method must be implemented for future SF$_6$ based experiments, where the gas is reused and recycled.
The demonstration of radon removal from SF$_6$ gas with molecular sieves (MS) was a significant advance towards an SF$_6$ filtration system. It was also found that other MS types were able to capture water, oxygen and nitrogen from SF$_6$. This makes it possible to remove both radon and air contaminants by using an MS filter mixture. Unfortunately, since commercial MS are primarily used in the petroleum industry, where having low radioactive content is not essential, commercial MS intrinsically emanate radon at levels unsuitable for ultra-sensitive rare-event physics experiments.
A method to produce low radioactive MS has been developed in Nihon University (NU). A comparison with a commercially available Sigma-Aldrich MS was made by calculating a parameter indicating the amount of radon intrinsically emanated by the MS per unit radon captured from SF$_6$. It was found that the NU developed MS (V2) emanated radon at least 98.9% less per radon captured, making it a better candidate for use in an SF$_6$ filtration system. To the author’s knowledge, these are the lowest intrinsically emanating radon-absorbing material per unit mass (activated charcoal or molecular sieves).
In this talk, we will discuss the design, construction and test results of a new MS SF$_6$ filtration setup using a custom gas handling and circulation system. The gas system utilises a Vacuum Swing Adsorption (VSA) technique, making on-site regeneration of the MS possible. The regeneration functionality enables the MS filter to be reused, allowing continuous long-term operation of the filtration setup. The gas system’s capabilities were tested with a small-scale low-pressure 100L SF$_6$ TPC detector. A long-term comparison of the detector’s performance with and without the gas system operating preliminary results are presented.
Radioactivity-induced backgrounds are one of the major sources of backgrounds for rare event search experiments like direct detection of Dark Matter, Coherent Elastic Neutrino Nucleus Scattering (CE$\nu$NS), and Neutrinoless Double Beta decay (NDBD). Measurement of these backgrounds and their reduction is crucial for these experiments. We will discuss the fabrication and performance of a newly developed annular cryogenic phonon-mediated active veto detector which allows a substantial reduction of radiogenic backgrounds. In SuperCDMS SNOLAB, three of the major backgrounds that may limit the sensitivity, are Compton scatters, surface $\beta$ decays from detector housing, and background from $^{210}$Pb recoil already existing on the detector surfaces from Radon exposure. The active veto detector hosting an inner target would eliminate almost all the backgrounds from surface $\beta$s and the $^{210}$Pb recoils and reduce the Compton background by one order of magnitude.
The active veto detector is designed in such a way that it can host an inner target detector. A germanium based $\sim$500 g active veto detector is fabricated with an outer diameter of 76 mm, inner diameter of 28 mm, and 25 mm thickness. The $\sim$10 g inner detector made of germanium is 25 mm in diameter and 4 mm in thickness. A GEANT4 based simulation is performed with the active veto and inner target detector which shows that the background rate can be reduced by 50 - 80\%. Further background reduction ($>$ 90\%) is achieved with 4$\pi$ veto coverage done by placing two germanium detectors with 76 mm diameter and 25 mm thickness at the top and bottom of the veto detector. The active veto detector assembly with 4$\pi$ coverage was placed at the MINER (Mitchell Institute Neutrino Experiment at Reactor) site. The comparison of experimental data with simulation shows excellent agreement.
The LUX-ZEPLIN (LZ) dark matter experiment consists of 7 active tonnes of liquid xenon sensitive to weakly interacting massive particles (WIMPs). Even with extensive radiopurity screening and shielding, such experiments still suffer from gamma-ray and neutron backgrounds from nearby material. Any excess detected in LZ requires a deep understanding of these backgrounds; for this purpose, we have built the Outer Detector (OD). The OD comprises of 17 tonnes of gadolinium-loaded liquid scintillator surrounding the xenon target and can efficiently tag these otherwise problematic particles, providing vital information on the radioactive environment of LZ. The OD is essential to LZ’s sensitivity and greatly increases the available xenon mass for dark matter and rare event searches. I will report on the performance of the Outer Detector in LZ’s first science run.
After many years of careful design and construction, the LUX-ZEPLIN (LZ) experiment is finally taking data. Located at the Sanford Underground Research Facility in Lead, South Dakota, LZ employs a dual-phase Time Projection Chamber to search for dark matter particles. With an active volume of 7 tonnes and a three-component veto system (xenon skin, gadolinium-loaded liquid scintillator outer detector, and an ultrapure water tank), LZ has a projected sensitivity of 1.4E-48 cm^2 for the spin-independent WIMP-nucleon cross section at 40 GeV/c^2 in 1000 live days. In this talk, I will discuss the statistical methods that LZ uses in assessing its sensitivity to physics processes. Among other topics, I will describe relevant aspects of the likelihood construction, goodness-of-fit method and the Profile Likelihood Ratio (PLR) analysis, and their application to early LZ data.
In this talk, I’ll present results from a global fit of Dirac fermion dark matter (DM) effective field theory using the GAMBIT software. We include operators up to dimension-7 that describe the interactions between gauge-singlet Dirac fermion and Standard Model quarks, gluons, and the photon. Our fit includes the latest constraints from the Planck satellite, direct and indirect detection experiments, and the LHC. For DM mass below 100 GeV, we find that it is impossible to simultaneously satisfy all constraints while maintaining EFT validity at high energies. For higher masses, large regions of parameter space exist where EFT remains valid and reproduces the observed DM abundance.
Sub-GeV thermal relic dark matter typically requires the existence of a light mediator particle. We introduce the light two-Higgs-doublet portal, illustrated by a minimal UV-complete model for sub-GeV DM with kinematically forbidden annihilations into leptons.
All new physics states in this scenario lie at or below the electroweak scale, affecting Higgs physics, the muon anomalous magnetic moment and potentially neutrino masses. Observation of radiative dark matter annihilation by future MeV gamma-ray telescopes would be key to unambiguously identify the scenario.
We propose a novel mechanism for the production of dark matter (DM) from a thermal bath, based on the idea that DM particles $\chi$ can transform heat bath particles $\psi$: $\chi \psi \to \chi \chi$. For a small initial abundance of $\chi$ this leads to an exponential growth of the DM number density, in close analogy to other familiar exponential growth processes in nature. We demonstrate that this mechanism complements freeze-in and freeze-out production in a generic way, opening new parameter space to explain the observed DM abundance. Finally, we discuss possible model realizations in the contexts of Higgs portal couplings as well as sterile neutrinos, and investigate observational prospects for such scenarios.
Feebly interacting thermal relics are promising dark matter candidates.
We introduce inelastic Dirac Dark Matter, a new model with two Dirac fermions in the MeV-GeV mass range. At feeble couplings, dark matter can depart from chemical as well as kinetic equilibrium with the Standard Model during the early stages of its evolution so that its relic abundance is not necessarily set by the well known freeze-out mechanism. The feeble couplings can also give rise to long lived particles in the dark sector. Searches for such particles at colliders and fixed-target experiments are very sensitive probes. Inelastic Dirac Dark Matter offers a new search target for existing and upcoming experiments like Belle II, ICARUS, LDMX and SeaQuest.
Relativistic protons and electrons in the extremely powerful jets of blazars may boost via elastic collisions the dark matter particles in the surroundings of the source to high energies. The blazar-boosted dark matter flux at Earth may be sizeable, larger than the flux associated with the analogous process of DM boosted by galactic cosmic rays, and relevant to access direct detection for dark matter particle masses lighter than 1 GeV both with target nuclei and/or electrons. From the null detection of a signal by XENON1T, MiniBooNE, and Borexino with nulcei (by Super-K with electrons) we have derived limits on dark matter-nucleus spin-independent and spin-dependent (dark-matter-electron) scattering cross sections which, depending on the modelization of the source, can improve on other currently available bounds for light DM candidates of one up to five orders of magnitude.
I will present an extensive study of a rather generic model of the scotogenic type, providing a solution to the dark matter problem while including radiative generation of neutrino masses. After a short introduction to the model, I will review the main dark matter phenomenology based on a Markov Chain Monte Carlo analysis. I will present the leptogenesis mechanism within the this model allowing to provide the observed baryon asymmetry. Finally, I will discuss the contributions to the anomalous magnetic moment of the muon as well as lepton flavour violation, especially their interplay with dark matter aspects.
Any dark matter spikes surrounding black holes in our Galaxy are sites of significant dark matter annihilation, leading to a potentially detectable neutrino signal. In this paper we examine $10-10^5 M_\odot$ black holes associated with dark matter spikes that formed in early minihalos and still exist in our Milky Way Galaxy today, in light of neutrino data from the ANTARES and IceCube detectors. In various regions of the sky, we determine the minimum distance away from the solar system that a dark matter spike must be in order to have not been detected as a neutrino point source for a variety of representative dark matter annihilation channels. Given these constraints on the distribution of dark matter spikes in the Galaxy, we place significant limits on the formation of the first generation of stars in early minihalos---stronger than previous limits from gamma-ray searches in Fermi Gamma-Ray Space Telescope data. The larger black holes considered in this paper may arise as the remnants of Dark Stars after the dark matter fuel is exhausted; thus neutrino observations may be used to constrain the properties of Dark Stars. The limits are particularly strong for heavier WIMPs. For WIMP masses $\sim 5 \,$TeV, we show that $< 10 \%$ of minihalos can host first stars that collapse into BHs larger than $10^3 M_\odot$.
The Edelweiss collaboration performs light Dark Matter (DM) particles searches with germanium bolometer collecting
charge and phonon signals. Thanks to the Neganov-Trofimov-Luke (NTL) effect, a RMS resolution of 4.46 electron-hole pairs
was obtained on a massive (200g) germanium detector instrumented with a NbSi Transition Edge Sensor (TES) operated underground at the Laboratoire Souterrain (LSM) de Modane.
This sensitivity made possible a search for WIMP using the Migdal effect down to 32 MeV/C² and exclude crosssections down to 10-29 cm².
It is the first measurement in cryogenic germanium with such thermal sensor, proving the high relevance of this technology.
Furthermore, such TES have shown sensitivity to out of equilibrium phonons, paving the way for EDELWEISS new experience CRYOSEL.
This is an important step in the development of Ge detectors with improved performance in the context of the EDELWEISS-SubGeV program.
The SuperCDMS SNOLAB experiment is a direct dark matter search experiment with expected world-leading sensitivity to dark matter particles with masses $\leq 10$\,GeV$/c^{2}$. Currently under construction at the SNOLAB facility in Sudbury, Canada, the experiment will have an initial payload of 24 cryogenic germanium and silicon detectors that are able to detect sub-keV energy depositions. Two types of detectors are employed, known as high voltage (HV) detectors and interleaved Z-dependent ionization and phonon (iZIP) detectors. HV detectors apply a voltage bias to amplify the ionization signal in the form of phonons in order to achieve a low energy threshold and excellent resolution. iZIP detectors measure both phonon and ionization signals in order to discriminate between electron recoils and nuclear recoils, which is important for discriminating backgrounds from signals. This presentation will provide an overview of the status of the SuperCDMS SNOLAB experiment, including its projected sensitivities.
The CRESST experiment (Cryogenic Rare Event Search with Superconducting Thermometers) is searching for nuclear recoils induced by dark matter particles in cryogenic detectors employing different target materials. With their sensitivity to energy depositions of nuclear recoils of less than 100 eV, these detectors are particularly well suited to study low mass dark matter particles. The main objective of the ongoing measurement campaign, which started in summer 2020, is to investigate the origin of an unexplained event population at very low energies (“low energy excess”) which is limiting the sensitivity of the experiment in the low mass region. We report on the status of CRESST-III and show first results from this measurement campaign. Furthermore, our plans for the future including the upgrade of the readout electronics are presented.
Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) is an experiment designed to detect the direct dark matter (DM) interactions with scintillating crystals. The experiment is situated in a low-background underground facility in Laboratori Nazionali del Gran Sasso (LNGS). CRESST employs scintillating cryogenic calorimeters to measure the recoil energy of DM-nucleus interaction. The scintillation light information helps in discrimination of backgrounds from the potential DM signals. The experiment has achieved sensitivity for recoil energies down to a few tens of eV allowing it to be one of the leading experiments to probe sub-GeV/c 2 DM masses. In the latest run, CRESST operated lithium aluminate along with the traditional calcium
tungstate as lithium showed promising potentials to study spin-dependent dark matter interactions in the above-ground test measurements done. In this contribution, the latest data obtained with lithium targets and future upgrades will be discussed.
In recent years numerous experiments have started to probe the sub-GeV dark matter (DM) mass region. In order to detect such light DM particle masses, detectors with a low energy threshold are required.
Recent developments in the growth processes of diamond crystals allow for the production of high-quality large-mass diamond detectors that can be used for astroparticle physics research purposes.
Thanks to their superior properties, diamond detectors can reach an energy threshold in the eV range when operated as cryogenic calorimeters.
In this contribution the realization of the first low-threshold cryogenic detector that uses diamond as absorber for astroparticle physics applications will be reported. Two 0.175 g CVD diamond samples, each instrumented with a W-TES have been tested. The sensors showed transitions at about 25 mK. The performance of the diamond detectors will be presented highlighting the best performing one, where an energy threshold as low as 16.8 eV could be obtained.
A new era has begun towards a direct detection of ever lighter thermal dark matter candidates. To reach ultra-low detection thresholds necessary to probe unprecedentedly low dark matter masses, novel detector designs and target material alternatives are essential. One such target material is superfluid Helium which has the potential to probe so far uncharted light Dark Matter parameter space at sub-GeV/c2 masses. The “Direct search Experiment for Light dark matter”, DELight, will be using superfluid Helium as active target, instrumented with Metallic Magnetic Calorimeters (MMCs). It is a new experiment in its planning phase which will be introduced in this presentation together with the potential dark matter reach a Helium based detector offers.
A powerful signature for confirmation of a dark matter discovery is an annual modulation in the event rate of collisions in direct detection experiments. It is however unclear how substructure within the dark matter halo might impact this signal. High resolution, hydrodynamic, galaxy simulations from the FIRE collaboration’s Latte suite are used to investigate the inherent variation of dark matter around the Solar Circle of a Milky Way-type analogue galaxy. Simulations show the baryonic back-reaction, as well as assembly history of substructures, have lasting impacts on the dark matter’s spatial and velocity distributions, creating `gusts’ of dark matter wind around the Solar Circle, potentially complicating interpretations of direct detection experiments on Earth.
The velocity distributions of dark matter are noticeably non-Maxwellian, indicative of fast-moving substructure in the solar neighbourhood, unlike traditional distributions frequently assumed in the literature. Implementing a new numerical integration technique, our work generates bespoke predictions for terrestrial underground detection, finding large uncertainties arising in the expected signals of direct detection experiments. This implies that some metrics for annual modulation signals cannot be tightly constrained, due to the diverse nature of the intrinsic astrophysical inputs. Having developed a realistic end-to-end pipeline for studying these effects, we discuss the implications of these astrophysical variations in the dark matter distribution of the solar neighbourhood on current and future particle physics searches for dark matter.
-Lawrence et al., 2022 (submitted).
GeV-scale dark matter particles with strong coupling to baryons evade the standard direct detection limits as they are efficiently stopped in the overburden and, consequently, are not able to reach the underground detectors. On the other hand, novel direct detection bounds were found when the flux of dark matter particles boosted by interactions with cosmic rays was taken into account. We revisit these bounds paying particular attention to interactions of the relativistic dark matter particles in the Earth's crust. The effects of nuclear form factors, inelastic scattering and extra dependence of the cross sections on transferred momentum (e.g., due to presence of light mediators) were studied and were found to be crucial for answering the question as to whether the window for GeV-scale strongly interacting dark matter is closed or not.
The NUCLEUS experiments aims to perform a high-precision measurement of the coherent elastic neutrino–nucleus scattering (CEvNS) at the EdF Chooz B nuclear power plant in France. CEvNS is a unique process to study neutrino properties and to search for new physics beyond the Standard Model. CEvNS could also represent an unshieldable background for high-sensitivity dark matter experiments. NUCLEUS is based on cryogenic detectors, operated at temperature of the order of 10 mK, with nuclear-recoil energy thresholds of the order of tens eV scale. At present, the experiment is under construction. The commissioning of the full apparatus is scheduled for 2022 at the Underground Laboratory of the Technical University Munich, in preparation for the move to the reactor site.
Radon daughter decays continue to limit the sensitivity of 10 GeV — 10+ TeV direct dark matter searches, despite extensive screening programs, careful material selection and specialized radon-reduction systems. While these techniques form an essential basis for rare-event search experiments, we seek a fully-efficient event-level tag of radon daughter backgrounds. For detection instruments based on liquid xenon, a means to obtaining this lofty goal may lie in crystallizing the xenon. Then, experiments would record unique (E,x,y,z,t) signatures for the problematic nuclear decay chain steps and be able to reject beta background events. A further benefit of this approach is the expectation that crystalline xenon would exclude the ingress of emanated radon. I will present recent results on the instrumental performance of a dual-phase (crystalline/vapor) xenon time projection chamber, preliminary results on radon exclusion from the crystalline state, and a brief assessment of the promise of this technique for reaching the neutrino detection limit.
The best-motivated scenario for a sizable primordial black hole (PBH) contribution to the LIGO/Virgo binary black hole mergers invokes the QCD phase transition, which naturally enhances the probability to form PBH around the stellar mass scale. We reconsider the expected mass function associated not only to the QCD phase transition proper, but also the following particle antiparticle annihilation processes, and analyse the constraints on this scenario from a number of observations: The specific pattern in CMB anisotropies induced by accretion onto PBHs, CMB spectral distortions, gravitational wave searches, and direct counts of supermassive black holes at high redshift. We find that the scenario is not viable, unless an ad hoc mass evolution for the PBH mass function and a a cutoff in power-spectrum very close to the QCD scale are introduced by hand. The required fine-tunings thus severely question the 'naturaleness' appeal of this scenario.
Primordial black holes (PBHs) hypothetically generated in the first instants of life of the Universe are potential dark matter (DM) candidates. Focusing on PBHs masses in the range 5 x10^14g - 5 x 10^15g, we point out that the neutrinos emitted by PBHs evaporation can interact through the coherent elastic neutrino nucleus scattering (CEvNS) producing an observable signal in multi-ton DM direct detection experiments. We show that with the high exposures envisaged for the next-generation facilities, it will be possible to set bounds on the fraction of DM composed by PBHs improving the existing neutrino limits obtained with Super-Kamiokande. We also quantify to what extent a signal originating from a small fraction of DM in the form of PBHs would modify the so-called "neutrino floor"', the well known barrier towards detection of weakly interacting massive particles (WIMPs) as the dominant DM component.
Several pieces of evidence point toward the existence of Dark Matter (DM). One detection strategy is the search for self-annihilation or decay into standard model particles. We present a novel technique to constrain the DM annihilation rate and the DM decay rate by employing Earth-based detectors such as XENON1T or Borexino. While the primary goal of these detectors is either direct detection of DM or neutrino measurements, we show that they can also study indirect detection of DM. The expected sensitivity of these detectors lies several orders of magnitude below the world-leading results, but this is a complementary approach with smaller astrophysical uncertainties, which broadens the scientific goal of these experiments.
Despite great efforts to directly detect dark matter (DM), experiments so far have found no evidence. The sensitivity of direct detection of DM approaches the so-called neutrino floor below which it is hard to disentangle the DM candidate from the background neutrino. One of the promising methods of overcoming this barrier is to utilize the directional signature that both neutrino- and dark-matter-induced recoils possess. The nuclear emulsion technology is the most promising technique with nanometric resolution to disentangle the DM signal from the neutrino background. The NEWSdm experiment, located in the Gran Sasso underground laboratory in Italy, is based on novel nuclear emulsion acting both as the Weakly Interactive Massive Particle (WIMP) target and as the nanometric-accuracy tracking device. This would provide a powerful method of confirming the Galactic origin of the dark matter, thanks to the cutting-edge technology developed to readout sub-nanometric trajectories. In this talk we discuss the experiment design, its physics potential, the performance achieved in test beam measurements and the near-future plans. After the submission of a Letter of Intent, a new facility for emulsion handling was constructed in the Gran Sasso underground laboratory which is now under commissioning. A Conceptual Design Report is in preparation and will be submitted in 2022.
The development of low-background anisotropic detectors can offer a unique way to study those Dark Matter (DM) candidate particles able to induce nuclear recoils through the directionality technique. This approach is based on studying the correlation between the nuclear recoil's direction and the Earth's motion in the galactic rest frame, thanks to the anisotropic features of such detectors.
Among the anisotropic scintillators, the ZnWO$_{4}$ has unique features and is an excellent candidate for the purposes. Both the light output and the scintillation pulse shape depend on the impinging direction of heavy particles (p, $\alpha$, nuclear recoils, etc.) with respect to the crystal axes and can supply two independent modes to study the directionality and discriminate the $\gamma/\beta$ radiation.
In this talk, the measurements to study the anisotropic response of a ZnWO$_4$ scintillator to $\alpha$ particles and to nuclear recoils induced by neutron scattering are reported. The quenching factor values for nuclear recoils along different crystallographic axes have been determined for the first time in the three different nuclear recoil energies; the measured difference is at the level of 5.4 $\sigma$ of C.L. These results open the possibility to realise a realistic pioneering experiment to investigate, through directionality, the DM candidates mentioned above. A new perspective will be addressed.
The threshold displacement energy for nuclear recoils depends strongly on the direction of the recoiling nucleus with respect to the crystal lattice. Assuming that similar dependence holds for the ionization threshold for low energy nuclear recoils, we explore the consequences of the resulting directional dependence of the observable event rate in ionization detectors. For low mass dark matter, this effect leads to a daily modulation in the event rate. We discuss how this effect can be utilized to separate the DM signal from the solar neutrino background and how the structure of the modulation signal can be used to identify the type of the DM-nucleon coupling, or to extract information about the DM velocity distribution.
The last few years have seen the largest underground dark matter searches rapidly approach their purported ultimate sensitivity limit known as the neutrino floor, or increasingly, "neutrino fog". An experiment reaches the neutrino fog went it becomes so large and so sensitive that the background from the coherent scattering of astrophysical neutrinos begins to masquerade as dark matter, thereby preventing any conclusive identification of a signal. The encroachment of the neutrino fog has driven an increase in interest towards a technique which has the potential to circumvent the limit entirely: directional detection. This technique aims to measure the strongly anisotropic angular distribution of the dark matter wind incident on Earth as we journey around the Milky Way galaxy. While in practice directional detectors are several years away from being at a competitive scale, there are several promising approaches under investigation. In this talk I will first overview the status of neutrino backgrounds to DM searches and put a slightly new spin on the idea of the neutrino fog. I will then describe various approaches for dealing with the neutrino fog, with a particular emphasis on directional detection.
Levitated optomechanics provides a novel platform to test fundamental physics. One such application provides a unique directional dark matter direct detection technique to explore alternative parameter space to that being investigated by large scale experiments deployed underground. We present first results from our experiment, capable of resolving collisions in all three dimensions, utilising nanoparticles (10^-18 kg) for composite dark matter searches in the 10 MeV – 10 GeV mass range. We detail the theoretical calculations, experimental apparatus, data analysis framework and statistical inference that we aim to use to obtain results competitive with world-leading dark matter constraints. We present sensitivity projections for our experiment, informed by an initial characterisation of relevant backgrounds. We also discuss planned future work to explore alternative dark matter models using this experiment and complimentary approaches.
We are going to present the CYGNO project for the development of a high precision optical readout gaseous TPC for directional Dark Matter search and solar neutrino spectroscopy, to be hosted at Laboratori Nazionali del Gran Sasso. CYGNO (a CYGNus TPC with Optical readout) fits into the wider context of the CYGNUS proto-collaboration, for the development of a Galactic Nuclear Recoil Observatory at the ton scale with directional sensitivity. CYGNO peculiar features are the use of sCMOS cameras and PMTs coupled to GEMs amplification of a helium-based gas mixture at atmospheric pressure, in order to achieve 3D tracking with head tail capability and background rejection down to O(keV) energy, to boost sensitivity to low WIMP masses. We will discuss the latest R&D results within the CYGNO project and the underground installation and operation of a 50 l prototype, soon to be followed by a O(1) cubic meter experiment demonstrator in 2024-2026. We will furthermore illustrate the latest results on the negative ion drift operation at atmospheric pressure within CYGNO optical readout approach, which is the aim of the ERC Consolidator Grant project INITIUM.
Directional detection is the only admitted strategy for the unambiguous identification of galactic Dark Matter (DM) even in the presence of an irreducible background as beyond the neutrino floor. The directional detection strategy relies on the simultaneous measurements of the energy and the direction of a DM-induced nuclear recoil for identification of a DM particle without ambiguity. Recoil energies must be searched in the keV-range: a WIMP typically transfers at maximum an energy lower than 10 keV/nucleon. In order to fully describe the nuclear recoil track in this low energy region, directional detectors must be sensitive to any primary charge which requires to operate at high gain (above $10^4$). However, at high gain, 3D track reconstruction can be distorted by the influence of the numerous ions produced in the avalanches.
In this talk we present the low-energy performances of MIMAC, a directional detector based on Micromegas. MIMAC is searching simultaneously for ~GeV WIMPs and for Axion-Like Particles of masses between 200 eV up to 20 keV. We describe the interplay between electrons and ions during signal formation in a Micromegas and we model the response of the detector, at high gain, thanks to a new simulation called SimuMimac that agrees with MIMAC measurements. We will derive a formula for the deconvolution of the signal induced on the Micromegas grid by the motion of the ions, and we will validate it both experimentally and by simulations. The deconvolution enables to extract the time distribution of the primary electrons cloud before the avalanche. The asymmetry of this distribution is related to the stopping power and we show that it can be used to distinguish between the head and the tail of a nuclear recoil track, a key feature of directional detectors.
Finally, we demonstrate the directional performances of the MIMAC detector in the keV-range thanks to the new possibilities offered by the deconvolution of the ionic signal. To do so, we place the detector into mono-energetic neutron fields at 27 keV and 8 keV in order to measure the scattering angle of neutron-proton interactions. We then reconstruct the neutron energy spectra, that depends on the scattering angle, and we obtain a better than 15° angular resolution. As far as we know this is the first time that a directional detector demonstrates such good performances for recoils in the keV-range, achieving the target requirements for the directional strategy of detection.
More details can be found in: https://arxiv.org/abs/2112.12469
Conventional Dark Matter (DM) detectors are approaching the limitations of the neutrino floor, however DM searches with directional sensitivity offer the potential for probing beneath this neutrino background by measuring the galactic origin of Nuclear Recoil (NR) signals. CYGNUS is a global collaboration between several research groups with the common goal of building a galactic NR observatory distributed across sites around the globe. The proposed CYGNUS detector network will consist of multiple large scale gaseous Time Projection Chambers (TPCs) filled with Helium and SF6 gas mixture up to atmospheric pressure. These detectors will be able to probe the neutrino floor parameter space with directional sensitivity.
Due to the electronegative nature of SF6, careful consideration of the detector's gain stage is required to ensure that sufficient charge amplification can be achieved. A Multi-Mesh Thick Gaseous Electron Multiplier (MMThGEM) is a unique gain stage device that provides multiple amplification stages in a single ThGEM structure by including internal meshes that span across the holes. These meshes can be biased individually to set up transfer and amplification regions in the MMThGEM device.
The internal meshes were originally introduced to reduce positive Ion BackFlow (IBF) in the device, however these meshes also inhibit the passage of desirable negative charge. The effect of varying field strength on the electron mesh transparency was investigated through a series of Garfield++ simulations studies and subsequent experimental tests. A low pressure electron drift gas, CF4, was used so that signals could be easily measured on multiple meshes across a wide range of field strengths. By considering both the electron mesh transparency and the energy resolution of an X-ray photopeak, the transmission of electrons between transfer and amplification regions was optimised. These findings are discussed along with the limitations of the work to Negative Ion Drift (NID) gases like SF6.
Gamma-ray observations have long been used to constrain the properties of dark matter (DM), with a strong focus on weakly interacting massive particles annihilating through velocity-independent processes. However, in the absence of clear-cut observational evidence for the most simple candidates, the interest in more complex DM scenarios involving a velocity-dependent cross-section has grown over the past few years. I show how to analytically evaluate the Sommerfeld-enhanced gamma-ray flux produced by DM annihilation (in both the $s$- and $p$-wave cases) from targets populated by DM subhalos. Both features (Sommerfeld enhancement and the presence of subhalos) have a crucial impact in searches for thermal DM particle candidates with masses around or beyond TeV, or scenarios with a light dark sector. I present a detailed analytical description of the phenomena at play and show how they scale with the subhalo masses and the main Sommerfeld parameters. In addition, I present the main results of the first systematic study of velocity-dependent DM annihilation in a variety of astrophysical objects, not only including the well-studied Milky Way dwarf satellite galaxies but nearby dwarf irregular galaxies and local galaxy clusters as well.
Based on arXiv:2203.16491 and arXiv:2203.16440.
WIMP dark matter is still one of the better motivated candidates and its indirect observation via the products of it annihilation entails some of the largest experimental efforts nowadays. The correct observable to describing the high-energy photon spectrum from WIMP annihilation is the semi-inclusive process $\chi\chi\to\gamma+X$. In TeV-scale dark matter scenarios, non-perturbative effects arise due to the Sommerfeld effect as well as large Sudakov double-logarithms. We have expanded existing frameworks describing semi-inclusive DM annihilation with Sommerfeld effect in the MSSM to include NLL resummation of large Sudakov double logarithms for arbitrarily mixed neutralino DM candidates. In my talk I give an overview of our EFT approach to compute the DM annihilation cross-section into photons to $\sim\mathcal{O}(5\%)$ accuracy.
We discuss the one-loop SUSY-QCD corrections to the neutralino relic density for pMSSM scenarios with light stops where we focus on stop annihilation into gluons and light quarks including Sommerfeld enhancement effects. These corrections are important as stop (co)-annihilation becomes the dominant contribution to the relic density for scenarios with a small mass difference between the neutralino and the stop which are favored by current LHC searches and consistent with the observation of a 125 GeV Higgs boson.
To allow for the efficient analytic cancellation of infrared divergences between the real and the virtual corrections, we extend the dipole formalism by Catani and Seymour to massive initial states and verify our results through comparison with the phase space slicing approach.
The corrections have been implemented in the dark matter precision tool DM@NLO and the impact of the one-loop corrections on the cosmologically favored parameter region for relevant scenarios is analyzed.
Stars whose initial mass is between approximately 150 and 240 M$_\odot$ face a fate of complete explosion in a pair instability supernova (PISN). However, by injecting energy into the star, it may be possible in some cases to avoid this fate. We outline conditions on this energy injection which can lead to the survival or incomplete explosion of the star, and we discuss how dark matter annihilations throughout a star may offer one mechanism to provide this energy. Finally, we begin to explore the range of energy conditions which may allow stars to avoid PISN.
We propose a novel model for lepton flavor and dark matter based on the SU(2)D gauge symmetry and vector-like leptons in its fundamental representations. We introduce a dark SU(2)D Higgs doublet and a Higgs bi-doublet for the mass mixing between the vector-like lepton and the lepton. As a result, the seesaw lepton masses are generated and there are sizable one-loop contributions to the muon g−2 via the SU(2)D gauge bosons and the relatively heavy vector-like lepton, as indicated in Fermilab E989. The tree-level mass mixing between the Z boson and the isospin neutral gauge boson of SU(2)D in our model accounts for the shift in the W boson mass, being consistent with Tevatron CDFII. Finally, we show that the isospin charged gauge boson of SU(2)D becomes a plausible candidate for dark matter with a small mass splitting tied up to the modified W boson mass, and there is a viable parameter space where the favored corrections to the muon g−2 and the W boson mass and the dark matter constraints are simultaneously fulfilled.
${\rm U(1)}_{L_\mu - L_\tau} \equiv {\rm U(1)}_X$ model is anomaly free within the Standard Model (SM) fermion content, and can accommodate the muon $(g-2)$ data for $M_{Z'} \sim O(10-100)$ MeV and $g_X \sim (4 - 8) \times 10^{-4}$. WIMP type thermal dark matter (DM) can be also introduced for $M_{Z'} \sim 2 M_{\rm DM}$, if DM pair annihilations into the SM particles occur only through the $s$-channel $Z'$ exchange.
In this work, we show that this tight correlation between $M_{Z'}$ and $M_{\rm DM}$ can be completely evaded both for scalar and fermionic DM, if we include the contributions from dark Higgs boson ($H_1$). Dark Higgs boson plays a crucial role in DM phenomenology, not only for generation of dark photon mass, but also opening new channels for DM pair annihilations into the finalstates involving dark Higgs boson, such as dark Higgs pair as well as $Z' Z'$ through dark Higgs exchange in the $s$-channel, and co-annihilation into $Z' H_1$ in case of inelastic DM. Thus dark Higgs boson will dissect the strong correlation $M_{Z'} \sim 2 M_{\rm DM}$, and much wider mass range is allowed for $U(1)_X$-charged complex scalar and Dirac fermion DM, still explaining the muon $(g-2)$. We consider both generic $U(1)_X$ breaking as well as ${\rm U(1)}_X \rightarrow Z_2$ (and also into $Z_3$ only for scalar DM case).
Fifteen years after the BNL measurement of the anomalous magnetic moment of the muon (g-2) which led to the famous muon g-2 anomaly, this deviation from a prediction of the Standard Model was confirmed in 2021 by the Fermilab muon g-2 experiment. The state-of-the-art Standard Model prediction and the measured values of g-2 now differ by more than 4 standard deviations. In this talk, I will discuss explanations of the g-2 anomaly in the simplest supersymmetric model, the MSSM. In order to explain the g-2 anomaly, at least some of the superpartners of the Higgs boson, the W-bosons, and the muon (neutrinos) should have masses below a few hundred GeV. This has important implications for Dark Matter explanations in the MSSM. I will discuss the physical mechanisms at work to simultaneously explain the muon g-2 anomaly in the MSSM and to provide Dark Matter candidates in the hundred GeV mass range which provide the observed relic density via standard freeze-out production, are compatible with upper limits from direct detection experiment, and null-results from LHC searches for SUSY particles. Such models can be tested by the current multi-tonne scale direct detection experiments and by upcoming data from the LHC.
Invited talk
The TESSERACT project is currently in a R&D and planning phase, funded under the DOE Dark Matter New Initiatives program, and aims to produce fully defined experiments (dubbed HeRALD and SPICE) that will explore DM mass parameter space down to 10 MeV, with upgrade paths to sub-MeV. It will be sensitive to both nuclear recoil DM (NRDM) and electron recoils (ERDM). An initial period of targeted R&D is needed to make technical choices and retire technical risks, leading to a well-defined set of design parameters with baseline values. Multiple target materials will be used, sharing identical readout. In addition to maximizing sensitivity to a variety of DM interactions, this provides an independent handle on instrumental backgrounds. The HeRALD experiment will use superfluid helium as a target material. Helium, with its light mass, has good NRDM sensitivity, but minimal sensitivity to low-mass dark photons. The SPICE experiment will use polar crystals, which will ultimately have the best sensitivity to dark photon mediated DM, but require lower energy thresholds than LHe for the same NRDM reach. Scintillating crystals such as GaAs have sensitivity to ERDM with kinetic energy greater than the electronic bandgap of the material. Both LHe and GaAs produce scintillation light as well as phonon signals, and the relative timing and signal strengths may be used to reduce both instrumental backgrounds and those due to radioactivity.
invited talk
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The Scintillating Bubble Chamber (SBC) experiment will combine the well-established liquid argon and bubble chamber technologies to search for low-mass dark matter. SBC benefits from the excellent electron-recoil insensitivity and alpha-neutron discrimination inherent in bubble chambers with the addition of energy reconstruction provided from the scintillation signal. Noble liquids can be superheated to a much greater extent than the molecular fluids used by past bubble chambers for dark matter searches while retaining insensitivity to electron recoils, translating to a targeted energy threshold of 100 eV. Two functionally-similar detectors are being built. One, under construction at Fermilab, will be used for engineering and calibration studies, and a potential measurement of the coherent elastic neutrino-nucleus scattering on argon. A low-background version for the dark matter search will be operated at SNOLAB. The status of the SBC Fermilab and SNOLAB detectors, in addition to the projected dark matter sensitivity, will be discussed.
The PICO-60 C$_3$F$_8$ dark matter detector is a bubble chamber located at SNOLAB, 2 km underground in Sudbury, Ontario, Canada using 52 kg of octafluoropropane (C$_3$F$_8$) as the target fluid. This experiment reached exposures of 1404 kg-day at a 2.45-keV thermodynamic threshold and 1167 kg-day at 3.29-keV. The physics program of PICO bubble chambers will be presented in this talk, including the most stringent direct-detection constraints to date on the WIMP-proton spin-dependent cross-section and leading limits on the couplings for photon-mediated interactions. Leading limits for dark matter masses between 2.7 GeV/c$^2$ and 24 GeV/c$^2$ will be presented for anapole moment, electric dipole moment, magnetic dipole moment, and millicharge. These couplings to the electromagnetic current through higher multipole interactions were studied using non-relativistic contact operators in an effective field theory framework.
The NEWS-G collaboration is searching for light dark matter using spherical proportional counters. Access to the mass range from 50 MeV to 10 GeV is enabled by the combination of low energy threshold, light gaseous targets (H, He, Ne), and highly radio-pure detector construction. Initial NEWS-G results obtained with SEDINE, a 60 cm in diameter spherical proportional counter operating at the Laboratoire Souterrain de Modane (France), excluded for the first time WIMP-like dark matter candidates down to masses of 500 MeV/c2.
The construction of a new, 140 cm in diameter, spherical proportional counter constructed at LSM using 4N copper with 500 um electroplated inner layer will be presented, along with its installation and commissioning at SNOLAB (Canada), where it is scheduled to collect data with an improved shielding later this year.
Furthermore, the design and construction of ECUME, a 140 cm in diameter spherical proportional counter fully electroformed underground will be discussed. The potential to achieve sensitivity reaching the neutrino floor in light Dark Matter searches with a next generation detector will be also summarised.
The NEWS-G collaboration is searching for light dark matter using spherical proportional counters. Access to the mass range from 50 MeV to 10 GeV is enabled by the combination of low energy threshold, light gaseous targets (H, He, Ne), and highly radio-pure detector construction. Initial NEWS-G results obtained with SEDINE, a 60 cm in diameter spherical proportional counter operating at the Laboratoire Souterrain de Modane (France), excluded for the first time WIMP-like dark matter candidates down to masses of 500 MeV/c2.
The NEWS-G collaboration has constructed a new, 140 cm in diameter, spherical proportional counter at LSM using 4N copper with 500 um electroplated inner layer. Prior to shipping the detector to SNOLAB, a short data-taking campaign was undertaken at LSM using methane, which provides sensitivity down to 100 MeV/c2 for spin-independent and spin-dependent dark matter nucleon interactions. To capitalise on this potential, robust calibrations of the detector response to single ionisation electrons are required, which is accomplished primarily with a UV laser and a 37Ar purpose-made gaseous source. New physics results from this run, leading to world-leading spin-dependent sensitivity will be presented. Moreover, new results in the search for Solar Kaluza-Klein axions with the SEDINE, the most recent NEWS-G measurements of neon and methane quenching factors will be presented.
DEAP-3600 is a WIMP dark matter direct detection experiment located at SNOLAB. The detector consists of a 3.3 tonne volume of liquid argon instrumented with 255 photomultipliers attached to an acrylic vessel to detect the scintillation light produced by nuclear recoils. DEAP-3600 has set world leading limits on spin-independent WIMP dark matter interactions on argon and most recently the first direct detection constraints on Planck-scale mass dark matter with multiple scatter signatures. A summary of the experiment and these results will be presented.
The DARWIN observatory is a proposed next-generation direct Dark Matter search experiment. Out of its 50t total natural xenon inventory, 40t will be inside a dual-phase Time Projection Chamber (TPC). With its unprecedented sensitivity for WIMPs down to the so-called neutrino floor, DARWIN will also serve as an observatory for rare processes such as the search for neutrinoless double beta decay, for axions and axion-like particles as well as interactions of solar neutrinos.
In this talk, we will present the general outline of DARWIN and its sensitivity in various science channels. We report on the ongoing optimisation of the setup as well as on R&D to test large scale detector components.
The Haloscope At Yale Sensitive To Axion Cold dark matter (HAYSTAC) is both a data pathfinder and an innovation test bed for the 3-12 GHz (~12.5-50 ueV) mass range. A collaboration of Yale, Colorado, Berkeley and Johns Hopkins, the experiment has pioneered the implementation of quantum-limited amplifiers and more recently a squeezed-state receiver which circumvents the standard quantum limit entirely. It has also driven the development of novel microwave cavities which are pushing up into the mass range corresponding to the post-inflation axion. Recent results will be discussed, as well as future plans for greater quantum acceleration and higher mass reach.
Spin-precession experiments are the leading efforts to detect axion dark matter interacting with nuclei. The experimental strategy is to polarize the nuclear spin in one direction with a background magnetic field and search for spin-precession induced by the oscillating axion field using a sensitive magnetometer. I revisit the experimental strategy over all hierarchies between the relevant time scales: the axion coherence time, the integration time, and the spin-relaxation time. The calculation reveals new features in how the axion interacts with nuclear magnetic resonance experiments. The results are applicable to searches for the axion coupling to nucleons, and also the coupling to gluons, which would be responsible for solving the strong CP problem.
The Taiwan Axion Search Experiment by Haloscope (TASEH) is the first axion experiment in Taiwan. Our detector system included a tunable-frequency cavity immersed in a static magnetic field of 8 Tesla and an amplifier chain with a system noise of ~ 2.2K. From the first data taken in 2021, we excluded the axion-photon coupling $|g_{a𝛾𝛾}| ≳ 8.2 × 10^{-14} GeV^{-1}$, a factor of eleven above the benchmark KSVZ model, in the axion mass range 19.4687 - 19.8436 𝝁eV. This is the first constraints on $g_{a𝛾𝛾}$ in this mass region from a haloscope-type experiment.
The Any Light Particle Search II (ALPS II) is a light-shining-through-a-wall (LSW) style experiment currently under construction at DESY in Hamburg, Germany. ALPS II will probe for axions and axion-like particles in the mass range below 0.1 meV. LSW experiments create an axion field by shining a laser through a dipolar magnetic field. The axion field then passes through a wall that blocks the laser light, and into a second region of magnetic field where a small amount of its energy is converted back into an electromagnetic field that can then be measured. ALPS II will be the first LSW experiment to employ optical cavities both before and after the wall to amplify the measured signal, requiring a sophisticated optical system to do so. With a magnet string capable of producing two 106 m long regions of 5.3 T magnetic fields, optical cavities each over 120 m in length, and an input laser capable of providing 50 W, ALPS II seeks to achieve a final sensitivity in the axion-electromagnetic coupling constant of $g_{a\gamma\gamma}=2\times10^{-11}$GeV$^{-1}$. This will allow the experiment to investigate a region of the parameter space where anomalies in stellar cooling rates and observations of high energy photons hint at the existence of axions or axion-like particles. Operation of both the magnet string at full current and the laser system at full power was demonstrated earlier this year. A 246 m test cavity, whose fields traverse the magnet string, has been built and is being used to commission the optical system. In addition to this, a heterodyne detection system is currently being implemented for an axion-search scheduled for later in the year, while a second independent detection system, using a transition edge sensor, is under development. This talk will provide a summary of the experiment, along with a report on the current status.
The MAgnetized Disc And Mirror Axion eXperiment is designed to search for dark matter axions in the mass range of 40 to 400 µeV, a range previously inaccessible by other experiments. This mass range is favored by models in which the PQ symmetry is broken after inflation. The required sensitivity is reached in MADMAX by applying the dielectric haloscope approach, exploiting the axion to photon conversion at dielectric surfaces within a strong magnetic field. For MADMAX a system of 80 movable dielectric discs of 1.25 m diameter, the so-called booster, inside an approximately 9 T magnetic field is foreseen. The experiment will be located at DESY Hamburg in Germany and is currently entering its prototyping phase.
One of the important steps on the path towards the MADMAX prototype is of course the understanding and calibration of the booster and its behavior which is currently pursued using small scale closed systems. Vast progress has been made here culminating in an Axion-Like-Particle search with this closed system utilizing the MORPURGO magnet at CERN, which will also host the MADMAX prototype in the future. Along with these activities the development of the prototype booster and its components is advancing, including various tests of piezo-electric actuators foreseen for the manipulation of the dielectric disks at cryogenic temperatures and high magnetic fields in CERN as well as DESY facilities.
In this contribution, results from the small scale closed booster system, including the ALP search at CERN, will be shown along with the results of extensive simulation studies looking at various aspects of the prototype and full-scale booster. Also, the advanced design of the prototype booster including results form the tests of the newly developed piezo based drive system at cryogenic temperatures and high magnetic fields will be presented. Together with all these results guiding the path towards the MADMAX (prototype) experiment an outlook will be given on the time schedule for the MADMAX prototype including the operation and the planned ALP search at CERN as well as on ongoing developments such as future low noise receivers.
DMRadio is a series of experiments that searches for axions using the axion-photon coupling at frequencies lower than those which have been achieved with conventional cavity haloscopes. In this talk we present the status of two experiments of the DMRadio program: DMRadio 50L and DMRadio m$^3$. DMRadio 50L uses a toroidal magnet and a high-Q LC-oscillator with target sensitivity to axions with $g_{a\gamma\gamma} < 5\times 10^{-15} \text{GeV}^{-1}$ between 5 kHz and 5 MHz (20 peV to 20 neV). DMRadio m$^3$ consists of a higher frequency LC-oscillator in a solenoidal magnet with target sensitivity to QCD axions between 5 MHz and 200 MHz (20 neV to 0.8 $\mu$eV).
We revisit and improve on previous calculations of the Migdal effect, the excitation and ionisation of atoms after a neutral particle scatters off the nucleus. We present results for the noble elements, and also carbon and fluorine. Our improved calculations are particularly import for neutron scattering experiments, which aim to test the Migdal effect in the laboratory. In this case, deviations from the dipole approximation and secondary ionisation processes have a significant effect on the size of the Migdal effect.
The atomic Migdal effect is increasingly invoked to extend the sensitivity of direct dark matter searches to light WIMPs, in a regime where nuclear recoils produce no detectable signature but the accompanying Migdal electron emission is in principle detectable. Despite this, this elusive effect has never been measured in nuclear scattering. The Migdal In Galactic Dark mAtter expLoration (MIGDAL) experiment aims to make an observation of this process induced by fast-neutron scattering in a low-pressure gas, probing a range of nuclear recoil energies and target elements. MIGDAL will use an Optical Time Projection Chamber filled with low-pressure CF4, initially pure and later on mixed with other gases, to record high-resolution track images and timing information from scintillation and ionisation readout that will be combined to reconstruct tracks in 3D. This talk will describe the design of the experiment and present preliminary commissioning data, ahead of the first campaign of measurements with intense D-D and D-T neutron generators at the NILE facility at the Rutherford Appleton Laboratory (UK).
I present qBounce using the novel high precision method of Gravity Resonance Spectroscopy (GRS) using Ramseys method of separated oscillating fields.
It utilises ultracold neutrons bound to the surface of a mirror by gravity. Because of the zero charge and low polarizability of the neutron, this system is insensitive to many external influences. In 2018, the first proof of principle of GRS was published. Since then, improvements to the experimental setup were investigated and implemented to allow for higher precision and stability of the system. During 2020 and 2021,
the spectrometer showed its full potential, and precision measurements of the transition frequency between bound states were taken.
In my contribution, I will present the technique and possibilities to apply this method for dark matter and dark energy searches.
The ANDROMeDa (Aligned Nanotube Detector for Research On MeV Darkmatter) project aims to develop a novel Dark Matter (DM) detector based on carbon nanotubes: the Dark-PMT. The detector is designed to be sensitive to DM particles with mass between 1 MeV and 1 GeV. The detection scheme is based on DM-electron scattering inside a target made of vertically-aligned carbon nanotubes. Carbon nanotubes are made of wrapped sheets of graphene, which is a 2-dimensional meterial: therefore, if enough energy is transferred to overcome the carbon work function, the electrons are emitted directly in the infra-tube vacuum. Vertically-aligned carbon nanotubes have reduced density in the direction of the tube axes, therefore the scattered electrons are expected to leave the target without being reabsorbed only if their momentum has a small enough angle with that direction, which is what happens when the tubes are parallel to the DM wind. This grants directional sensitivity to the detector, a unique feature in this DM mass range. We will report on the construction of the first Dark-PMT prototype, on the establishment of a state-of-the-art carbon nanotube growing facility in Rome, and on the characterizations of the nanotubes with XPS and angular-resolved UPS spectroscopy performed in Sapienza University, Roma Tre University, and at synchrotron facilities. ANDROMeDa was recently awarded a 1M€ PRIN2020 grant with which we aim, over the course of the next three years, to construct the first large-area cathode Dark-PMT prototype with a target of 10 mg of carbon. The main focus of the R&D will be the development of a superior nanotube synthesis capable of producing optimal nanotubes for their use as DM target. In particular, the nanotubes will have to exhibit high degree of parallelism at the nanoscale, in order to minimize electron re-absorption.
We introduce a new dark-matter detection experiment that will enable the search of keV-range super-light dark matter, representing an improvement of the minimum detectable mass by more than three orders of magnitude over the ongoing experiments. This is possible by integrating intimately the target material, π-bond electrons in graphene, into a Josephson junction to achieve a high sensitivity detector that can resolve a small energy exchange from dark matter as low as ~0.1 meV. We investigate detection prospects with pg-, ng-, and 𝜇g-scale detectors by calculating the scattering rate between dark matter and the free electrons confined in two-dimensional graphene with Pauli blocking factors included. We find not only that the proposed detector can serve as a complementary probe of super-light dark matter but also achieve higher experimental sensitivities than other proposed experiments, i.e. in having a low detectable threshold provided the same target mass, thanks to the extremely low energy threshold of our graphene-based Josephson junction sensor.
As the age of WIMP-scale dark matter (DM) draws to a close thanks to the ever-increasing sensitivity of direct detection experiments, the majority of DM parameter space outside of the weak scale remains to be explored. Sub-GeV DM can excite electronic transitions in a variety of molecular and nano-scale systems which have sub-eV scale thresholds. Quantum dots are nanocrystals of semiconducting material whose band-edge electronic properties are determined by their characteristic size. I will discuss the importance of molecular and mesoscopic systems as new directions in the direct detection of dark matter focusing on the use of quantum dots as detector targets. I will show that QDs present a particularly interesting target with inherently low-background signals and low-cost scalability.
Dark matter (DM) detectors employing a Spherical Proportional Counter (SPC) have demonstrated a single-electron detection threshold and are projected to have small background rates. We explore the sensitivity to DM-electron scattering with SPC detectors in the context of DarkSphere, a proposal for a 300 cm diameter fully-electroformed SPC. SPCs can run with different gases, so we investigate the sensitivity for five targets: helium, neon, xenon, methane, and isobutane. We use tools from quantum chemistry to model the atomic and molecular systems, and calculate the expected DM induced event rates. We find that DarkSphere has the potential to improve current exclusion limits on DM masses above 4 MeV by up to five orders of magnitude. Neon is the best all-round gas target but using gas mixtures, where methane and isobutane constitute 10% of the gas, can improve the sensitivity, especially when combined with helium. Our study highlights the currently untapped potential of SPCs to search for DM-electron scattering in the MeV-to-GeV DM mass range.
Despite its remarkable success, the standard LCDM paradigm has been challenged lately by significant tensions between different datasets. This has reinvigorated interest in beyond-LCDM models, such as dark matter models with interactions or non-negligible velocities, known collectively as non-cold dark matter. These models result in a suppression of the matter power spectrum on small scales, making them an ideal target to be constrained with Lyman-alpha data. In this talk I will discuss a method to use Lyman-alpha data that does not need the usual computationally-expensive hydrodynamical simulations. I will present recent competitive bounds for warm dark matter, mixed warm+cold models, and dark matter interactions, highlighting the broad range of applicability of this new method.
Stellar streams are very old, dynamical objects consisting of a collection of stars that originate from tidal disruptions of a globular cluster. In a galaxy like the Milky Way, these systems have the potential to be an extremely sensitive probe of dark matter substructure, baryonic physics, and the evolution history of the stream. In principle, this can be achieved by combining high precision observations at facilities such as Gaia, and consistent modelling of these stellar orbits - which typically trace out a large portion of the galactic gravitational potential.
On the other hand, making statistically robust statements about quantities of interest - e.g. the dark matter subhalo mass function - is extremely challenging. To do so requires some sort of marginalisation over the dynamical history and initial conditions of the stream, its stochastic interactions with dark matter substructures, as well as a reasonable model for foreground effects in the observations. Purely as a result of the huge number of free parameters this introduces, classical statistical methods scale very poorly and must rely instead on constructing bespoke summary statistics or ignoring a subset of effects in the modelling.
In this talk, I will present preliminary results for the GD-1 stellar stream using a powerful new approach within the framework of simulation-based inference: truncated marginal neural ratio estimation (TMNRE). This approach is based on the targeted training of high-precision neural networks for parameter inference, and scales to highly complex models. After introducing the methodology, we will show how this can be applied concretely to real Gaia data for GD-1 to obtain limits on fundamental properties of dark matter and the formation of substructure in galactic halos.
The properties of dark matter halos and subhalos on sub-galactic scales, below 10^9 solar masses, depend on the formation mechanism, mass, and possible interactions of the dark matter particle, as well as the initial conditions for structure formation determined by the primordial matter power spectrum and inflation. As such, inferences of the abundance and density profiles of low-mass halos can be recast as constraints on fundamental physics. Strong gravitational lensing by galaxies provides a direct, purely gravitational means of inferring the properties of dark matter structure down to roughly 10^7 solar masses with existing data. I will describe recent work that uses measurements of image magnifications in quads to infer properties of dark substructure in strong lens systems. I will then discuss what these inferences can tell us about the nature of dark matter, including potential self-interactions, the free-streaming length, and connections to the primordial matter power spectrum.
In this work, we carry out a suite of specially-designed numerical simulations to shed further light on dark matter (DM) subhalo survival at mass scales relevant for gamma-ray DM searches, a topic subject to intense debate nowadays. Specifically, we have developed and employed an improved version of DASH, a GPU $N$-body code, to study the evolution of low-mass subhaloes inside a Milky Way-like halo with unprecedented accuracy. We have simulated subhaloes with varying mass, concentration, and orbital properties, and considered the effect of the gravitational potential of the Milky-Way galaxy itself. In addition to shedding light on the survival of low-mass galactic subhaloes, our results will provide detailed predictions that will aid current and future quests for the nature of DM.
Uncovering the nature of dark matter (DM) is one of the most pressing pursuits in modern physics and cosmology. Astronomical observations are the key to understand the nature of DM and have been revealing the possibility that DM particles interact non-gravitationally with each other. It began with observations of the collision of nearby galaxy clusters. More recently, measurements of large DM densities at the center of the Milky Way’s galaxy satellites are indicating that DM-DM interactions can potentially induce gravothermal core collapse, an effect where frequent DM-DM interactions heat the central DM halo core, causing it to rapidly contract and raise in density. Is dark matter self-interacting? Can observations from cluster-size galaxies combined with measurements of local satellite galaxies dynamics be used to prove/or alternatively rule out this scenario? In this talk I will answer these questions and review the latest constraints of self-interacting dark matter (SIDM) on small and large scales. I will also introduce the TangoSIDM project, a simulation suite project that models cosmological hydrodynamical simulations of structure formation in a SIDM universe. I will show how the TangoSIDM simulations are used to derive robust constraints of the DM scatter cross section on dwarf galaxy scales. Finally, I will discuss the next steps for the astronomical-particle physics connection.
Precision analysis of galaxy-galaxy strong gravitational lensing images provides a unique way of characterizing dark matter (DM) low-mass halos and could allow us to uncover the fundamental properties of DM's constituents. In recent years, gravitational imaging techniques made it possible to detect a few heavy subhalos. However, gravitational lenses contain numerous subhalos and line-of-sight halos, whose subtle imprint is extremely difficult to detect individually. Existing methods for marginalizing over this large population of sub-threshold perturbers in order to infer population-level parameters are typically computationally expensive, or require compressing observations into hand-crafted summary statistics, such as a power spectrum of residuals.
We will present the first analysis pipeline to combine parametric lensing models with a recently-developed targeted simulation-based inference technique called truncated marginal neural ratio estimation (TMNRE), in order to constrain the WDM halo mass function cutoff scale directly from multiple lensing images. In a proof-of-concept application to simulated data with Hubble Space Telescope (HST) resolution, we will show that our approach enables empirically testable inference of the DM cutoff mass down to $10^7\ M_\odot$, through marginalization over a large population of realistic perturbers that would be undetectable on their own, and over lens and source parameters uncertainties. Our results demonstrate that TMNRE is in principle able to extract the wealth of information regarding DM's nature contained in existing lensing data and in the large sample of lenses that will be delivered by near-future telescopes. We will conclude showing preliminary results on real HST data.
Due to the coherent behavior of ultra-light dark matter (ULDM), in the central region of the dark matter halos, solitonic cores can form and change the small-scales predictions of the $\Lambda$CDM model. Analogously to the condensed matter systems, a rotating condensate halo can form defects with important observational consequences. These defects were observed numerically; however, a theoretical description that reproduces all the simulation features is lacking. In this talk, I discuss a classification of the vortices and their dynamics in superfluid/Bose-Einstein condensate halos. We identify topological defects in the supefluid condensate using standard Quantum Field Theory tools and consider the existence of BEC vortices formed outside the condensate by destructive interference patterns. We rely on solving the Gross-Pitaevskii-Poisson system for a self-interacting ULDM, and present simulations in a controlled environment to show the general structure of the vortices system.
XENONnT was successfully commissioned in 2021 and has started science data taking. In addition to the new TPC, the experiment was augmented by a new water Cherenkov neutron-veto surrounding the central detector. In this talk, we present the first results of XENONnT’s nuclear recoil (NR) response calibration as well as the calibration of the neutron-veto detection efficiency. This NR calibration, to our knowledge for the first time in a large liquid xenon TPC, employs tight coincidence tagging of nuclear recoils, utilizing the 4.4 MeV gamma-ray from an Americium-Beryllium source in coincidence with the emitted neutron. We show that this results in an effectively background-free NR calibration at a reduced S1 threshold by removing accidental coincidences and other backgrounds. The reverse event topology – 4.4 MeV gamma in the TPC and neutron in the veto detector – is used to measure the neutron veto detection efficiency.
The growing interest in the interactions between dark matter particles and electrons has received a further boost by the observation of an excess in electron recoil events in the XENON1T experiment. Of particular interest are dark matter models in which the scattering process is inelastic, such that the ground state can upscatter into an excited state. The subsequent exothermic downscattering of such excited states on electrons can lead to observable signals in direct detection experiments and gives a good fit to the XENON1T excess. In this talk, I will discuss terrestrial upscattering, i.e. inelastic scattering of dark matter particles on nuclei in the Earth, as a plausible origin of such excited states. I will demonstrate that both analytical and Monte Carlo methods allow for a detailed prediction of the excited density and velocity distribution. These results show a time dependence of the flux of excited states resulting from the rotation of the Earth. This daily modulation offers an intriguing opportunity to distinguish this mechanism from alternative explanations of the XENON1T excess and to additionally determine the DM mass.
This talk will be based on https://arxiv.org/abs/2112.06930.
LUX-ZEPLIN (LZ) is a dark matter direct detection experiment located at the Sanford Underground Research Facility in Lead, South Dakota. The experiment consists of a dual-phase xenon Time Projection Chamber with an active volume of 7 tonnes (5.6 tonne fiducial), shielded by an active liquid xenon skin region, an active gadolinium-loaded liquid scintillator veto, and an ultrapure water veto. LZ is projected to achieve a sensitivity of 1.4 x 10^-48 cm^2 for the spin-independent WIMP-nucleon cross section at 40 GeV/c^2 in 1000 live days. This talk will provide an overview of the LZ experiment and report on its status.
Darkside-20k will exploit the physical and chemical properties of liquid argon housed within a large dual-phase time project chamber (TPC) in its direct search for dark matter. The TPC will utilize a compact, integrated design with many novel features to enable the 20t fiducial volume of underground argon. Underground argon (UAr) is sourced from underground CO2 wells and depleted in the radioactive isotope 39-Ar, greatly enhancing the experimental sensitivity to dark matter interactions. Sourcing and transporting O(100 t) of UAr for DarkSide-20k is costly, and a dedicated single-closed-loop cryogenic system has been designed, constructed, and tested to handle the valuable UAr. We present an overview of the DarkSide-20k TPC design and the first results from the UAr cryogenic system.
DarkSide-50 is a direct WIMP dark matter detection experiment at Laboratori Nazionali del Gran Sasso (LNGS) that used argon as the target material. Exploiting the ionization signal from a dual-phase time projection chamber (TPC) filled with low radioactivity argon from an underground source, it has set the strongest limit against WIMP with a mass in the GeV/c2 region. A new analysis has recently been carried out with a larger exposure coupled with an improved understanding of the detector response. In this talk, I will give the details of the updated search for the low mass WIMP using only ionization signal.
DEAP-3600 is a WIMP dark matter direct-detection experiment located 2 km underground at SNOLAB (Canada), which uses liquid argon as the target material. The detector consists of 3.3 tonnes of liquid argon in a large acrylic cryostat instrumented with 255 photomultiplier tubes.
In this talk, we first analyze our data exploring different non-relativistic effective operators for the Dark matter-nucleon interaction, evidencing the importance of multiple target materials to characterize it. In particular, this research includes some isospin-violating scenarios where world-leading limits were achieved with DEAP. We will also discuss the consequences of using models different than the standard halo model, like halo substructures, for the dark matter distribution in the galaxy. We will close presenting the physics program beyond WIMP searches, the hardware upgrades being implemented and the prospects of this experiment once they are finalized.
The proposed LUXE experiment (LASER Und XFEL Experiment) at DESY, Hamburg, using the electron beam from the European XFEL, aims to probe QED in the non-perturbative regime created in collisions between high-intensity laser pulses and high-energy electron or photon beams. This setup also provides a unique opportunity to probe physics beyond the standard model. In this talk we show that by leveraging the large photon flux generated at LUXE, one can probe axion-like-particles (ALPs) up to a mass of 350 MeV and with photon coupling of 3x10^{-6} GeV^{-1}. This reach is comparable to the background-free projection from NA62. In addition, we will discuss other probes of new physics such as ALPs-electron coupling.
Axion-like particles (ALPs), the QCD axion, are well motivated candidates for Cold Dark Matter. Such models may be divided into two classes depending on whether the associated U(1) symmetry is broken or not during inflation. The latter case is usually considered to be quite simple with relic density depending only on the corresponding decay constant and with no constraints from the known bounds on isocurvature perturbations. We will show that the situation is much more complicated. We find that many such models predict unacceptable isocurvature perturbations. Moreover, the relic density may strongly depend on the details of a considered model (quite often in a more complicated way than in the case of models with U(1) symmetry broken during inflation). We will discuss conditions which should be fulfilled by ALP models with U(1) unbroken during inflation to be phenomenologically interesting.
In 2021 the Quantum Sensors for the Hidden Sector (QSHS) collaboration in
the UK was founded and received funding to develop and demonstrate quantum
devices with the potential to detect hidden sector particles in the
microeV to 100microeV mass window. The collaboration has been developing a
range of devices and has started to develop a high-field, low-temperature
facility at Sheffield University to characterise and test the devices in a
haloscope geometry. Here, I introduce the QSHS collaboration aims and
current progress.
The axion provides a solution for the strong CP problem and is one of the promising candidates for dark matter. In 2020, the XENON1T experiment reported an excess of electronic recoil events, possibly interpreting as the solar axion, an enhanced neutrino magnetic moment or the beta decays of tritium. The Investigating Solar Axion by Iron-57 (ISAI) is being developed as a complemented table-top experiment for an independent confirmation of the solar axion scenario. Probing an X-ray emission from the nuclear transitions associated with the axion-nucleon coupling is the leading approach. Therefore, our plan is to search for the monochromatic 14.4 keV X-ray from the first excited state of Iron-57 using a modern noble pixel detector, dubbed XRPIX, under an extremely low-background environment. We highlight scientific objectives, experimental design and latest status.
A search for resonance excitation of $^{7}$Li by the solar axion has been studied with the Li$_{2}$MoO$_{4}$ crystals in the AMoRE experiment. The axion is a hypothetical particle proposed to solve the so-called strong CP problem of quantum chromodynamics (QCD). If the axions exist, they could be extensively produced inside the Sun, then can be detected in the inverse reaction of resonance absorption by detecting nuclei. The Li$_{2}$MoO$_{4}$ crystals used as a target and detector for the AMoRE experiment give this mechanism 12% of detection efficiency. The data from 1.6 kg Li$_{2}$MoO$_{4}$ (118.5 g of $^{7}$Li contained) crystals were accumulated using phonon sensors at a few tens mK temperatures for 6.5 months at the Yangyang underground laboratory in South Korea. The detailed analysis procedure and the preliminary results will be presented. Also, the potential backgrounds will be discussed.
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The DAMA/LIBRA–phase2 experiment deep underground at Gran Sasso is presented. The improved experimental configuration with respect to the phase1 allowed a lower software energy threshold. The DAMA/LIBRA–phase2 data confirm the evidence of a signal that meets all the requirements of the model independent Dark Matter annual modulation signature, at high C.L. Recently additional data have been released. The model independent DM annual modulation result is compatible with a wide set of DM candidates. A new configuration of DAMA/LIBRA–phase2 is now running with a further lowered energy threshold. The perspectives will be outlined.
In this talk I want to overview the (unorthodox) scenario when the baryogenesis is replaced by a charge segregation process in which the global baryon number of the Universe remains zero. In this, the so-called axion quark nugget (AQN) dark matter model the unobserved antibaryons come to comprise the dark matter in the form of dense nuggets. I specifically discuss the applications to the
the DAMA/LIBRA experiment which shows 12 sigma evidence for an annual modulation in the (1-6)~ keV energy range, strongly suggesting that the observed modulation has the dark matter origin. However, the conventional interpretation in terms of WIMP-nucleon interaction is excluded by other experiments. This proposal can be directly tested by COSINE-100, ANAIS-112, CYGNO and other similar experiments. I will also mention other possible manifestations of the same model such as the observed mysterious diffuse UV radiation in the galaxy, which can be also explained within the same framework with the same set of parameters.
The talk is based on several recent papers including:
A. Zhitnitsky,
``DAMA/LIBRA annual modulation and Axion Quark Nugget Dark Matter Model,''
Phys. Rev. D 101, 083020 (2020) [arXiv:1909.05320 [hep-ph]]
A. Zhitnitsky,
``The mysterious diffuse UV radiation and axion quark nugget dark matter model''
Phys. Lett. B 828, 137015 (2022) [arXiv:2110.05489 [hep-ph]]
A. Zhitnitsky, brief invited review:
"Axion quark nuggets. Dark matter and matter -antimatter asymmetry: Theory, observations and future experiments"
Mod. Phys. Lett. A, 36, 2130017 (2021) [arXiv:2105.08719 [hep-ph]]
DAMA/LIBRA observation of an annual modulation in the detection rate compatible with that expected for dark matter particles from the galactic halo has accumulated evidence for more than twenty years. It is the only hint about a positive identification of the dark matter, but it is in strong tension with the negative results of other very sensitive experiments. However, this comparison is model-dependent. By using the same target material than DAMA/LIBRA experiment, NaI(Tl), such a comparison is (almost) independent in dark matter particle and halo models. ANAIS-112 experiment, using 112.5 kg of NaI(Tl) as target, is taking data at the Canfranc Underground Laboratory in Spain since August 2017. Results corresponding to three-year are compatible with the absence of modulation and in tension with DAMA/LIBRA result. In August 2022, five years of data taking will be completed. Present status of the experiment and prospects to test DAMA/LIBRA beyond three sigma will be reported in this talk together with recent analysis improvements and a discussion on open data strategy and systematics in the comparison of both experiments.
Dark matter is a main ingredient of the cosmos, its nature, despite of enormous progress in terrestrial direct dark matter searches, is still undiscovered. The DAMA/LIBRA claim creates since more than 25 years a controversial situation in the field of direct dark matter detection. Most prominently, results from phase 2 add new constraints since they imply that any interpretation of DAMA in terms of dark matter requires non-standard interactions of dark matter particles, or non-standard astrophysical assumptions, or both.
For a fully model-independent investigation of the nature of the DAMA/LIBRA signal, experiments which use the same material as DAMA/LIBRA are mandatory.
COSINUS will use crystals of NaI, however not operating them as mere scintillation detectors, but as so-called cryogenic scintillating calorimeters cooled to milli-Kelvin temperatures. COSINUS detectors provide a simultaneous and independent measurement of both the temperature signal and the scintillation light signal caused by a particle interaction. Since the amount of produced light depends on the particle type (light quenching), this detection technique yields identification of the type of interacting particle on an event-by-event basis.
In this talk we will show new results from the latest generation of COSINUS prototype detectors utilizing the so-called "remoTES“ detector readout principle. Furthermore we will present on the current status of the experimental setup installation presently ongoing at the Gran Sasso underground lab in Italy.
NaI(Tl) based scintillation detectors have become a staple in the field of direct dark matter searches, with the DAMA-LIBRA experiment being the standout for its reported observation which is in direct contrast with other results. In order to accurately calibrate the energies of WIMP-induced nuclear recoil signals and conclusively rule out the parameter space covered by DAMA/LIBRA, precise measurements of the quenching factor of the NaI crystals is essential for each of these experiments, as it is well established that electron recoils and nuclear recoils have dissimilar scintillation light yields.
In this study, we present first preliminary results of a systematic analysis that has been carried out by the COSINUS collaboration to measure the quenching factor values primarily in the low recoil energies of 1-30$keV_{nr}$ , in order to better understand the discrepancies/uncertainties reported by various experiments. Five ultra-pure NaI crystals, manufactured by the Shanghai Institute for Ceramics, each of which have varying Tl dopant concentrations, were irradiated with a mono-energetic neutron beam at the Triangle Universities National Laboratory, North Carolina, USA to study its impact on the quenching factor values in our desired recoil energy range.
For nearly two decades the DAMA Collaboration has been observing a modulating signal compatible with that expected from a dark matter presence in our galaxy. However, interpretations of this with the standard assumptions for dark matter particles are strongly ruled out by a large number of other experiments. This tension can be relaxed somewhat by making more tailored choices for the dark matter model and properties of interest, but expanding the models of interest in such a way makes it impossible to test the DAMA modulation conclusively. In order to understand the exact nature of this signal, we need to use a detector based on the same target (NaI(Tl)), which would be sensitive to exactly the same particle interaction models as DAMA.
There are a number of such experiments in the data taking or commissioning stages designed to do just this, two of which (ANAIS and COSINE) recently released their results after 3 years of data taking. Interestingly, the modulation observed by the two experiments deviate from each other by 2$\sigma$, while being within 3$\sigma$ of the DAMA result. This talk explores the necessity of these model independent tests through a discussion of different particle interaction models and dark matter velocity distributions. I will also address potential differences between NaI(Tl) based detectors that could lead to the differing results to date, with a particular focus on the quenching factor.
The SABRE (Sodium-iodide with Active Background REjection) South experiment is a direct dark matter search detector, made of radio-pure NaI(Tl) crystals surrounded by a liquid scintillator veto. The achievement of ultra-low background rate is essential to provide a model independent test of the signal observed by the DAMA/LIBRA experiment whose claim has not been verified yet.
The SABRE South experiment will be located at the Stawell Underground Physics Laboratory (SUPL), Australia. SUPL is the first deep underground (1024 m) laboratory in the Southern Hemisphere, which is scheduled to be operational by mid-2022. The laboratory will not only house rare event physics searches, such as SABRE, but also measurement facilities to support low background physics experiments and applications like radiobiology and quantum computing.
The SABRE South detector assembly is planned to start once SUPL is finalised, and its commissioning is expected to occur in 2023.
The SABRE South NaI(Tl) crystal arrays will be immersed in a linear alkyl benzene (LAB) scintillator which acts as a veto by detecting signals through eighteen 8” R6912 Hamamatsu PMTs. Careful calibration studies must be set up in order to assess the PMT responses and the scintillator properties.
This talk will describe the SABRE South’s location at SUPL, its final detector layout and its current status, and the calibration system design which will be implemented to test the veto PMTs.
The SABRE project aims to produce ultra-low background NaI(Tl) scintillating detectors to carry out a model-independent search for dark matter through the annual modulation signature, with an unprecedented sensitivity to confirm or refute the DAMA/LIBRA claim. The ultimate goal of SABRE is to operate two independent NaI(Tl) crystal arrays located in the northern (SABRE North) and southern (SABRE South) hemispheres to identify possible contributions to the modulation from seasonal or site-related effects.
As a large fraction of the background in the 1-6 keV energy region-of-interest (ROI) for dark matter search come from radioactive contaminants in the crystal themselves, SABRE North has carried out an extensive R&D on the production of ultra radio-pure NaI(Tl) crystals. Direct counting of beta and gamma particles with the SABRE Proof-of-Principle detector, equipped with a liquid scintillator active veto and operated at the Gran Sasso National Laboratory (LNGS) has already demonstrated an average background rate of 1.20 $\pm$ 0.05 counts/day/kg/keV for the so-called NaI-33 crystal, which is a breakthrough since the DAMA/LIBRA experiment. In particular, the amount of potassium contamination is found to be lower than 4.7 ppb at 90% CL, lowest ever achieved for NaI(Tl) crystals.
Data acquired for about one year with the NaI-33 detector into a purely passive shielding have shown that, if the crystal vetoable internal contaminations are as low as in the NaI-33, the active veto is no longer a crucial feature to achieve the required sensitivity. Indeed, our background model indicates that the rate is dominated by $^{210}$Pb decays and that a large fraction of this contamination is located in the PTFE reflector wrapping the crystal. Beside the replacement of this material, ongoing developments of the crystal manufacture are aimed at a further reduction of the intrinsic background. The present results represent a benchmark for the development of next-generation NaI(Tl) detectors for the direct detection of dark matter particles, with a projected background rate lower than $\sim$0.3 counts/day/kg/keV. With this level of background an array of NaI(Tl) scintillating crystals with a total mass of just a fraction of the present generation experiments can achieve the ultimate verification of the DAMA result in about three years.
We examine the degree of spatial coherence of the field configuration in fuzzy dark matter halos. The compact soliton sitting at the centre of a halo is completely coherent and is surrounded by an incoherent field whose density follows the Navarro-Frenk-White profile and exhibits turbulent features. This spatial transition from coherence to incoherence can be well characterized by two parameters according to a generalized empirical core-halo profile, whose oscillations are found to be anti-correlated to the oscillation of the peak value of the power spectrum of the halo; their oscillation frequencies scale with the soliton core density. In contrast, the outer halo reaches a quasi-steady state with an approximately constant characteristic granule size correlated with the intervortex spacing.
We acknowledge funding from European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 897324 (upgradeFDM).
The nature of dark matter, one of the major components of the cosmic standard model, remains one of the outstanding problems in physics. One interesting model is scalar field dark matter (SFDM), which fits naturally into observations in both particle physics and cosmology. Simulations and calculations using SFDM often use a classical field approximation (MFT) of the underlying quantum field theory. And while it is suspected that large occupation numbers make this description good in the early universe, it is possible that this approximation fails during nonlinear structure growth and begins to admit important quantum corrections. To investigate this possibility, we compare simulations using the MFT to those that take into account these corrections. By studying their behavior as we scale the total number of particles in the system we can estimate how long the MFT remains an accurate description of the system. We estimate this time scale for a typical halo may be of order ~1 Gyr, short compared to the age of the universe. In this talk we will explain how these simulations are performed, as well as their results, and their potential implications.
Fuzzy Dark Matter (FDM) models admit self-similar solutions which are very different from their Cold Dark Matter (CDM) counterparts and do not converge to the latter in the semiclassical limit. In contrast with the familiar CDM hierarchical collapse, they correspond to an inverse-hierarchy blow-up. Constant-mass shells start in the nonlinear regime, at early times, with small radii and high densities, and expand to reach at late times the Hubble flow, up to small linear perturbations. Thus, larger masses become linear first. This blow-up approximately follows the Hubble expansion, so that the central density contrast remains constant with time, although the width of the self-similar profile shrinks in comoving coordinates. As in a gravitational cooling process, matter is ejected from the central peaks through successive clumps. As in wave systems, the velocities of the geometrical structures and of the matter do not coincide, and matter slowly moves from one clump to the next, with intermittent velocity bursts at the transitions. These features are best observed using the density-velocity representation of the nonrelativistic scalar field, or the mass-shell trajectories, than with the Husimi phase-space distribution, where an analogue of the Heisenberg uncertainty principle blurs the resolution in the position or velocity direction. These behaviours are due to the quantum pressure and the wavelike properties of the Schrödinger equation. Although the latter has been used as an alternative to N-body simulations for CDM, these self-similar solutions show that the semiclassical limit needs to be handled with care.
In this talk, I will present a Neural Network-improved version of DarkHistory, a code package that self-consistently computes the early universe temperature, ionization levels, and photon spectral distortion due to exotic energy injections. We use simple multilayer perceptron networks to store and interpolate complicated photon and electron transfer functions, previously stored as large tables. This improvement allows DarkHistory to run on small computers without heavy memory and storage usage while preserving the physical predictions to high accuracy. It also enables us to explore adding more parametric dependence in the future to include additional physical processes and spatial resolution.
Compact stellar objects are promising cosmic laboratories to test fundamental interactions, in particular they could shed light on the nature of dark matter (DM). DM captured by the strong gravitational field of these stellar remnants transfers kinetic energy to the star during the collision. This together with further DM annihilation in the stellar interior can have various observational consequences such as the anomalous heating of old compact stars. A key ingredient to derive bounds on DM interactions in any scenario involving the accumulation of DM in a star is the proper calculation of the capture rate. We improve former calculations of the capture rate in both white dwarfs (WDs) and neutron stars (NSs), which rely on approximations or simplifying assumptions. We model the stellar interior and related microphysics by assuming an equation of state and solving the Tolman-Oppenheimer-Volkoff equations. Aside from the stellar structure, we account for gravitational focusing, a fully relativistic scattering treatment when relevant, the star opacity, multiple scattering effects, Pauli blocking when light DM scatters off degenerate targets, realistic form factors, and strong interactions in the case of baryonic NS target species. For WDs, we consider DM scattering off the non-degenerate ions and the degenerate electrons. Using an effective field theory approach, we show that if there is DM in the innermost region of the globular cluster Messier 4, which contains old WDs, these WDs can probe the elusive sub-GeV mass range for both DM-nucleon and DM-electron scattering. In NSs, DM can be captured via collisions with strongly degenerate nucleons, relativistic leptons, and hyperonic matter which may exist in the ultra-dense core of heavy NSs. We project the potential NS sensitivity to DM-lepton and DM-nucleon scattering which greatly exceeds that of direct detection experiments.
Thermal dark matter scenarios are characterized by an exponential decrease in the comoving dark matter number density as the temperature drops below the dark matter mass in the early Universe. In this talk, we will discuss a novel thermal framework, bouncing dark matter, where the abundance instead undergoes a ``bounce:" a transition from the exponential fall to an exponential rise, resulting in an enhancement of the final abundance by several orders of magnitude. We will discuss the general idea, multiple realizations, and phenomenological aspects of this mechanism.
Unusual masses of black holes being discovered by gravitational wave experiments pose fundamental questions about their origin. More interestingly, black holes with masses smaller than the Chandrasekhar limit (1.4 solar mass) are essentially impossible to produce through any standard stellar evolution. Primordial black holes, with fine-tuned parameters, and with no compelling formation mechanisms, are the most discussed explanation of these objects. In this talk, I will discuss a simple production channel of these low mass black holes. Particle dark matter with no antiparticle counterpart, owing to their interaction with stellar nuclei, can catastrophically accumulate inside compact stars, and eventually transmute them to sub-Chandrasekhar mass black holes, ordinarily forbidden by the Chandrasekhar limit. I will point out several avenues to test the origin of these low mass black holes, concentrating on the cosmic evolution of the binary merger rates. I will demonstrate how measurement of these merger rates, especially at higher redshifts, by the imminent gravitational wave detectors can conclusively determine the origin of these low mass black holes, and therefore, can test the particle dark matter hypothesis.
In many rare event searches noble gases are used as detector target. In order to achieve high sensitivities, the target material needs to be continuously circulated and cleaned from impurities and radioactive contaminants. To pump and compress xenon gas through such systems an ultra-clean, hermetically sealed, radon-free pump without oil lubrication is indispensable. Taking into account the increasing target masses of these low background experiments, higher purification fluxes are necessary and multiple parallel pumps may be required. For such purposes and especially for a radon removal system for XENONnT, a four cylinder magnetically-coupled pump was developed to ensure high cleanliness and stable operation.
This poster will show the basic idea of the piston pump and give an overview of the archived high-performance.
This research was partially supported by BMBF under contract 05A20PM1.
LUX-ZEPLIN (LZ) is a dark matter direct detection experiment consisting of a dual-phase xenon time projection chamber with an active mass of 7 tonnes, which is surrounded by a xenon skin region and liquid scintillator to serve as active vetoes for gamma-ray and neutron backgrounds, respectively. With an extensive material assay effort, xenon purification campaign, and detector assembly under rigorous cleanliness protocols, LZ has attained an ultra-low background environment that enables a predicted spin-independent WIMP-nucleon cross section of 1.4x10^-48 cm^2 at a WIMP mass of 40 GeV/c^2 after a livetime of 1000 days. To achieve this unprecedented sensitivity, it is essential to produce a well-constrained background model. This poster will highlight the procedure of background model fitting with in situ measurements, along with implications for simulations tuning and the required radioassay measurement precision for the next generation of dark matter experiments.
COSINUS is devoted to the study of the nature of the signal detected by the DAMA/LIBRA experiment and aims to definitely establish if the observed annually modulated signal is or is not a dark matter signature. The benefit of the technique employed by COSINUS, which develops cryogenic scintillating calorimeters with NaI-absorbers equipped with TES thermometers, consists in the event-by-event discrimination of electron/gamma events and nuclear recoils. The recent results, obtained with the new NaI-remoTES prototype, show the potentialities of this technique. In this contribution, we present updated COSINUS projections for the dark matter search in different scenarios, compared to the latest results of DAMA/LIBRA, and we explain the additional contribution of COSINUS to the cross-check campaign of DAMA/LIBRA with respect to NaI-based scintillators at room-temperature.
For over twenty-five years the DAMA/LIBRA (formerly DAMA/NaI) experiment has observed an annual modulation signal that is consistent with a dark matter explanation. This signal is, currently, in tension with the null results observed by other searches that utilize different target detectors. The COSINUS experiment will perform a model-independent cross-check of the DAMA/LIBRA result by using the same target material, NaI crystals, operated as scintillating calorimeters.
By measuring both temperature and light the NaI crystals in COSINUS will be able to distinguish between electron and nuclear recoils on an event-by-event basis. However, background events induced by cosmic-rays, environmental radioactivity or the intrinsic contamination of the materials used in the crystal, shielding and infrastructure can pose an issue to any analysis and must be mitigated as well as possible. We report on the status of the development and simulations for an active water Cherenkov muon veto, as well as the results of a comprehensive radiogenic material screening.
We use a combination of density functional and effective field theories to calculate the electronic structure of materials that are promising detectors for light dark matter and to predict the corresponding signal rates. Since light dark matter particles are more likely to interact with electrons in materials than to kinematically excite the atomic nuclei that were the focus of searches to date, an accurate description of the detector material's electronic structure is essential. Density functional theory provides such a description through explicit solution of the many-body Schrödinger equation, within a mean-field treatment of the inter-electronic exchange and correlations. We present calculated scattering rates for dark matter -- electron scattering in existing semiconductor detectors, allowing us to exclude some regions of possible dark-matter phase space, and explore carbon-based materials for possible future detectors.
The Hyper-Kamiokande (HyperK) experiment, currently under construction, is expected to conduct precise measurements of the Diffuse Supernova Neutrino Background (DSNB). This requires all backgrounds to be well understood. A possible source of background that has not been considered so far is that from sub-GeV dark matter (DM) which annihilates into neutrinos. We conduct dedicated simulations of the HyperK detector and quantify the extent to which this can happen. We find that the presence of DM could alter the extraction of the correct values of the parameters of interest for DSNB physics. Since the DSNB is an isotropic signal, and DM originates primarily from the Galactic Centre, we show how this effect can be mitigated against with an on-off analysis.
CaWO4 is a well known target material for the search for Dark Matter (DM) via nuclear recoils caused by the scattering of potential DM particles. It was established as such and is famously used by the CRESST experiment, which has a detection sensitivity down to the 20 eV-scale for nuclear recoils. At this energy scale, a reliable simulation of the signal and its background is crucial.
The recently started ELOISE project will provide reliable simulations of electromagnetic particle interactions in CaWO4 down to O(10eV). However, all standard simulation packages have higher applicability limits. Furthermore, even at this “high” energy, the accuracy is only assessed for few materials but not CaWO4. Within a time scale of four years, ELOISE plans to tackle this issue in a two-stage process: First, to evaluate the accuracy and second, if needed, to develop bespoken simulation code with increased accuracy.
In this contribution we motivate the necessity for reliable sub-keV simulations, identify the resulting challenges, outline ELOISE’s approach to overcome them and report the status of ongoing evaluation efforts.
There are various mechanisms by which energy can be accumulated and stored in materials and later released. Examples include thermally induced luminescence and delayed luminescence/after-luminescence in many materials. Interactions between excitations, defects, or other configurations carrying excess energy can lead to avalanche relaxation or other effects, from small correlations in photon or electron emission during an energy release to self-organization or self-replication effects in systems with energy flow. There is no general theory for these dynamic effects, so one must carefully study and analyze phenomenology in different materials and detectors. We tried to reproduce and further study the energy accumulation and release effects in NaI(Tl) first published by Saint Gobain company - that mild exposure to UV light results in the emission of luminescence pulses at Hz rate, persisting for hours to days after exposure. In the St-Gobain study, these pulses were similar to the response induced by 6-10 keV electrons. We have observed luminescence well over a steady-state background, lasting for days after exposure to UV light. We also observed an increase in luminescence hours after exposure to Co60 source. Our findings differ from St. Gobain's observations: exposure to UV results mainly in an uncorrelated flux of single photons above the background without clear evidence for distinct few-photon events in this photon stream. Exposure to red light suppresses these delayed luminescence effects. Detailed analysis and experimental investigation of uncorrelated delayed light emission and possible correlations/photon bunching at lower "afterglow" intensities are required further to understand our results and the St. Gobain observations. Importantly, environmental factors could modulate excitation quenching and interactions between excitations. Monitoring the average photon flux and searching for correlations/photon bunching, polarization, or directionality of delayed photon emission is required to get more insight into the mechanisms for delayed light production and possible delayed heat/temperature spikes production.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-835895-DRAFT
The XENON Dark Matter Project uses a dual phase time projection chamber filled with liquid xenon to search for Dark Matter in the form of weakly interacting massive particles (WIMPs). The current iteration, the XENONnT experiment with 8.6 t of xenon, is taking science data and will also allow the investigation of other science topics due to its extremely low background especially for low energies.
The energy deposition as well as the three-dimensional location of an event in the detector is reconstructed using the fast scintillation light signal and a delayed charge signal. The latter is converted into a light signal by electroluminescence in the gaseous xenon phase above the liquid. The size of the primary scintillation light and of the charge signal are anti-correlated. This poster will outline the energy calibration of the XENONnT experiment using several mono-energetic gamma sources that can be found in the background data as well as in dedicated calibration data using external and internal sources.
This work is supported by BMBF under contract 05A20PM1 and by DFG within the Research Training Group GRK-2149.
In the search for dark matter particle candidates, the mass region below 1 GeV/c2 is mainly unprobed. Utilizing a low-noise silicon sensor as sensitive volume, we aim to detect the signal from an inelastic scattering between such a particle and a bound electron within the silicon. As the deposited energy is only a few eV of energy, a sensor capable of detecting such low signals is required. We are presenting first measurements on a small prototype matrix. It is based on the DePFET repetitive non destructive readout and provides low readout noise of 0.2 e- and below.
The most massive satellite galaxy of the Milky Way (MW) is the Large Magellanic Cloud (LMC) at a distance of roughly 50 kpc. Parent and satellite galaxy form a dynamical system in which gravitational interactions induce non-equilibrium effects and features that alter the equilibrium expectations for the morphology of the dark matter (DM) halos hosting the baryonic components of both objects. The dynamical response caused by the passage of the LMC through the MW hence affects the prospects for direct and indirect searches for DM.
Utilising a set of state-of-the-art numerical simulations of the evolution of the MW-LMC system, we derive the DM distribution in both galaxies at the present time based on the Basis Function Expansion formalism. Consequently, we build $J$-factor all-sky maps of the MW-LMC system in order to study the impact of the LMC passage on gamma-ray indirect searches for thermally produced DM annihilating in the outer MW halo as well as within the LMC halo standalone. We conduct a detailed analysis of 12 years of Fermi-LAT data that incorporates various large-scale gamma-ray emission components and we quantify the systematic uncertainty associated with the imperfect knowledge of the astrophysical gamma-ray sources. We find that the dynamical response caused by the LMC passage can alter the constraints on the velocity-averaged annihilation cross-section for weak scale particle DM at a level comparable to the existing observational uncertainty of the MW halo's density profile and total mass.
LUX-ZEPLIN (LZ) is a dual-phase xenon time projection chamber (TPC) designed to achieve sensitivity to a WIMP-nucleon spin-independent cross section of 1.4 × 10−48 cm^2 at a WIMP mass of 40GeV/c^2 after a livetime of 1000 live days. One of the key strengths of a dual-phase TPC is the use of both an electroluminescence and scintillation signal to discriminate signal from background, as well as to discriminate electron recoils from nuclear recoils. However, there is a non-negligible probability of an isolated electroluminescence and scintillation signal inside the LZ TPC being incorrectly identified as a scattering event. These accidental coincidence backgrounds are heavily dependent on detector geometry, are difficult to predict in advance of operation, and decrease the sensitivity of any dual-phase experiment. This poster details some sources of isolated signals within LZ, along with a number of methods of reducing these signals, which will be applied to the first science run of LZ data.
Experimentalists strive to better analyse signals of dark matter direct detection at detectors. Thus, improved theoretical models are being developed to describe WIMP-nucleus elastic scattering. Notably, the work of Fitzpatrick et al [1,2] utilises an extended list of non-relativistic effective field theory (EFT) nuclear operators. We build on this work by investigating the sensitivity of said nuclear responses to nuclear structure, using nuclear shell model interactions which differ from those used in [1,2] and comparing both sets of results.
To facilitate this comparison, we perform state-of-the-art nuclear shell model calculations for isotopes relevant to direct detection experiments:$^{19}F$, $^{23}Na$, $^{28, 29, 30}Si$, $^{40}Ar$, $^{127}I$, $^{70,72,73,74,76}Ge$ and $^{128, 129, 130, 131, 132, 134, 136}Xe$. Our integrated nuclear response values sometimes exhibit large (up to orders-of-magnitude) factor differences compared to those in [1,2] for certain WIMP-nucleus interaction channels and their associated isotopes. We highlight the potential uncertainties that may arise from the nuclear components of WIMP-nucleus scattering amplitudes due to nuclear structure theory and modeling. This enables us to deduce the effect of these uncertainties on the scattering cross-section.
[1] A. Liam Fitzpatrick et al. “The effective field theory of dark matter direct detection”. In: Journal of Cosmology and Astroparticle Physics (2013). issn: 14757516. doi: 10.1088/1475-7516/2013/02/004.
[2] Nikhil Anand, A. Liam Fitzpatrick, and W. C. Haxton. “Model-independent WIMP Scattering Responses and Event Rates: A Mathematica Package for Experimental Analysis”. In: (2013). doi: 10.1103/PhysRevC.89.065501. url: http://arxiv.org/abs/1308.6288
A main goal of current low background physics is the search for rare and novel phenomena beyond the Standard Model of particle physics. The researched processes are for example the scattering off of a potential Dark Matter particle inside a CaWO4 crystal of the CRESST experiment or the neutrinoless double beta decay of Ge nucleus for the future Legend experiment. Success of such experiments depends on a reliable background prediction through the use of Monte Carlo simulations to predict the event rate associated with the different background sources. A widely used toolkit to construct these simulations is Geant4, where a wide choice of physics models is available in different predefined physics lists. In this work, we examine the impact of different physics lists on the total energy deposition for several configurations of our test case, i.e., combinations of radioactive contaminants, target material (CaWO4 and Ge) and target thickness. Quantitative comparison between simulated datasets is performed by appropriate statistical tests.
With much of the dark matter candidate parameter space still unexplored, novel detection technologies enable searches for previously inaccessible viable candidates. In particular, methods which exploit directional discrimination will allow for unambiguous confirmation of a galactic signal. Nano- and micro-particles, cooled and levitated in isolation within high vacuum, open up the potential for extremely sensitive measurements of weak forces at both short and long range. We present the first results from our levitated optomechanical direct dark matter experiment, which is capable of resolving collisions in all three dimensions. It utilises levitated nanoparticles (10^-18 kg) for composite dark matter searches in the 10 MeV – 10 GeV mass range. We describe the current experimental apparatus and methodology used in our search, and present sensitivity projections competitive with world-leading dark matter constraints, informed by an initial characterisation of relevant backgrounds. We also outline planned improvements and alternative experimental setups which will aid in these searches into unexplored dark matter parameter space.
Whereas weakly interacting massive particles (WIMPs) - a promising DM candidate - were intensively studied in the past, the theory of strongly interacting massive particles (SIMPs) has been comparably less investigated. A possible way to generate such SIMPs is through chiral symmetry breaking, similar to the production of pions in QCD. We consider a dark gauge group $\text{Sp}(4)$ and $N_f=2$ fermions in the pseudo-real fundamental representation. In absence of the mass term in the Lagrangian, a global flavor symmetry is present. Whenever a continuous global symmetry is broken, the Goldstone theorem guarantees the existence of low-energy massless Goldstone bosons. The dynamics of these bosons is described by the chiral Lagrangian (low energy effective theory). However, in presence of a mass term, the flavour symmetry is explicitly broken and the Goldstone bosons - SIMPs - gain non-zero masses. We determine the chiral Lagrangian with the inclusion of the Wess-Zumino-Witten term for degenerate and non-degenerate flavors. We analyse the breaking patters and mutiplet structure including a coupling to the Standard Model with a dark $\text{U(1)}$ sector. This opens the door to phenomenology. In addition, we introduce vector and axial-vector states of the theory. The complete model is supported by lattice simulations.
We study the relic abundances of stable particles from a generic dark sector in the presence and absence of initial dark asymmetries, and find out that abundances are expected to be of similar magnitude, i.e. multi-component dark matter is quite natural. We first discuss the different possibilities for stabilizing multi-component dark matter and then analyze the final relic abundances of the symmetric and asymmetric dark matter components in the presence of unavoidable conversions between dark matter states. We find an exponential dependence of the asymmetries on annihilation and conversions for the heavier components. We conclude that having similar symmetric and asymmetric components is a quite natural outcome of scenarios with several stable particles. This has novel phenomenological implications, which we discuss.
The CRESST-III experiment specialises on the direct search for low-mass dark matter. The analysis of the CaWO4 detector called “detector A”, operated in Run34, provided world-leading limits in the sub- GeV mass range. To interpret the residually observed events, the existence of a background model is crucial. Neutron-induced nuclear recoils are similar to the sought-for DM-induced nuclear recoil signal and as such, they are an important ingredient to this model.
In this contribution, we present the simulation based neutron background model for the CRESST-III experiment, in the context of the published detector A results, and discuss the probability of obtaining a nuclear recoil contribution to the residual events.
Furthermore, a simulation of the neutron calibration revealed interesting features in the energy deposition spectrum due to thermal neutron capture reactions. A discussion of these features and their potential purpose in future experimental runs is additionally discussed in this poster.
Paleo-detectors are a proposed alternative approach to the direct detection of Dark Matter. In lieu of using large target masses to search for nuclear recoils in real time, the idea behind paleo detectors is to use small detectors that could integrate signals from nuclear recoils over large timescales to achieve the necessary exposure for Dark Matter searches. Natural minerals found on Earth have formed as long as two gigayears ago, and many of these minerals are excellent solid state track detectors. In this talk I will present a number of possible use cases of measurements of nuclear recoil tracks in such natural samples: Paleo detectors could be used to search for Dark Matter as well as for solar, supernova, and atmospheric neutrinos. By using a collection of paleo-detectors of different ages one could furthermore obtain information about the time-evolution of the signal rate over 10 Myr -- 1 Gyr timescales. This would open up unique possibilities to explore Dark Matter substructure in our galaxy and to track the evolution of our Sun, the Milky Way's star formation history, and the low-energy cosmic ray flux on Earth over these timescales.
The DAMA experiments have detected a modulating signal compatible with dark matter for 20 years with a combined significance of 12.9 sigma. A result in tension for a spin independent WIMP with null results from large noble gas experiments. This is the motivation for NaI(Tl) based replication studies of the DAMA experiment.
One of the biggest challenges facing these experiments is the low number of photoelectrons detected at the 1 keV$_{ee}$ lower threshold. This reduces the efficiency of the detector and makes distinguishing scintillation events from photomultiplier noise difficult. This noise is a significant component of the low energy background model that is difficult to include in time dependent background models as it cannot be modelled in Monte Carlo simulations. This makes accurate measurement of the low energy noise important for both understanding and minimising its contribution to the overall background.
We report on the photomultiplier characterisation test bench developed for the crystal detector photomultipliers for the SABRE (Sodium iodide with Active Background Rejection) South experiment, a detector designed to test the DAMA modulation. This includes studies of the single photon response, quantum efficiency, dark noise and detector linearity. A specific focus is on correlated dark noise between two photomultipliers above the random coincidence rate, due to its significant contribution to the low energy background. We have also begun development of signal vs. noise classifiers for low energy scintillation events base on a selection of pulse shape variables.
We present the results of the photomultiplier characterisation and its impact on the low energy performance of the SABRE South experiment. We also present initial measurements of the first SABRE South test crystal grown from Astro-Grade NaI powder, which has undergone direct background counting.
Travelling-wave kinetic inductance parametric amplifiers (KIPAs) are cryogenic quantum-noise limited devices with O(10) dB gain over an octave or more of bandwidth, making them well suited for microwave domain astroparticle measurements. We present results from an experiment coupling a 4-8 GHz KIPA to a dish and antenna system to search for hidden-photon dark matter candidates. A cryogenically cooled reflector focuses hidden-photons onto a horn antenna, which is then amplified by the KIPA. The broadband nature of the reflector experiment neatly couples to the broadband amplification provided by KIPAs and we demonstrate a first probing of the hidden-photon kinetic mixing parameter $\epsilon$ down below $10^{-12}$ for hidden-photon masses between 20-30 μeV. We discuss relevant experimental challenges and present a roadmap to achieving $\epsilon$ sensitivity down to $10^{-14}$ for frequencies up to a THz.
Dark matter (DM) accounts for 85% of the matter in our universe, however, its nature is still one of the biggest open questions in modern physics. While measurements have imposed strong limits on the spin-independent scattering of DM in direct detection experiments, the parameter space of spin-dependent scattering still leaves room for exploration. CRESST-III operated in their latest run for the first time lithium aluminate crystals as cryogenic, scintillating calorimeters, optimized for DM searches, in the low background environment of the Laboratori Nationali del Gran Sasso (LNGS). In previous above ground measurements with lithium targets, promising constraints on the cross section of spin-dependent DM interactions could already be set. In my presentation I discuss the obtained results with lithium targets, the details on the analysis chain and future perspectives.
Construction of the COSINUS experiment is quickly progressing at the LNGS underground laboratory. In this contribution, we will present the experimental setup of the COSINUS rare event search, which aims at providing a crosscheck of the signal reported by the DAMA/LIBRA collaboration using NaI as a cryogenic absorber material. The scintillating bolometers of COSINUS will be operated in a dry dilution cryostat, surrounded by a water Cherenkov muon veto, and operated in a low-background environment at LNGS. We will illustrate key elements of the facility currently being built, and give an overview on the current status of construction, which is already mostly complete.
In this study, we calculated the effect of self-interacting dark matter on neutron stars. Properties like the mass, radius and the tidal deformability are affected by the presence of dark matter in neutron stars. We show that the Love number can be used to probe the presence and the properties of dark matter inside of neutron stars in future gravitational wave measurements.
Large efforts are being made to directly detect interactions of Dark Matter with ordinary matter, including the Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) experiment located at the Labor- atori Nazionali del Gran Sasso (LNGS) in Italy. During the second phase of the experiment, CRESST-II, scin- tillating CaWO4 target crystals were used to detect nuclear recoils. However, at low energies a distinction be- tween Dark Matter recoils and beta-particles/gamma-rays is hardly possible. It is therefore vital to understand the composition of ambient radioactive background in the experimental reference data as it can be used in an analysis that allows to check for possible Dark Matter signals.
Tackling this problem, a first Monte Carlo electromagnetic background model was developed for CRESST-II in a predecessor study, where sources of contamination (radiogenics and cosmogenics) were identified and simu- lated for the detector module named TUM40. The resulting spectral templates were scaled using parametric Gaussian templates that were fitted to obvious peaks in the experimental data. The remaining flat energy spectra, that lack distinct alpha- or photopeaks, were scaled using a steady-state condition known as secular equilibrium.
The techniques presented in this work aim at improving CRESST’s background model by using a more detailed implementation of the experimental geometry, including more components into the model (more cosmogenic nuclides and more detector parts), using a template fitting method based on Bayesian likelihood and the Metrop- olis-Hastings algorithm, and by simultaneously fitting another detector module, called Lise, from the same run.
The results of a fit with 206 free parameters are presented, showing a significant increase of the reproduction in the energy range 1 keV–40 keV from 68% in the predecessor study to over 97% in this work. Finally, an over-
view of the current developments and considerations to improve upon the predecessor model are presented.
Warm dark matter (WDM) could explain some small-scale structure observations that have challenged the cold dark matter (CDM) model, as warm particles suppress structure formation due to free streaming effects. Observing small-scale structure thus provides a valuable way to distinguish between CDM and WDM. In this talk, I will present a semi-analytical model of the dark matter substructure evolution, with which we estimated the number of satellite galaxies in the Milky Way. I will discuss stringent constraints on WDM models based on the observed number of satellites in the Milky Way.
Moreover, warm particles such as sterile neutrinos and axion-like particles can decay into photons, which are consequently detectable by X-ray telescopes. eROSITA will perform an all-sky X-ray survey, of which I will present its sensitivity to identify dark matter decay with narrow X-ray line emission.
Dual-phase noble liquid time-projection chambers have a long application history in searches for rare low-energy events like interactions with dark matter particles. Because of scalability and existing support infrastructure, they are expected to serve in large future projects. Our analysis of data and models for electrons and ions extraction from the liquid into the gas phase and data for the dwelling time of unextracted electrons at the liquid surface indicates that several remarkable effects, including Wigner crystallization of unextracted electrons on the liquid surface, which can be present. Not checking for these effects could lead to systematic uncertainties in particle physics results analysis. Though additional studies on the detector’s physics are required, we can suggest some detector design improvements.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-834584-DRAFT
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In the presence of radiation from bright astrophysical sources at radio frequencies, axion dark matter can undergo stimulated decay to two nearly back-to-back photons, meaning that bright sources could have a counterimage (''gegenschein'') in nearly the exact opposite spatial direction if axions comprise the dark matter. The counterimage will be spectrally distinct from backgrounds, taking the form of a narrow radio line centered at half the axion mass with a width determined by Doppler broadening in the halo. I will discuss how the axion decay-induced echoes of supernova remnants may be bright enough to be detectable with ongoing observations from the FAST radio telescope.
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Searches for light dark matter (DM) imply the detection of sub-keV nuclear recoils. However, an absolute energy calibration in this regime is still missing. The CRAB project proposes a method based on nuclear recoils induced by the emission of MeV-$\gamma$-rays following thermal neutron capture. Single MeV-$\gamma$ transitions are of particular interest as they induce well-defined nuclear recoil peaks in the 100 eV-1 keV range for many different materials. The proposed method offers the only direct calibration of pure nuclear recoils so far. With detailed GEANT4 simulations, we studied the expected energy spectrum in various cryogenic detectors used for DM search. For a cryogenic CaWO$_4$ detector, similar to the ones used in the CRESST experiment, clear nuclear recoil calibration lines at 112 eV and 160 eV are predicted.
Currently, we are preparing a proof-of-concept measurement with a portable neutron source at the Technical University of Munich. For a precision measurement, the low power TRIGA reactor in Vienna will provide a clean beam of thermal neutrons. In the first phase, the CRAB project foresees to perform a precise nuclear recoil calibration of cryogenic CaWO$_4$ detectors read-out with a W-TES. In the second phase, additional tagging of the $\gamma$-rays produced in the de-excitation process will allow to extend the calibration method below 100~eV and to a wider range of detector materials, such as germanium or silicon. Combined with an electronic recoil calibration, CRAB will allow to measure energy quenching in the sub-keV regime. With its novel idea, CRAB provides a direct and accurate calibration of nuclear recoils in the region of interest of light DM experiments, which is essential for finding and studying new physics. Latest simulation results and the experimental strategy will be presented.
Potassium-40 (K$^{40}$) is a long-lived, naturally occurring radioactive isotope. This radionuclide decays mainly by beta emission to calcium, and by electron-capture to an excited state of argon. An additional electron-capture of K$^{40}$ to the ground state of argon theoretically exists but has never been experimentally observed. Predicted intensities are highly variable (0-0.8%) and this decay channel can be an important background for many rare-event searches, especially those involving NaI-based scintillators (ex. DAMA, ANAIS-112, COSINE-100, SABRE, COSINUS etc..). KDK (Potassium (K) Decay (DK)) is an international collaboration dedicated to the first measurement of this branching ratio. The experiment is performed using a silicon drift detector with a thermally deposited, enriched K$^{40}$ source inside the Modular Total Absorption Spectrometer (MTAS, Oak Ridge National Laboratory). MTAS is a large NaI detector whose high gamma-ray efficiency enables the proper discrimination between ground and excited state electron capture events. This setup has been characterized in terms of energy calibration, tagging efficiency and dead time. We report on our latest experimental results and the process of opening the blind data set.
The CRESST-III (Cryogenic Rare Event Search with Superconducting Thermometers) experiment aims at the direct detection of dark matter particles via their elastic scattering off nuclei in a scintillating CaWO4 target crystal. The CaWO4 crystal is operated together with a light detector at O(mK) temperature and read out by a tungsten Transition-Edge-Sensor. For many years these CaWO4 target crystals have successfully been produced in-house at the Technical University of Munich with a focus on a low level of radioactive impurities in the crystals. This is crucial to reduce backgrounds in the region of interest originating from radioactive decays. In order to further improve the CaWO4 crystals, an extensive chemical purification of the raw materials and the synthesized CaWO4 powder has been performed. In addition, a temperature gradient simulation of the growth process and subsequently an optimization of the growth furnace with the goal to reduce the intrinsic stress was carried out.
The crystal TUM93 was grown from this purified powder in the optimized furnace. The poster will present results from the detector module TUM93A which is currently being operated in the ongoing CRESST run.
A major hurdle in searches for sub-GeV particle-like dark matter is demonstrating sufficiently low energy detection thresholds in order to detect recoils from light dark matter particles. Many detector concepts have been proposed to achieve this goal, which often include novel detector target media or sensor technology. A universal challenge in understanding the signals from these new detectors and enabling discovery potential is characterization of detector response near threshold, as the calibration methods available at low energies are very limited. We have developed a cryogenic device for robust calibration of any photon-sensitive detector over the energy range of 0.62-6.89eV. This device can be used to scan over a detector and deliver narrowly-collimated pulses of small numbers of photons in a way that limits parasitic backgrounds, allowing for exploration of a variety of science targets including position sensitivity of detector configurations, phonon transport in materials, and the effect of quasiparticle poisoning. In this talk, I will present the design overview and specifications, along with current status of the testing program.
Astroparticle physics experiments often face unknown backgrounds, e.g. at low energies or near detector edges. This talk introduces the deficit hawk technique, which mitigates unknown backgrounds by testing multiple options for data cuts simultaneously. This can double the physics reach of experiments with partial or speculative background knowledge, and simplifies decisions on fiducial volumes or energy thresholds. Deficit hawks are well-suited to analyses that use machine learning or multidimensional likelihoods, and permit discoveries in regions without unknown backgrounds.
The expected signal from solar and atmospheric neutrinos looms as a future background for direct dark matter experiments. Misinterpreting this background would have huge implications for dark matter searches. This is because possible modifications to neutrino interactions remain possible. By measuring neutrinos at direct detection experiments we will be able to probe these modifications proving an independent test of physics beyond the Standard Model. In Eur. Phys. J. C81 (2021) 861., collaborators and I showed that direct detection experiments will be pivotal in confirming the $U(1)_{L_\mu-L_\tau}$ solution to the measured tension in the muon’s anomalous magnetic moment. These experiments will provide us with unique information for neutrino physics, and the principle is more far-reaching than this one timely example. I will present ongoing work which assesses the impact upcoming direct detection experiments will have on non-standard neutrino interactions more generally.
This talk will follow Eur. Phys. J. C81 (2021) 861. and an upcoming paper.
A large flux of axion-like particles can be produced in the solar core. While the majority of these particles will have high velocities and escape the Sun’s gravitational pull, a small fraction of low-velocity particles will become trapped on bound orbits. Over time, an appreciable density of slow-moving axions can accumulate in this “solar basin.” Their subsequent decay to two photons provides a distinct observational signature. I will present a recent analysis using data taken by the NuSTAR X-ray telescope to search for the decay products of keV-scale axions trapped in the solar basin. Our results ultimately set limits on the axion-photon and axion-electron couplings well over an order of magnitude beyond current constraints and motivate the further exploration of stellar basins in other astrophysical systems.
Axion-photon conversion is a prime mechanism to detect axion-like particles that share a coupling to the photon. We point out that in the vicinity of neutron stars with strong magnetic fields, magnetars, the effective photon mass receives comparable but opposite contributions from free electrons and the radiation field. This leads to an energy-dependent resonance condition for conversion that can be met for arbitrary light axions and leveraged when using systems with detected radio components. I discuss the sensitivity of the method and its potential to improve current constraints on the axion-photon coupling over a broad mass range. I suggest that the method hosts a serious potential in the search for axion-like particles
The electromagnetic interactions of axions can be dramatically enhanced in the magnetospheres of neutron stars as a result of the large magnetic fields and the dilute plasma. In this talk I will discuss the various processes which can give rise to distinct signatures of axions in these environments; this includes: (1) the resonant transition of axion dark matter to nearly monochromatic radio photons, (2) the production of axions from the plasma dynamics in the polar caps of neutron stars, and (3) the generation and implications of axion bound states. I will conclude by highlighting recent efforts on the observational side, which have led to world-leading limits on micro-eV scale axion dark matter.
Neutron stars can host strong electromagnetic fields deep in their magnetospheres capable of sourcing axions. Low mass axions are produced relativistically and can resonantly convert into radio photons as they escape the magnetosphere. For heavier axions an increasing fraction will instead end up populating a cloud of bound states around the parent neutron star. In this talk I will discuss the fundamental physics driving both axion production and conversion in these scenarios, followed by an end-to-end analysis pipeline that facilitates an accurate description of the prospective radio flux. This is finally compared with radio observations of nearby pulsars to derive stringent constraints on the axion-photon coupling.
In this talk, I will discuss a novel electromagnetic signal for two well-motivated ultralight dark-matter (DM) candidates: dark photons and axion-like particles (ALPs). The signal is a small (but larger than expected) oscillating magnetic-field pattern that appears across the entire surface of the Earth, driven by the DM field. It is highly phase-coherent and has a frequency set by the DM mass, with the specific signal pattern depending on the DM candidate. I will discuss searches for this signal that leverage the exceptional utility that distributed magnetometer networks hold as fundamental-physics discovery tools. In particular, I will discuss how my collaborators and I searched for this signal using an existing dataset maintained by the SuperMAG Collaboration, consisting of unshielded magnetometer readings taken at O(500) geographically distributed geomagnetic ground stations. These data have one-minute time resolution, with the earliest data taken in 1970. Our search finds no robust evidence for either DM candidate. However, we place the first direct exclusion bounds on dark-photon DM in the mass-range from $2\times 10^{-18}$ eV to $7\times 10^{-17}$ eV; these limits are complementary to existing astrophysical bounds. For ALP DM, we place limits in the same mass range that at some masses rival existing laboratory constraints on axions. I will mention ongoing work and future plans to extend these searches.
The excess of gamma rays in the data measured by the Fermi Large Area Telescope from the Galactic center region is one of the most intriguing mysteries in Astroparticle Physics. This Galactic center excess (GCE), has been measured with respect to different interstellar emission models, source catalogs, data selections and techniques. Although several proposed interpretations have appeared in the literature, there are no firm conclusions as to its origin. The main difficulty in solving this puzzle lies in modeling a region of such complexity and thus precisely measuring the characteristics of the GCE. In this presentation I will show the results obtained for the GCE by using 11 years of Fermi-LAT data, state of the art interstellar emission models, and the newest 4FGL source catalog to provide precise measurements of the energy spectrum, spatial morphology, position, and sphericity of the GCE. I will also present constraints for the interpretation as dark matter particle interactions using the GCE, a gamma-ray analysis of dwarf spheroidal galaxies with LAT data and AMS-02 cosmic-ray antiprotons and positrons flux data.
The Galactic center excess (GCE) remains one of the most intriguing discoveries from the \textit{Fermi} Large Area Telescope (LAT) observations. I will revisit the characteristics of the GCE by first producing a new set of high-resolution galactic diffuse gamma-ray emission templates. This diffuse emission, which accounts for the bulk of the observed gamma rays, is ultimately due to cosmic-ray interactions with the interstellar medium. Using recent high-precision cosmic-ray observations, in addition to the continuing \textit{Fermi}-LAT observations and observations from lower energy photons, we constrain the properties of the galactic diffuse emission. I will describe a large set of diffuse gamma-ray emission templates which account for a very wide range of initial assumptions on the physical conditions in the inner galaxy. We find a high-energy tail for the GCE at higher significance than previously reported. This tail is very prominent in the northern hemisphere, and less so in the southern hemisphere. This strongly affects one prominent interpretation of the excess: known millisecond pulsars are incapable of producing this high-energy emission, even in the relatively softer southern hemisphere, and are therefore disfavored as the sole explanation of the GCE. The annihilation of dark matter particles of mass $40^{+10}_{-7}$ GeV (95$\%$ CL) to $b$ quarks with a cross-section of $\sigma v = 1.4^{+0.6}_{-0.3} \times 10^{-26}$ cm$^{3}$s$^{-1}$ provides a good fit to the excess especially in the relatively cleaner southern sky. Dark matter of the same mass range annihilating to $b$ quarks or heavier dark matter particles annihilating to heavier Standard Model bosons can combine with millisecond pulsars to provide a good fit to the southern hemisphere emission as well, as can a broken power-law spectrum which would be related to recent cosmic-ray burst activity.
We present a new reconstruction of the distribution of atomic hydrogen in the inner Galaxy that is based on explicit radiation-transport modelling of line and continuum emission and a gas-flow model in the barred Galaxy that provides distance resolution for lines of sight toward the Galactic Center. The main benefits of the new gas model are, a), the ability to reproduce the negative line signals seen with the HI4PI survey and, b), the accounting for gas that primarily manifests itself through absorption.
We apply the new model of Galactic atomic hydrogen to an analysis of the diffuse gamma-ray emission from the inner Galaxy, for which an excess at a few GeV was reported that may be related to dark matter. We find with high significance an improved fit to the diffuse gamma-ray emission observed with the Fermi-LAT, if our new HI model is used to estimate the cosmic-ray induced diffuse gamma-ray emission. The fit still requires a nuclear bulge at high significance. Once this is included there is no evidence for a dark-matter signal, be it cuspy or cored. But an additional so-called boxy bulge is still favoured by the data. This finding is robust under the variation of various parameters, for example the excitation temperature of atomic hydrogen, and a number of tests for systematic issues.
We estimate the sensitivity of the Cherenkov Telescope Array (CTA) to detect diffuse gamma-ray emission from the Perseus galaxy cluster, both from interactions of cosmic rays (CR) with the intra-cluster medium, and as a product of annihilation or decay of dark matter (DM) particles in case they are weakly interactive massive particles (WIMPs). The observation of Perseus constitutes one of the Key Science Projects proposed by the CTA Consortium for the first years of operation of the CTA Observatory. In this talk, we will focus on the DM-induced component of the flux. Our DM modeling includes the substructures we expect in the main halo of Perseus, as predicted within the standard cosmological model hierarchical structure formation scenario, which will "boost" the annihilation signal significantly. We compute the expected CTA sensitivity using a likelihood maximization analysis using the most recent CTA instrument response functions. We also model the expected CR-induced gamma-ray flux in the cluster, and both DM- and CR-related uncertainties via nuisance parameters. We will show the sensitivity of CTA to discover diffuse gamma-rays in a galaxy clusters for the first time. Even in absence of a signal, we show that CTA will allow us to provide stringent and competitive constraints on TeV DM, that will rely on state-of-the-art modeling of the cluster's DM distribution. Finally, we will discuss the optimal strategy for CTA observations of Perseus.
Galaxy clusters are the largest virialised objects in the Universe and, as such, have high dark matter (DM) concentrations. This abundance of dark matter makes them promising targets for indirect DM searches.
Here we report the details of a search, utilising almost 12~years of Fermi/LAT data, for gamma ray signatures from the pair annihilation of WIMP dark matter in the GeV energy band. From this, we present the constraints on the annihilation cross-section for the $b\overline{b}$, $W^+W^-$ and $\gamma\gamma$ channels, derived from the non-detection of a characteristic signal from five nearby, high galactic latitude, galaxy clusters (Centaurus, Coma, Virgo, Perseus and Fornax). We discuss the potential of a boost to the signal due to the presence of substructures in the DM halos of selected objects, as well as the impact of uncertainties in DM profiles on the presented results. We assert that the obtained limits are, within a small factor, comparable to the best available limits of those based on Fermi/LAT observations of dwarf spheroidal galaxies.
Feebly interacting particles (FIPs), such as axion-like particles, sterile neutrinos and dark photons, with masses O(10–100) MeV can be efficiently produced in core-collapse supernovae and escape the supernova envelope. During propagation in the interstellar medium, these particles may decay into electron-positron pairs, generating a positron flux. Such positrons would annihilate with electrons in the Galactic medium and contribute to the photon flux in the 511 keV line. Using the spectrometer on INTEGRAL observation of this line improves the bounds on the couplings for these particles by several orders of magnitude below what is already excluded by the SN 1987A energy-loss argument.
NA61/SHINE is a large-acceptance fixed-target experiment located at the CERN SPS, which studies final hadronic states in interactions of various particles and nuclei. It is unique in terms of providing data on a variety of collision systems at different collision energies. This allows for wide deuteron, antiproton and antideuteron production cross-section studies. The latter are currently considered a possible dark matter interaction signal with exceptionally small background. The measurements on carbon targets are important to reduce systematic experimental effects due to experiment-internal antideuteron production, as the most abundant element in the path of an incoming particle for the AMS-02 experiment is carbon. My talk will focus on analysis of NA61/SHINE data on p+C thin target collisions in the context of light (anti)nuclei production. I will present a preliminary analysis of experimental data and discuss quality cuts and the particle identification method as well as current deuteron and antideuteron yields.
The presence of a non-baryonic Dark Matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. If DM interacts weakly with Standard Model (SM) particles it could be produced at the LHC. The ATLAS experiment has developed a broad search program for DM candidates in final states with large missing transverse momentum produced in association with other SM particles (light and heavy quarks, photons, Z and H bosons, as well as additional heavy scalar particles). The results of recent searches on 13 TeV pp data, their interplay and interpretation will be presented.
The study of the 125 GeV Higgs boson can open a window of sensitivity to a new dark sector. Results of searches for both prompt and non-prompt decays of the Higgs boson into new dark sector particles in 13 TeV pp collisions with the ATLAS detector are presented. Searches that encompass a wide range of new particle masses, lifetimes and degrees of collimation of decay products are discussed.
Searches in CMS for dark matter in final states with invisible particles recoiling against visible states are presented. Various topologies and kinematic variables are explored, including jet substructure as a means of tagging heavy bosons. In this talk, we focus on the recent results obtained using the full Run-II dataset collected at the LHC.
The MoEDAL experiment deployed at IP8 on the LHC ring was the first dedicated search experiment to take data at the LHC's Run-2 in 2015. It was designed to search for Highly Ionizing Particle (HIP) avatars of new physics such as magnetic monopoles, dyons, Q-balls, multiply charged particles, massive slowly moving charged particles and long-lived massive charged SUSY particles. This class of particles contribute a number of possible dark matter candidates. We shall report on our search for HIPs at LHC’s Run-2.
The MoEDAL detector is being reinstalled for LHC’s Run-3 to continue the search for electrically and magnetically charged HIPs. As part of this effort we will initiate the search for massive long-very lived SUSY particles to which MoEDAL has a competitive sensitivity. An upgrade to MoEDAL, the MoEDAL Apparatus for Penetrating Particles (MAPP), approved by CERN’s Research Board is now the LHC’s newest detector. The MAPP detector, positioned in UA83, expands the physics reach of MoEDAL to include sensitivity to feebly-charged particles with charge, or effective charge, as low as 10^-3 e (where e is the electron charge). Also, the MAPP detector In conjunction with MoEDAL’s trapping detector gives us a unique sensitivity to extremely long-lived charged particles. MAPP also has some sensitivity to long-lived neutral particles.
Additionally, we will very briefly report on the plans for the MAPP-2 upgrade to the MoEDAL-MAPP experiment for the High Luminosity LHC (HL-LHC). This detector is currently being deployed in the UGC1 gallery near to IP8. This phase of the experiment is designed to maximize MoEDAL-MAPP’s sensitivity to very long-lived neutral messengers of physics beyond the Standard Model. We will discuss how the MAPP extensions to the MoEDAL detector allow MoEDAL to test a number of dark sector models and search for dark matter candidates in this arena.
We investigate how DM searches at the LHC can be improved by Deep Learning techniques. We look at the task of finding semi-visible jets arising from a dark sector model that couples to the SM. Finding this signature has been shown to be difficult compared to multi-prong decays from new heavy resonances. The task can be tackled with varying amount of supervision during training, trading sensitivity for independence of a given signal model. We examine this tradeoff for fully supervised, weakly supervised and unsupervised methods. We find that significant sensitivity boosts are possible also in a model agnostic setup.
The Radiation Damage in CCDs (RADAC) is a collaboration between theorists and experimentalists with expertise in solid state physics, ultra-low noise CCDs (DAMIC-M) and radiation damage (RD50). In the first quarter of 2022, RADAC achieved its first goal of observing radiation damage caused by nuclear recoils in CCDs developed for direct detection of dark matter. Nuclear-recoil events were induced with a neutron source on a CCD and the generated crystal defects were then spatially identified as “hot spots” of leakage current while operating at moderately high temperatures. This same technique could be employed to search for radiation damage caused by dark matter interactions. In this detection channel, the dark matter signal amplitude has a time dependence related to the Earth's rotation and movement through the dark matter cloud. I will present the development of the experimental technique, including results from the recent neutron irradiation campaign, and describe its application for the search of dark matter.
With its increasing statistical significance the DAMA/LIBRA annual modulation signal is a cause for tension in the field of dark matter direct detection. A dark matter explanation for this signal is under standard assumptions incompatible with numerous null-results of other experiments. The COSINUS experiment aims at a model-independent cross check of the DAMA/Libra signal claim.
In order for such a model-independent cross check to be meaningful, the same detector material as used by DAMA has to be employed. Thus COSINUS will use NaI crystals operated as cryogenic scintillating calorimeters at mili-Kelvin temperatures. Such a setup enables independent measurement of both temperature and scintillation light signals via transition edge sensors (TESs). This dual-channel readout allows particle discrimination on an event-by-event basis, as the amount of light produced depends on the particle type (light quenching).
However, the non-standard physical and chemical properties of NaI cause an obstacle when attaching such a TES directly onto the surface of the crystal. This problem can be overcome with the so called “remoTES” design, where the TES itself is attached to an external wafer crystal. Phonons from an interaction in the NaI crystal are then collected in a gold pad coupled to the absorber which is connected to the TES via a gold bonding wire. We present the results from a first successful operation of NaI and other crystals as cryogenic calorimeters with the remoTES design.
Phonon-mediated particle detectors promise sub-eV threshold reach for the increasingly relevant sub-GeV dark matter (DM) parameter space. Kinetic Inductance Detectors (KIDs), exploiting superconducting material physics via Cooper-pair breaking, have particular advantages as the phonon sensors when mounted on crystalline substrates. Their inherent multiplexability, non-dissipative nature, and exponential suppression of quasiparticle population with temperature – assuming a reduction in residual quasiparticles - make them well suited for imaging the entire phonon flux across the substrate. We discuss here efforts in building two kinds of KID based DM detectors and their calibration using an optical LED setup. The first design uses a single Al KID on a gram-scale substrate, with demonstrated O(eV) resolution on energy received. The second design, optimized for background rejection, uses an array of KIDs to resolve both position and discriminate recoil types, with demonstrated O(100) eV energy resolution. We also outline plans to achieve sub-eV resolution in the next generation of devices through both the use of a quantum-limited superconducting parametric amplifier and alternative KID material selection. Finally, we present novel phonon-mediated ideas and techniques for meV-threshold DM detection, focusing on Quantum Capacitance Detectors (QCDs) derived from quantum computing charge qubits.
Developments over the last decade have pushed the search for particle dark matter (DM) to new frontiers, including the keV-scale lower mass limit for thermally-produced DM. Galactic DM at this mass is kinematically matched with the energy needed to break a Cooper pair (~meV), making quantum sensors ideally-suited for DM detection applications. At Fermilab, we are constructing QUIET, a dedicated, underground quantum sensor test facility, which will be used as part of the Quantum Science Center to deploy quantum detectors in a low-background environment. I will discuss the current state of the field as well as plans to leverage this facility for DM detection down to the lower mass limit for thermal production in the early universe.
Ever since the discovery of accelerated expansion, the cosmological standard model $\Lambda$-CDM has been our best description of the universe on large scales. In recent years, however, significant tensions have appeared that cast doubt on the validity of dark matter being a cold non-interacting fluid, and the cosmological constant being a global parameter. Moreover, searches for weakly interacting massive particles at accelerators have so-far not been successful. Therefore, light particles, such as the QCD axion have moved into the spotlight. While there is a vast theoretical landscape of effective models at low energies, there exist general frameworks to classify them. The Wilczek-Moody formalism classifies all possible tree-level interactions between fermions, while Kostelecky's standard model extension provides a comprehensive framework for terms breaking the Lorentz invariance.
Using these frameworks, precision force metrology at low energies can be used to search for the manifestations of hypothetical fifth forces. While traditional torsion balances have long set the standards in this area, the Casimir And Non-Newtonian force EXperiment CANNEX is the world's only force metrology setup operating in the geometry of macroscopic plane parallel plates. In this talk, I will review the technique, status, and prospects of this unique setup in the context of dark matter detection.
Searches for dark matter (DM), using a vast array of different technologies that cover a wide range of DM masses, have consistently returned null results. While most experiments have probed WIMP-like dark matter above a few GeV in mass, models of light (< 1 meV) bosonic dark matter are compelling and large swaths of parameter space remain unexplored. One such model, an ultralight scalar particle that couples to fundamental constants (e.g. electron mass, fine structure constant) will induce time-dependent fluctuations in the energy levels of atoms, which can be detected using precision quantum-mechanical sensors. The Matter-wave Atomic Gradiometer Interferometric Sensor (MAGIS-100), soon to be constructed at Fermilab, will search for various ultralight DM models and new forces using three coupled light-pulsed atom interferometers across a 100-meter baseline. The experiment offers sensitivity to bosonic DM candidates in the mass range of $10^{-22}-10^{-15}$ eV, a region of parameter space that is relatively unconstrained. This detector builds on expertise from the 10-meter prototype at Stanford and capitalizes on the latest advancement in atomic clock technology, and will serve as a pathfinder for a future kilometer-scale sensor. In this talk, I summarize the planned scientific program for the experiment and present projected sensitivities of searches for dark matter and new forces.
Axion-like particles (ALPs) are a broad class of pseudo-scalar bosons that generically arise from broken symmetries in extensions of the standard model. In many scenarios, ALPs can mix with photons in regions with high magnetic fields. Photons from distant sources can mix with ALPs, which then travel unattenuated through the Universe, before they mix back to photons in the Milky Way galactic magnetic field. Thus, photons can traverse regions where their signals would normally be blocked or attenuated.
In this talk, I will present the results, and necessary background, of a paper where we use $\gamma$-ray observations of distant TeV blazars, made by the HAWC collaboration, to constrain models of ALPs. We use 7 TeV upper limits provided by HAWC to find new constraints on the ALP parameter space that are competitive with, or better than, leading terrestrial and astrophysical constraints in the relevant mass range.
Axions and axion-like-particles (ALPs) are well motivated beyond the standard model particles that can explain a variety of unsolved problems in physics, such as the strong CP problem and the nature of dark matter. These particles are characterised by their two-photon coupling, which leads to so-called photon-ALP oscillation as photons propagate through an external magnetic field. Such oscillations will lead to, for instance, characteristic signatures in the energy spectrum of high-energy photons from astrophysical sources, allowing us to probe the existence of ALPs and possibly dark matter. In this talk, we review the signatures ALPs imprint on high energy photon spectra, and we discuss an improved statistical test that searches for the energy-dependence of the oscillations. The focus is on photons at TeV-energies relevant for the upcoming Cherenkov Telescope Array (CTA).
Experimental refinements and technical innovations in the field of extensive air shower telescopes have enabled measurements of Galactic cosmic-ray interactions in the sub-PeV (100 TeV to 1 PeV) range, providing new avenues for the search for new physics and dark matter. For the first time, we exploit sub-PeV (10 TeV -- 1 PeV) observations of Galactic diffuse gamma rays by Tibet AS$\gamma$ and HAWC to search for an axion-like-particle (ALP) induced gamma-ray signal directly linked to the origin of the IceCube extragalactic high-energy neutrino flux. Indeed, the production of high-energy neutrinos in extra-galactic sources implies the concomitant production of gamma rays at comparable energies. Within the magnetic field of the neutrino emitting sources, gamma rays may efficiently convert into ALPs and escape their host galaxy unattenuated, propagate through intergalactic space, and re-convert into gamma rays in the magnetic field of the Milky Way. Such a scenario creates an all-sky diffuse high-energy gamma-ray signal in the sub-PeV range. Accounting for the guaranteed Galactic astrophysical gamma-ray contributions from cosmic-ray interactions with gas and radiation as well as from sub-threshold sources, we set competitive upper limits on the photon-ALP coupling constant $g_{a\gamma\gamma}$. We find $g_{a\gamma\gamma} < 2.3\times10^{-11}$ GeV$^{-1}$ for ALP masses $m_a \leq 2\times10^{-7}$ eV at a 95\% confidence level, progressively closing the mass gap towards ADMX limits.
Future cosmological probes promise significant progress in probing the dark universe and the related fundamental particles. Their impact is most powerful when we combine cosmological data with astrophysical observations and laboratory experiments. While computational tools are available for such studies, the large number of model parameters and ensuring consistency between data sets can present difficult challenges.
In this talk, I will show how the global-fitting framework GAMBIT can be used to constrain non-thermal axion-like particles (ALPs) with keV-to-MeV masses that decay into photons. For the first time we combine various cosmological and astrophysical constraints in a joint likelihood approach. This ensures the consistency of assumptions and allows us to investigate the entire multi-dimensional parameter space instead of fixing some parameters to benchmark values.
Leaving the ALP abundance and reheating temperature as free parameters, we identify and re-open still viable ALP parameter space -- even slightly improving BBN observables compared to standard cosmology. In this context, I will comment on the additional constraining power from future spectral distortion missions. Our findings demonstrate the important complementarity of astrophysical and cosmological data and encourage the extension of our analysis to models with ALP-matter couplings.
Although the presence of oscillations in fuzzy dark matter (FDM) cores has been noted previously [1-3], e.g. effects of core oscillations on the structure and dynamics of galaxies [2,3], and limits on the constituent boson mass [1], some open questions remain.
Here, we investigate the dynamics and properties of FDM core oscillations both in the absence and presence of self-interactions. We perform an exact analytical study of the oscillation frequency of perturbed ground-state non-interacting soliton cores, inspired by the approach taken in [4], and compare with numerical Gross-Pitaevskii-Poisson simulations. Instead of a Gaussian ansatz, we make use of the empirical fitting formula from [5] to analytically solve for the oscillation frequencies. Our numerical and analytical studies find qualitative agreement with results from [4], but with clearly identifiable corrections, with further adjustments made for the presence of self-interaction.
References:
[1] D.J. Marsh and J.C. Niemeyer, Phys. Rev. Lett., 123, 051103 (2019)
[2] B. V. Church, P. Mocz, and J. P. Ostriker, Mon. Not. R. Astron. Soc. ** 485, 2861 (2019)
[3] X. Li, L. Hui, and T. D. Yavetz, Phys. Rev. D. 103, 023508 (2019)
[4] P.-H. Chavanis, Phys. Rev. D - Part. Fields, Gravit. Cosmol. 84, 1 (2011)
[5] H. Y. Schive, T. Chiueh, and T. Broadhurst, Nat. Phys. 10**, 496 (2014)
Pulsars dominate the local cosmic-ray positron flux at high energies by producing electron-positron pairs from their spindown energy. While the AMS-02 experiment, that measures the cosmic-ray flux to great precision, shows that the positron flux is very smooth, simple simulations of pulsar models predict sharp spectral features. In this work, we add several mechanisms to model the local positron flux more realistically. Specifically, we implement a more realistic positron production mechanism of the pulsars, and take into account various effects on the energy losses of the positrons as they propagate through the Galaxy. Our models show that the sharp spectral features predicted by the simple models vanish, which is consistent with the observed smoothness of the local cosmic-ray positron flux. This re-opens the possibility that sharp spectral features in the cosmic-ray positron flux could provide strong evidence of dark matter annihilation.
Annihilation or decay of dark matter (DM) could contribute to the electron and positron cosmic-ray flux, thus the parameter space of DM candidate models can be probed by these messengers. The signature's location in energy is closely correlated with the DM mass, making the TeV-range of these spectra most important for studying heavy DM of models beyond the WIMP paradigm.
Among the ISS-based experiments, CALET (Calorimetric Electron Telescope) is directly measuring the energy spectrum of electron+positron cosmic rays up to 20 TeV, while the magnet spectrometer AMS-02 can also provide an exclusive positron-only spectrum below the TeV range. The combined analysis of both datasets allows for a sophisticated modeling of the astrophysical background to the DM signature, including pulsars as the origin of the positron excess and individual supernova remnant sources.
For generic annihilation/decay channels, as well as for meson-lepton channels as a possible signature of topological defects, limits ranging from GeV well into the TeV mass range have been calculated based on the latest available data from CALET and AMS-02. In addition to these resulting limits, the limit calculation method and the underlying models of cosmic-ray propagation and astrophysical background are presented.
A fundamental question regarding the Fermi Galactic Center Excess (GCE) is whether the underlying structure is point-like or smooth. This debate, often framed in terms of a millisecond pulsar or annihilating dark matter (DM) origin for the emission, awaits a conclusive resolution. We weigh in on the problem using graph-convolutional neural networks and estimate the fluxes of different emission components as well as the source-count distributions (SCDs) of the underlying point-source populations. We find a faint GCE described by a median SCD peaked at a flux of ∼ 4 × 10e−11 counts / cm^2 / s, which would require N ∼ O(10,000) sources to explain the entire excess (median value N = 29,300 across the sky). Although faint, this SCD allows us to derive the constraint ηP ≤ 66% for the dark matter-like Poissonian fraction of the GCE flux ηP at 95% confidence, suggesting that a substantial amount of the GCE flux is due to point-sources.
The General Anti Particle Spectrometer (GAPS) is a balloon-borne cosmic-ray experiment
currently under construction and scheduled for a long duration balloon flight from McMurdo
Station in the Antarctic.
Its primary science goal is the search for light antinuclei in cosmic rays at kinetic energies in
below 0.25 GeV/n. This energy region is especially of interest for beyond-the-standard model
searches and is still mostly uncharted. Searches for light antimatter nucleons with energies
below ~0.25 GeV/n promise a novel approach for the search of dark matter. A large fraction of
dark matter models proposes annihilation or decay of the unknown dark matter particle with
matter/antimatter pairs in its final state. Someantiparticle searches carried out so far hit for a
possible excesss of antiparticles at low energies, however, the large uncertainties in the
astrophysical backgrounds make interpretations challenging.
GAPS promises to yield unprecedented sensitivity for the search of antideuterons and will
measure the low-energy antiproton spectrum with large statistics and high precision. To reach
the required sensitivity, the GAPS detector incorporates a new approach for antimatter
detection, utilizing a tracker with custom-designed, lithium-drifted silicon detectors, designed
to measure the X-ray cascade expected from antimatter capture, together with fast time-of-
flight system, allowing for a high precision beta measurement.
This talk will review the current progress of construction and the overall status of the
instrument, discuss the latest sensitivity estimates and present the path forward to the first
flight.
GRAMS (Gamma-Ray and AntiMatter Survey) is a next-generation proposed balloon/satellite mission that will be the first to target both MeV gamma-ray observations and antimatter measurements with a LArTPC (Liquid Argon Time Projection Chamber) detector. With a cost-effective, large-scale LArTPC, GRAMS can have extensively improved sensitivities to both MeV gamma rays and antiparticles compared with previous missions. MeV gamma-ray measurements with GRAMS can explore new parameter space for annihilating dark matter and evaporating primordial black holes. GRAMS is also capable of exploring dark matter parameter space via antimatter measurements. In particular, low-energy antideuterons and antiheliums measurements can offer background-free dark matter searches. We are currently building a prototype detector, MiniGRAMS, to validate the detection concept. In this talk, I will give an overview and the current status of the GRAMS project.
MadDM is an automated numerical tool for the computation of dark-matter observables for generic new physics models based on the Monte Carlo generator MadGraph5_aMC@NLO. Notably, the code provides a comprehensive framework for the reinterpretation of direct and indirect detection searches. For instance, it allows the user to compute the fully differential nuclear recoil rates as well as the energy spectra of photons, neutrinos and charged cosmic rays for arbitrary 2 to n annihilation processes. We report on MadDM v3.2 enabling the automatized computation of loop-induced annihilation processes as well as ongoing developments of its capabilities for direct detection. We showcase their physics applications.
Extensions of the Two Higgs Doublet model with a complex scalar singlet (2HDMS) can accommodate all current experimental constraints and are highly motivated candidates for Beyond Standard Model Physics. It can successfully provide a dark matter candidate as well as explain baryogenesis and provides gravitational wave signals. In this work, we focus on the dark matter phenomenology of the 2HDMS with the complex scalar singlet as the dark matter candidate. We study variations of dark matter observables with respect to the model parameters and present representative benchmark points in the light and heavy dark matter mass regions allowed by existing experimental constraints from dark matter, flavour physics and collider searches. We also compare real and complex scalar dark matter in the context of 2HDMS. Further, we discuss the discovery potential of such scenarios at future colliders.
Belle has unique reach for a broad class of models that postulate the existence of dark matter particles with MeV—GeV masses. This talk presents recent world-leading physics results from Belle II searches for dark Higgstrahlung and invisible Z′ decays; as well as the near-term prospects for other dark-sector searches.
The CDF collaboration recently reported a new precise measurement of the W boson mass MW with a central value significantly larger than the SM prediction. We explore the effects of including this new measurement on a fit of the Standard Model (SM) to electroweak precision data. We characterize the tension of this new measurement with the SM and explore potential beyond the SM phenomena within the electroweak sector in terms of the oblique parameters S, T, and U. We show that the large $M_W$ value can be accommodated in the fit by a large, nonzero value of U which is difficult to construct in explicit models. Assuming $U=0$ the electroweak fit strongly prefers large, positive values of T. Finally, we study how the preferred values of the oblique parameters may be generated in the context of models affecting the electroweak sector at tree- and loop-level. In particular, we demonstrate that the preferred values of S and T an be generated with a real $SU(2)_L$ triplet scalar, the humble "swino," which can be heavy enough to evade current collider constraints, or by (multiple) species of a singlet-doublet fermion pair. We highlight challenges in constructing other simple models, such as a dark photon, for explaining a large $M_W$ value, and several directions for further study.
SND@LHC is a compact and stand-alone experiment to perform measurements with neutrinos produced at the LHC in a hitherto unexplored pseudo-rapidity region of 7.2 < 𝜂 < 8.6, complementary to all the other experiments at the LHC. The experiment is to be located 480 m downstream of IP1 in the unused TI18 tunnel. The detector is composed of a hybrid system based on an 800 kg target mass of tungsten plates, interleaved with emulsion and electronic trackers, followed downstream by a calorimeter and a muon system. The configuration allows efficiently distinguishing between all three neutrino flavours, opening a unique opportunity to probe physics of heavy flavour production at the LHC in the region that is not accessible to ATLAS, CMS and LHCb. This region is of particular interest also for future circular colliders and for predictions of very high-energy atmospheric neutrinos. The detector concept is also well suited to searching for Feebly Interacting Particles via signatures of scattering in the detector target. The first phase aims at operating the detector throughout LHC Run 3 to collect a total of 150 fb−1. The experiment was recently approved by the Research Board at CERN. A new era of collider neutrino physics is just starting.
The search for dark matter signals is nowadays an important asset of many particle physics experiments at accelerators.
This approach to the dark matter study, the most abundant constituent of the universe, has contributed in setting more stringent limits on the characteristics of dark matter.
The Positron Annihilation into Dark Matter Experiment (PADME) [1] searches for a signal of a dark photon A’ [2] in the $e^+ e^-\rightarrow A'\gamma$ reaction in a positron-on-target experiment. For this purpose, it is analyzed the missing mass spectrum of final states with a single photon, produced in the annihilation of the positron beam of the DA\PhiNE Beam-Test Facility, at Laboratori Nazionali di Frascati of INFN, on the electrons of a thin diamond target.
The PADME approach allows to look for any new particle produced in $e^+ e^-$ collisions through a virtual off-shell photon such as long lived Axion-Like-Particles (ALPs), proto-phobic X bosons, Dark Higgs.
In the talk, the scientific program of the experiment and the first physics results will be illustrated. In particular, the detector performance evaluated studying the cross-section of the SM process $e^+ e^- \rightarrow \gamma\gamma$ at $\sqrt{s}$=21 MeV will be shown.
Dinner starts at 19:30
I show that the dark Higgs Boson, which is often ignored in DM phenomenology, can play a crucial and important role by restoring unitarity and opening new channels for DM pair annihilation. These are demonstrated in a number of different examples: (i) the invisible Higgs decay width in vector DM with Higgs portal,(ii) scalar or fermion inelastic DM and the exothermic DM scattering for the Xenon1T excess,(iii) collider searches for the s-channel scalar mediators, and (iv) Higgs-portal assisted Higgs inflation.
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With a 5.9 tonne liquid xenon target, XENONnT is the latest of the XENON direct detection experiments searching for dark matter. Currently, the detector is taking data at the INFN Laboratori Nazionali del Gran Sasso. XENONnT has achieved unprecedented purity both for electronegative contaminants, with an electron lifetime exceeding $10~\mathrm{ms}$, and for radioactive ${}^{222}$Rn, with an activity of $1.72\pm0.03~\mu$Bq/kg. This talk will give an overview of the XENONnT experiment, the calibration and performance of the detector and projections of its performance.
Deep Underground Laboratories are large research infrastructures with a rock overburden of order one km water equivalent.
In DULs the flux of muons from cosmic rays is reduced by several orders of magnitude with respect to surface. This allows to search for very rare events,
such as exotic radioactive decays, double beta decays, low energy neutrino and dark matter interactions.
The phenomenon of neutrino oscillations has been discovered in DULs back in 1998. Solar neutrinos were first observed in a DULs in 1968.
In 1987 neutrinos from a core collapse supernova in the Large Magellanic Cloud were observed in DULs, confirming our basic understanding of this high energetic event.
At present, DULs are equipped with more sensitive and better performing experiments to improve significantly these early studies.
In the last decade the research horizon in DULs has expanded to include gravitational waves, geophysics, and biology in underground environments.
DULs are equipped with unique facilities to support research by means of different techniques.
DULs are being used by a large community of scientists ranging from astrophysics, particle physics, geophysics, and biology.
There are 14 underground locations worldwide which can be classified as DULs.
In the talk a brief review of DULs main features and research activities will be discussed with emphasis to rare events search, in particular to dark matter direct detection.
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