UCLA Dark Matter 2023

29 Mar 2023, 07:15 → 1 Apr 2023, 15:00 US/Pacific

PAB- 1-425 (UCLA)

For information on the venue and accommodations,  use the "UCLA Conference Website" link to the left or go to https://conferences.pa.ucla.edu/dark-matter-2023

For registration, please click on the "Registration" option on the left of this Indico page. After you register on this website, to pay for the registration and/or additional banquet tickets, please use the "Registration-Payment" link to the left or  https://commerce.cashnet.com/DARKMATTER 

Please note that the early registration fee $(\$600)$ will change on February 7th, 2023, at 16:00 (4pm) Pacific Time into our regular registration fee $(\$650)$ until March 8th at the same time. After which, the late registration fee $(\$700)$ will be charged. Notice that the early registration period has  been extended  by one week.  We encourage participants to register as early as possible to facilitate our planning.

 

Please note that the conference attendees will be subject to the UCLA COVID-19 protocols that will be valid at the time of the conference.

Wednesday, 29 March

Morning Coffee

Welcome

1 Welcome from our Department Chair

Speaker: Stuart Brown (UCLA)

2 Announcements

Speaker: Graciela Beatriz Gelmini (University of California Los Angeles (US))

Announcements.pdf

SESSION 1: Cosmology and structure formation (CHAIR: Graciela Gelmini- UCLA)

3 Cosmic Anomalies?

Cosmology has advanced from "2.5 facts" in 1963 to a very data-rich field today. This has led to the determination of the baryon density, the dark matter density, and the dark energy density. But more facts lead to a greater reliance on advanced statistical techniques, which are usually useful but occasionally misleading. It is important to consider "look elsewhere effects", and to remember that even the true model will not fit all the data.

Speaker: Edward Wright (UCLA)

Wright-UCLA-DM-230329.pdf

Wright-UCLA-DM-230329.pptx

4 Dark Energy

Speaker: Josh Frieman (Fermilab)

DarkEnergy-UCLA (1).pdf

DarkEnergy-UCLA (2).pdf

DarkEnergy-UCLA (2).pptx

5 Structure Formation in the Universe

In its most basic form, the highly successful $\Lambda$CDM cosmology can be encapsulated in six parameters. Once these parameters are specified, so too is a wide variety of phenomena, from fluctuations in the microwave background to the growth of structure to the evolution of the expansion rate of the Universe. I will review the predictions related to cosmological structure formation, focusing on areas where potential tensions have emerged: these include nonlinear scales at the earliest times and smallest mass scales and comparisons between measurements early and late in the Universe's history.

Speaker: Mike Boylan-Kolchin

UCLA_2023_mbk.key

UCLA_2023_mbk.pdf

6 Dark Matter Searches with Strong Gravitational Lensing

Speaker: Dr Anna Nierenberg

Nierenberg_ UCLA_DM_2023.pdf

Nierenberg_ UCLA_DM_2023.pptx

10:00 Coffe Break

SESSION 2: Astrophysics and Indirect Dark Matter Searches (CHAIR: Ned Wright- UCLA)

Convener: Jo Bovy

7 Dark Matter and Tidal Streams

Speaker: Jo Bovy

bovy_ucla_dm.key

bovy_ucla_dm.pdf

8 Indirect Dark Matter Detection

Speaker: Tracy Slatyer

UCLA_DM_Indirect_Detection_Slatyer.pdf

9 Dark Matter Searches with Neutrino Telescopes

Speaker: FRANCIS HALZEN

UCLA2023_Halzen.pdf

10 Search for Dark Matter with IACTs and CTA

Search for Dark Matter with Imaging Atmospheric Cherenkov Telescopes and the Cherenkov Telescope Array

The annihilation or decay of dark matter particles may lead to the production of gamma rays. For dark matter particles with masses above ~100 GeV, these final state gamma rays can be detected by ground-based imaging atmospheric Cherenkov telescope arrays. By observing dark-matter-rich astrophysical targets, the current generation instruments H.E.S.S., MAGIC and VERITAS search for signals of dark matter annihilation or decay. These instruments have collected deep exposures on dark matter targets and set constraints on the velocity-weighted cross section for dark matter self-annihilation, as well as limits on the lifetime of a decaying dark matter particle. The next generation instrument, the Cherenkov Telescope Array, will have an order of magnitude better flux sensitivity than the current generation instruments, allowing it to probe below the thermal relic cross section over a broad dark matter mass range.

Speaker: Elisa Pueschel

UCLADM_Pueschel.pdf

12:30 Lunch Break

SESSION 3: Dark Matter Particle Candidates and Accelerator Searches (CHAIR: Tracy Slatyer - MIT)

11 Dark Matter Particle Candidates

Speaker: Kathryn Zurek (Caltech)

23_UCLA_DM_Zurek_red.pdf

12 Axions and Axion-Like Particles Dark Matter

Speaker: Surjeet Rajendran

Rajendran UCLA.pdf

13 Sterile Neutrino Dark Matter

Speaker: George Fuller (UCSD)

DarkMatter23.ppt

14 Primordial Black Holes as Dark Matter

Primordial black holes from the early Universe constitute an attractive non-particle dark matter candidate. I will review their current status and outline prospects for discovery.

Speaker: Volodymyr Takhistov

UCLADM2023_Takhistov.pdf

15 Dark Matter Searches at Accelerators

Dark Matter and dark sectors are the target of an increasingly large number of experiments at accelerators and colliders. I will review some of the candidates being targeted, current experiments and new results, and exciting ideas that are being proposed for the future.

Speaker: Jonathan Lee Feng (University of California Irvine (US))

2303ucladm.pdf

16:00 Coffee Break

SESSION 4: Direct Dark Matter Detection (CHAIR: Jonathan Feng- UCI)

16 Direct Detection with Xenon

Speaker: Elena Aprile (Columbia U.)

UCLA_Aprile_directdetection.pdf

17 Direct Detection with Argon

Speaker: Cristiano Galbiati (Princeton University)

UCLA DM 2023 Mar 29 2023.pdf

18 Direct Detection Without Noble Gases

Speaker: Priscilla Cushman

UCLA_DM23_Cushman.pdf

UCLA_DM23_Cushman.pptx

19 New Ideas for Sub-GeV Dark Matter Direct Detection

Speaker: Rouven Essig (Stony Brook University)

Rouven-Essig-UCLA-DM.final.pdf

Reception and Poster Session in the same room

20 Detection of dark matter-baryon matter non-gravitational interaction

Does the non-baryon 95% of the universe possess specific physical characteristics that can be compared to those of a gas or a fluid, and can it interact with ordinary matter in a direct way other than gravitational interaction? By using the Lorentz factor in Stokes' law as the apparent-viscosity coefficient of space, which is treated as a dark fluid with non-Newtonian and dilatant characteristics, it is shown that some well-known anomalies are resolved with precision, directly obtaining for instance both the exact value of the Pioneer anomaly (without resorting to simulations, as in the hitherto accepted solution, which has a large margin of error and is based on various uncertain data) and that of the precession of Mercury's perihelion, by deriving Einstein equation in a new way, based on space as a dark dilatant fluid. This specific type of dark fluid that emerges is also capable of explaining the spider-web structure of dark matter filaments in the universe and predicts their rotation.

Speaker: Marco Fedi (Ministero dell'Istruzione, Italy)

Describing space as oobleck solves decades-old physics mystery (J.Kliever)

poster_Fedi_UCLA-DarkMatter2023_120dpi.pdf

21 Developing Qubit-based Detectors for Low-threshold Dark Matter Searches in the LOUD Facility at Fermilab

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 in common superconductors (~meV). Quantum sensors that are sensitive to these broken Cooper pairs can potentially be exploited as low-threshold detectors for particle-like DM scattering. The Quantum Science Center group at Fermilab is currently exploring the possibility of employing superconducting qubits in this capacity, and has developed LOUD, a fast-turnaround cryogenic test platform for qubit performance testing. A separate effort to simulate the effect of charge and phonon propagation in qubit substrates to understand impacts on qubit coherence times is also underway. Together, these complementary efforts are intended to inform iterations on device design to push detection thresholds into the sub-eV regime. This poster will discuss recent progress of the LOUD facility as well as elements of simulation that enable mapping of particle impacts to qubit performance.

Speaker: Ryan Linehan

22 Toward a Dark Matter Search with Phonon-Mediated MKID Devices at NEXUS

To continue the search for dark matter (DM) into the sub-GeV mass range, the development and characterization of new detectors with sub-eV thresholds is critical. Microwave Kinetic Inductance Detectors (MKIDs) offer an attractive architecture for novel microcalorimeters with the requisite energy resolution and threshold for probing DM down to the fermionic thermal relic mass limit of a few keV. A phonon-sensitive MKID device featuring an aluminum resonator patterned onto a silicon substrate has been operating at the NEXUS low-background facility at Fermilab for characterization and evaluation of its efficacy for a dark matter search. Currently, our estimate of the energy resolution of this device is limited by the efficiency for phonons produced via particle interactions in the substrate to propagate to the superconductor and break Cooper pairs. In this poster, I will present our constraints on the substrate-superconductor coupling and the progress on an absolute energy calibration performed by exposing the rear of the substrate to a pulsed source of 470 nm photons. I will also review the current status and next steps of the phonon-mediated MKID effort at Fermilab.

Speaker: Dylan Temples (Fermilab)

23 Amplified J-factors in the Galactic Center for velocity-dependent darkmatter annihilation in FIRE simulations

We use FIRE-2 zoom cosmological simulations of Milky Way size galaxy halos to calculate astrophysical J-factors for dark matter annihilation and indirect detection studies. In addition to velocity-independent (s-wave) annihilation cross sections σv, we also calculate effective J-factors for velocity-dependent models, where the annihilation cross section is either either p-wave (∝v2/c2) or d-wave (∝v4/c4). We use 12 pairs of simulations, each run with dark-matter-only (DMO) physics and FIRE-2 physics. We observe FIRE runs produce central dark matter velocity dispersions that are systematically larger than in DMO runs by factors of ∼2.5−4. They also have a larger range of central (∼400 pc) dark matter densities than the DMO runs (ρFIRE/ρDMO≃0.5−3) owing to the competing effects of baryonic contraction and feedback. At 3 degrees from the Galactic Center, FIRE J-factors are 5−50 (p-wave) and 15−500 (d-wave) times higher than in the DMO runs. The change in s-wave signal at 3 degrees is more modest and can be higher or lower (∼0.3−6), though the shape of the emission profile is flatter (less peaked towards the Galactic Center) and more circular on the sky in FIRE runs. Our results for s-wave are broadly consistent with the range of assumptions in most indirect detection studies. We observe p-wave J-factors that are significantly enhanced compared to most past estimates. We find that thermal models with p-wave annihilation may be within range of detection in the near future.

Speaker: Daniel Mckeown (University of California-Irvine)

24 Interpretation of modulating amplitude and phase from the DAMA/LIBRA analysis method

The COSINE-100 collaboration recently released a study suggesting possible cause of the annual modulation from an analysis method adopted by the DAMA/LIBRA experiment in which the observed modulating signal could be attributed to a slowly varying time-dependent background. The DAMA/LIBRA collaboration's claim for a dark matter signal has been debated over the last two decades. However, despite many collaborations' attempts to reproduce DAMA's results, no definitive evidence has been observed. COSINE-100's model-independent, annual modulation search adopting the analysis procedure as close as possible to the DAMA/LIBRA method with COSINE-100 data finds a strong modulation, but with opposite phase. Here, I will summarize the results of this study and possible scenarios that suggest causes for DAMA's signal phase.

Speaker: Sophia Hollick (Ya)

UCLAciodposter.pdf

25 Primordial Black Hole and Gravitational Wave Production from ALP String-Wall Networks

Recent advances in gravitational wave detection have opened new doors for probing the physics of the early universe, raising the possibility of finding gravitational-wave evidence for the existence of dark matter candidates that have not yet been detected by other methods. In particular, this possibility has motivated the exploration of topological defect formation and decay associated with the existence of scalar fields. We investigate a cosmology that includes a scalar field with a spontaneously broken U(1) symmetry that is also explicitly broken at a lower energy scale, leading to the formation of domain walls that then both annihilate into axion-like particles and could collapse into black holes. In this model, both the axion-like particles and the primordial black holes are viable dark matter candidates. We show the mass ranges where this model could both account for all (or part of) the dark matter and produce gravitational waves observable in the near future.

Speakers: ANNA SIMPSON (UCLA), Jonah Hyman (UCLA)

DM Conference Poster-rev2.pdf

26 Halo-independent analysis of direct DM detection through electron scattering

Sub-GeV DM particles could be revealed through their Scattering with electrons. The analysis of data from direct detection experiments usually requires assuming a local DM halo velocity distribution; however, in the halo-independent analysis method, properties of velocity distribution are instead inferred from the data, which allows comparing different data sets without making any assumption on the uncertain halo characteristics. This method has been applied to DM nuclei scattering, and here we demonstrate how this analysis can be applied to DM electron scattering.

Speaker: Muping Chen

Muping Chen poster UCLA DM 2023.pdf

27 Calibrating the DMRadio-50L Detector

Dark Matter Radio 50L (DMRadio-50L) is a resonant, lumped-element detector searching for low-mass axion dark matter. The detector will have a toroidal superconducting magnet enclosed by a superconducting sheath connected to a high-Q tunable LC resonator. In this talk, I will outline the calibration plan the experiment will employ to determine its end-to-end sensitivity. A variety of methods will be used, including a mimetic axion signal injected into the detector, resonator noise measurements, multichannel SQUID chain calibration, and sideband injection. These results will allow us to characterize the detector and convert raw detector data into limits on $g_{a\gamma\gamma}$.

Speaker: Jessica Fry (Massachusetts Institute of Technology)

28 Searching for Dark Matter From The Sun With Ten Years of IceCube Data

The existence of dark matter (DM) has been well-established by repeated experiments probing various length scales. Even though DM is expected to make up 85% of the current matter content of the Universe, its nature remains unknown. One broad class of corpuscular DM motivated by Standard Model (SM) extensions is weakly interacting massive particles (WIMPs). WIMPs can generically have a non-zero cross-section with SM nuclei, which allows them to scatter off nuclei in large celestial bodies such as the Sun, losing energy and becoming gravitationally bound in the process. After repeated scattering, WIMPs sink to the solar center, leading to an excess of WIMPs there. Subsequently, WIMPs can annihilate to stable SM particles, either directly or through a decay chain of unstable SM particles. Among stable SM particles, only neutrinos can escape the dense solar core. Thus, one may look for an excess of neutrinos from the Sun's direction as evidence of WIMPs. The IceCube Neutrino Observatory, which detects Cherenkov radiation of charged particles produced in neutrino interactions, is especially well-suited to such searches since it is sensitive to WIMPs with masses in the region preferred by supersymmetric extensions of the SM. In this contribution, I will present the results of IceCube's most recent solar WIMP search, which includes all neutrino flavors, covers the WIMP mass range from 10 GeV to 1 TeV, and has world-leading sensitivity over this entire range for most channels considered.

Speaker: Jeffrey Lazar (University of Wisconsin-Madison)

29 Xenoscope — a full-scale vertical demonstrator for the DARWIN observatory

The DARWIN observatory is a proposed next-generation experiment to search for particle dark matter and other rare interactions. It will operate a 50 t liquid xenon detector, with 40 t in the time projection chamber (TPC). To inform the final detector design and technical choices, a series of technological questions must first be addressed. I will describe a full-scale demonstrator in the vertical dimension, Xenoscope, which was constructed at the University of Zurich. The main goal is to achieve electron drift over a 2.6 m distance, which is the scale of the DARWIN TPC. Other applications of the facility include R&D on the high voltage feedthrough, measurements of electron cloud diffusion, as well as measurements of optical properties of liquid xenon. Xenoscope is also available as a test platform for the DARWIN collaboration to characterise new detector technologies.

Speaker: Laura Baudis

Baudis_Xenoscope_poster_UCLADM_2023.pdf

30 Exploration of Wire-Array Metamaterials for the Plasma Axion Haloscope

Authors:
Rustam Balafendiev, Pavel Belov, Alex Droster, Maxim Gorlach, Nolan Kowitt, Samantha Lewis, Dajie Sun, Mackenzie Wooten, Karl van Bibber

Recent theoretical work predicts the mass of the post-inflation axion to lie above 40𝜇eV (~10 GHz) [1], higher than where microwave cavity experiments can effectively reach, owing to the steeply decreasing volume of the cavity with frequency. It has recently been proposed to circumvent this limitation by replacing the microwave cavity with a wire-array metamaterial whose plasma frequency is determined by its unit cell rather than its boundary conditions, i.e. its size, as is the case with conventional microwave cavities [2]. Thus in principle it is possible to build a resonator that could be both arbitrarily high in frequency and arbitrarily large. We have performed initial investigations of the feasibility of this concept by microwave transmission measurements (𝑆21 scattering parameter), data from which we extract the plasma frequency, loss term and effective width; based on these results we can project quality factors 𝑄 > 10,000 for a resonator at cryogenic temperatures [3]. More recently we have carried out a study of the plasma frequency as a function of unit cell parameters demonstrating a dynamic range in frequency usable in an axion haloscope.

This work supported under NSF Grants No. PHY-1914199 and PHY-2209556.

1- M. Buschmann et al., Nature Communications 18, 1049 (2022).
2- M. Lawson, et al., Physical Review Letters 123, 141802 (2019).
3- M. Wooten, et al., Annalen der Physik (accepted for publication, 2023), arXiv:2203.13945v3

Speaker: Nolan Kowitt (University of California Berkeley)

DM23_Poster_Kowitt.pdf

31 A mobile neutron spectrometer for the LNGS underground laboratory

Environmental neutrons are a source of background for various rare event searches (e.g., dark matter direct detection and neutrinoless double beta decay experiments) taking place in deep underground laboratories. The overwhelming majority of these neutrons are produced in the cavern walls by means of intrinsic radioactivity of the rock and concrete. Their flux and spectrum depend on location. Precise knowledge of this background is necessary to devise shielding and veto mechanisms, improving the sensitivity of the neutron-susceptible underground experiments.
Ambient neutrons have been measured previously at different locations of the underground laboratory LNGS in Italy. However, flux numbers vary considerably across the measurements and direct comparison between them is difficult owing to the use of different detector technologies and setups, each of which possesses characteristic systematics and energy windows. A project was launched to solve these issues and enhance the scientific infrastructure of LNGS.
We present the design and the expected performance of a portable neutron detector based on capture-gated spectroscopy as well as first test measurements and give an outlook towards the deployment at LNGS. This project is funded by the German Federal Ministry of Education and Research (BMBF) under the grant number 05A21VK1.

Speaker: Melih Solmaz

MelihSolmaz_UCLA_DM_2023_Poster_v2.pdf

32 Towards Quantum Charge Parity Detectors with meV Resolution for sub-GeV Dark Matter Detection

The increasingly theoretically relevant "sub-GeV" mass particle dark matter landscape requires new tools and techniques to fully investigate. In particular, the constrained kinematic space of potential interactions suggests that collective excitations like phonons may be the only signature of very low mass dark matter candidates. One promising technology to study these are qubit derived superconducting charge-parity sensors. These detection schemes include Quantum Capacitance Detectors (QCDs) and Offset-Charge Sensitive (OCS) devices, and the former have been demonstrated in previous literature as excellent far-IR photon counters with NEP of <10−20 W/Hz‾‾‾√. We seek to extend the applicability of these techniques by directly coupling the sensors to interaction induced athermal phonons generated within a crystalline silicon substrate. Such a scheme will enable the literal counting of O(100) ueV quasiparticle quanta (broken Cooper-pair electrons) within a superconducting absorber, as produced by single meV phonons. In this presentation, we will discuss progress towards demonstrating a charge-parity detector design, and lay out a roadmap for demonstrating eV and subsequently lower energy resolution in future iterations.

Speaker: Karthik Ramanathan

33 Backgrounds from Frenkel defects in direct detection experiments

A promising strategy for direct detection of sub-MeV dark matter is to look for phonon excitations in crystals. The crystal targets used in such experiments are typically not completely pure, and have impurities or defects. Frenkel defect is an example of a point defect where an atom is dislodged from its position and occupies an interstitial position leaving behind a vacancy. These defects can diffuse and recombine to emit energy in the form of phonons, and can potentially create a background for direct detection experiments. We estimate the defect densities produced through thermal excitations as well as radiogenic nuclear recoils. For various defect configurations, we quantify the diffusion and recombination rates for both thermal and quantum tunneling mechanisms. We find that the thermally generated defects are effectively frozen at cryogenic temperatures and cannot diffuse to recombine with each other. The radiogenic defects produced on the surface can be annealed effectively at room temperature for typical defect configurations, but defects produced through radiogenic nuclear recoils in a shielded environment at cryogenic temperatures during the run-time of the experiment can recombine to produce eV-scale events. We estimate this recombination rate for different defect configurations.

Speaker: Mukul Sholapurkar

34 Calibrating the Migdal Effect in Semiconductors

The Migdal Effect has seen a surge of interest in recent years, and has been leveraged to set what are in fact the strongest limits on nuclear recoils of dark matter below masses of a few GeV. While the existence of the Migdal Effect only relies on fairly basic quantum mechanics, the matrix elements involved have never been directly calibrated. I lay out the importance of measuring the Migdal effect through low-energy nuclear recoil calibrations, what sort of signal to expect in such a neutron calibration experiment with a semiconductor target, and propose one such experimental setup that could be capable of performing this calibration using the NEXUS facility at Fermilab.

Speaker: Daniel Baxter (Fermi National Accelerator Laboratory)

UCLA_MigdalPoster.pdf

35 Low energy calibration and characterization of solid-state dark matter detectors

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 system capable of cryogenic optical beam steering for robust calibration of any photon-sensitive detector over the energy range of 0.06 - 5eV. This system can be used to scan over a detector and deliver short, 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 on detector operation. I will present the design overview and specifications, along with current status of the testing program involving mKID and qubit devices.

Speaker: Kelly Stifter (Fermilab)

Stifter_QuantumCalibration_UCLADM2023.pdf

36 Status for COSINE-100 Upgrade and COSINE-200

The COSINE-100 experiment searches for weakly interacting massive particles with 106 kg of NaI(Tl) crystals in Yangyang, Korea. The effort will eventually progress toward the COSINE-200 detector with 200 kg of new crystals. Until the arrival of the required crystals, we organize a staged detector called the COSINE-100 Upgrade. The Upgrade will consist of a refurbishment of the existing crystals with improved encapsulation and run at -30 deg. C, which would show 30-40% higher light yields. The construction for the COSINE-100 Upgrade is ongoing in the newly built Yemilab and is scheduled to finish this summer. The status of the Upgrade and preparation for COSINE-200 will be presented.

Speaker: Kim Jinyoung

UCLA 포스터 최종.pdf

37 A signal search for the dark axion portal in the NEON experiment

Neutrino Elastic scattering Observation with NaI (NEON) is in progress at the Hanbit nuclear power plant in Yeonggwang, South Korea. The NEON experiment consists of 15 kg of target crystals immersed in 700 liters of scintillating liquid, and located at 24 meters from the 2.8 GW reactor core. The main goal of NEON is to observe the reactor electron anti-neutrino coherent scattering (CEvNS) using NaI(Tl) crystal detectors. NEON's CEvNS observation requires a very low energy threshold of less than 0.5 keV with a precise understanding of the detector and surrounding environment. While accumulating sufficient data and developing an optimal analysis for the CEvNS measurement, we perform a search for dark axion portal (DAP) signals where an axion couples with a dark photon and an electron with a relatively higher threshold. Being exposed to a high flux in a large amount of liquid scintillator, the detector is poised to be highly sensitive to the DAP signals. In this poster, an overview of the NEON experiment and an analysis strategy for DAP are introduced.

Speaker: Byoung-cheol KOH

UCLA_DarkMatter2023_poster.pdf

38 Experimental tests for the fundamental properties of the electron with COSINE-100

The electron decay and its Pauli exclusion principle (PEP), being the basis of the quantum mechanics, have not been proved experimentally. Using the energy spectra of NaI(Tl) crystals in COSINE-100, the electron stability and the PEP violation process have been searched. We fit for X-ray signals in iodine that are emitted when the K- or L-shell electron decays into three neutrinos for the electron stability. For the PEP violation, we search for X-ray signals when an L-shell electron transitions to the already-filled K-shell. Sensitivities of year for the electron lifetime and year for the PEPV lifetime have been obtained.
The preliminary fits using COSINE-100 data of 38.62 kgyear for the electron lifetime and 44.77 kgyear for the PEP violation will be presented in this poster.

Speaker: Yujin Lee

39 DMRadio-50L Experiment Status and Overview

Axions are a well-motivated dark matter candidate, which currently have a wide open and accessible parameter space, with few constraints on their mass and coupling strength to photons. The DMRadio-50L experiment seeks to explore a wide portion of this axion parameter space (between 5 kHz - 5 MHz), taking advantage of lumped element high-Q resonators with optimal out-of-band sensitivity. DMRadio-50L will utilize a toroidal magnet with a field strength of 1 T with a sensitivity goal of at least $𝑔_{a\gamma\gamma}\sim$5e-15 GeV$^{−1}$ across the entire region of interest. At the same time , it will serve as a test bed for advanced quantum readout technologies. In this talk, we will present an overview of the current status of the DMRadio-50L experiment currently entering the construction phase at Stanford as well as current efforts to optimize the experiment design in order to reach the above science goals.

Speaker: Alexander Friedrich Leder

UCLADarkMatter_Conference_2023_final.pdf

40 DMRadio-m3: An Overview

Targeting the DFSZ model of the axion between 30 and 200 MHz and the KSVZ model down to 10 MHz, DMRadio-m3 will operate a lumped-element LC resonator at unprecedented sensitivities. The m3 experiment uses a 4.6 T superconducting solenoidal magnet design, as opposed to the toroidal design that is intended for the DMRadio-50L search. The m3 detector is comprised of a lumped element LC resonator and low noise receiver chain using dc SQUIDs, requiring vibration mitigation strategies. We present the overview of the DMRadio-m3 experiment and a broad path forward to its commissioning at SLAC.

Speaker: Nicholas M. Rapidis (Stanford University)

m3-Rapidis-poster_v3.pdf

41 Observing gravitational waves at sub-nanohertz frequencies

Gravitational waves with frequencies below 1 nHz are notoriously difficult to detect. With periods exceeding current experimental lifetimes, they induce slow drifts in observables rather than periodic correlations. Observables with well-known intrinsic contributions provide a means to probe this regime. In this talk, I will demonstrate the viability of using observed pulsar timing parameters to discover such ultralow-frequency gravitational waves, presenting two complementary observables for which the systematic shift induced by ultralow-frequency gravitational waves can be extracted. I will then show the results of searches for both continuous and stochastic signals in this regime using existing data for these observables, with a focus on supermassive black holes and phase transitions in the dark sector.

Speaker: William De Rocco

42 Potential for definitive discovery of a 70 GeV dark matter WIMP with only second-order gauge couplings

We discuss the potential for discovery of a recently proposed dark matter WIMP which has a mass of about 70 GeV/c$^2$ and only second-order couplings to W and Z bosons. There is evidence that indirect detection may already have been achieved, since analyses of the gamma rays detected by Fermi-LAT and the antiprotons observed by AMS-02 are consistent with 70 GeV dark matter having our calculated $\langle \sigma_{ann} v \rangle \approx 1.2 \times 10^{-26} $ cm$^3$/s. The estimated sensitivities for LZ and XENONnT indicate that these experiments may achieve direct detection within the next few years, since we estimate the relevant cross-section to be slightly above $10^{-48}$ cm$^2$. Other experiments such as PandaX, SuperCDMS, and especially DARWIN should be able to confirm on a longer time scale. The high-luminosity LHC might achieve collider detection within about 15 years, since we estimate a collider cross-section slightly below 1 femtobarn.
[1] Reagan Thornberry, Maxwell Throm, John Killough, Dylan Blend, Michael Erickson, Brian Sun, Brett Bays, Gabriel Frohaug, and Roland E. Allen, EPL [European Physics Letters] 134, 49001 (2021), arXiv:2104.11715 [hep-ph], and references therein.
[2] Caden LaFontaine, Bailey Tallman, Spencer Ellis, Trevor Croteau, Brandon Torres, Sabrina Hernandez,Diego Cristancho Guerrero, Jessica Jaksik, Drue Lubanski, and Roland E. Allen, Universe 7, 270 (2021), arXiv:2107.14390 [hep-ph].
[3] Bailey Tallman, Alexandra Boone, Caden LaFontaine, Trevor Croteau, Quinn Ballard, Sabrina Hernandez, Spencer Ellis, Adhithya Vijayakumar, Fiona Lopez, Samuel Apata, Jehu Martinez, and Roland Allen, proceedings of the 41st International Conference on High Energy Physics, ICHEP 2022, arXiv:2210.05380 [hep-ph].
[4] Bailey Tallman, Alexandra Boone, Adhithya Vijayakumar, Fiona Lopez, Samuel Apata, Jehu Martinez, and Roland Allen, submitted to Letters in High Energy Physics, arXiv:2210.15019 [hep-ph].

Speaker: Roland Allen

Allen UCLA poster.pdf

43 Searching for Light Dark Matter with Narrow-gap Semiconductors - the SPLENDOR Experiment

The SPLENDOR (Search for Particles of Light Dark Matter with Narrow-gap Semiconductors) experiment is a search for light dark matter via the electron-recoil interaction channel, taking advantage of novel single-crystal narrow-bandgap (order 10-100 meV) semiconductors. Synthesized within the collaboration, the properties of these designer materials imply low dark counts when operated as ionization detectors at cryogenic temperatures. Using a readout scheme based on low-noise cryogenic high electron mobility transistors (HEMTs), the experiment is on track to achieve O(1) electron-hole pair resolution. This provides an excellent opportunity to probe new light dark matter parameter space: down to sub-MeV masses for fermionic dark matter and sub-eV masses for bosonic dark matter. I will review the multidisciplinary R&D behind SPLENDOR, discuss the current status of the experiment, and present projected sensitivities for planned dark matter searches operated both above- and below-ground.

This work was supported by the U.S. Department of Energy through the Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of U.S. Department of Energy (Contract No. 89233218CNA000001). Research presented in this presentation was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project number 20220135DR.

Speaker: Samuel Watkins (Los Alamos National Laboratory)

splendor_poster_ucladm2023.pdf

44 Searches of light dark matter and B8 neutrino events at PandaX-4T

In a liquid xenon time projection chamber, traditional signal search strategy is not sensitive to light dark matter due to the limitation of detection threshold. To overcome this challenge, the PandaX collaboration has developed analyses using customized S1-S2 selections or ionized electron signal only (S2-only). In this talk, we will report the latest search results on light dark matter and solar B8 neutrino-nucleus coherent scattering signals with the PandaX-4T data.

Speaker: Shuaijie Li

45 The first Stars in the Universe as Dark Matter Laboratories

Authors: Cosmin Ilie, Caleb Levy, Jacob Pilawa, Katherine Freese, Saiyang Zhang

The first stars in the Universe, soon to be observed with the James Webb Space Telescope (JWST) can be extremely powerful DM probes. If DM does not play a significant role in the formation of some of the first stars, then, zero metallicity Hydrogen burners (Population III stars) form. Conversely, for scenarios where DM plays a significant role during the formation of a star from a primordial gas cloud, Dark Stars (DS) can form. The later are powered by DM annihilations and can grow to be supermassive (SMDSs), with masses as large as a million suns. As such, SDMSs are easily observable with JWST. The discovery of any Dark Star would constitute indirect evidence of annihilating Dark Matter. For more details on Dark Stars please see talk by Katherine Freese: “Dark Stars in JWST and Roman Space Telescope.” In our presentation we mainly focus on the role of Population III stars as DM laboratories, and how the method we propose complements Direct Detection experiments, as explained in detail in PRD 104 (123031).

Dark matter (DM) can be trapped by the gravitational field of any star, since collisions with nuclei in dense environments can slow down the DM particle below the escape velocity (vesc) at the surface of the star. If captured, the DM particles can self-annihilate, and, therefore, provide a new source of energy for the star. We investigate this phenomenon for capture of DM particles by the first generation of nuclear burning stars [Population III (Pop III) stars], by using the multiscatter capture formalism. Pop III stars are particularly good DM captors, since they form in DM-rich environments, at the center of ∼10^6 M⊙ DM minihalos, at redshifts z ∼ 15. Assuming a DM-proton scattering cross section (σ) at the current deepest exclusion limits provided by the XENON1T experiment, we find that captured DM annihilations at the core of Pop III stars can lead, via the Eddington limit, to upper bounds in stellar masses that can be as low as a few M⊙ if the ambient DM density (ρX) at the location of the Pop III star is sufficiently high. Conversely, when Pop III stars are identified, one can use their observed mass to place bounds on the product between the ambient DM density and the proton-DM scattering cross section (sigma). Using adiabatic contraction to estimate the ambient DM density in the environment surrounding Pop III stars, we place projected upper limits on σ, for Pop~III stars in the 100 M⊙–1000 M⊙ range, and find bounds that are competitive with, or deeper than, those provided by the most sensitive current direct detection experiments for both spin-independent and spin-dependent (SD) interactions, for a wide range of DM masses. Most intriguingly, we find that Pop III stars with mass M⋆ ≳ 300 M⊙ could be used to probe the SD proton-DM cross section below the “neutrino floor,” i.e. the region of parameter space where DM direct detection experiments will soon become overwhelmed by neutrino backgrounds. Conversely, if Direct Detection experiments pin down the proton-DM cross section, our method can be used to constrain the DM densities at the center of high redshift mini halos, a parameter which is unaccessible via current or foreseeable future dynamic measurements and for which we currently only have simulations to rely on.

Speaker: Cosmin Ilie (Colgate University)

UCLADMPOPIII.pdf

46 Peering into the Gap: Learning about Dark Matter from the Pair Instability Mass Gap

Authors: Joshua Ziegler and Katherine Freese

Current models of stellar evolution predict a lack of black holes in the mass range 50-140 solar masses. We explore one way that introducing dark matter to this stellar evolution could influence this mass gap. In particular, given appropriate conditions, it is possible that the addition of dark matter may offer a way to produce black holes throughout this mass gap. In addition, we explore how dark matter could play a role in producing stellar evolution effects that could be observable.

Speaker: Joshua Ziegler

Dark Star Poster.pdf

47 Kinetic Simulations of Collisionless Shock Formation in the Dark Sector

Authors: Pierce Giffin and William DeRocco

Historically, dark matter searches have primarily focused on hunting for effects from two-to-two scattering. However, given that the visible universe is primarily composed of plasmas governed by collective effects, there is great potential to explore similar effects in the dark sector. Recent semi-analytic work has shown that new areas of parameter space for dark U(1) models can be probed through the observation of collisionless shock formation in astrophysical dark plasmas, a nonlinear process that requires simulation. Here, I will show initial results from simulating such warm, non-relativistic pair plasmas within the EPOCH framework, a fully-kinetic particle-in-cell plasma physics simulation suite.

Speaker: Pierce Giffin

Kinetic Simulations of Collisionless Shock Formation in the Dark Sector.pdf

48 Analyzing High-Redshift Galaxy Candidates as Supermassive Dark Star Candidates with JWST Data

Authors: Cosmin Ilie, Jillian Paulin

The nature of the first stars in the universe is, of yet, an unresolved problem in cosmology. One theoretical model is supermassive dark stars (SMDS), which would be powered predominantly by dark matter annihilation. The launch of JWST has led to the discovery of many high-redshift galaxy candidates. This presents a dilemma: present cosmological simulations predict a much smaller number of very massive galaxies than we are now observing from JWST. We present a possible solution to this dilemma: that some of these galaxy candidates may actually be supermassive dark star candidates. We compare JWST photometric data for unresolved or poorly resolved high redshift galaxy candidates, including GLASS-z12, JADES-GS-z10, and JADES-GS-z13, with spectral energy distributions from model SMDS and find that SMDS models can better represent observational data in comparison to current Lyman-break galaxy models. To definitively distinguish SMDS from galaxies, we will need to analyze spectroscopic data and look for a He-II feature at 1640 angstroms. In SMDS, this will be an absorption feature, whereas in Population III galaxies this will be an emission feature.

Speaker: Jillian Paulin (Colgate University)

Paulin_UCLA_DM.pdf

Paulin_UCLA_DM.pptx

49 Probing Dark Matter with exoplanets

Authors: Cosmin Ilie and Caleb Levy

One approach to understanding Dark Matter (DM) involves studying how it interacts with compact astrophysical objects. Through interactions with an object’s constituents, DM in the region around an object can become gravitationally bound inside the object (capture) and, if DM undergoes annihilation processes, can leave an observable imprint on the object. Additionally, captured DM can escape the object through up-scattering with the object’s nuclei distributions, a process known as evaporation. In Ilie et al. 2020, analytic expressions for the capture rate of DM are computed assuming the object's escape velocity ($𝑣_{𝑒𝑠𝑐}$) far surpasses the DM velocity dispersion ($\bar{v}$). In this work, we generalize those findings and find analytic expressions irrespective of any $\bar{v}-𝑣_{𝑒𝑠𝑐}$ hierarchy. As in Ilie et al. 2020, we find analytic capture rates in four distinct regions of the DM mass ($𝑚_𝑋)$ and scattering cross-section ($\sigma$) parameter space and further find that one of these regions is erased in the $\bar{v} >>𝑣_{𝑒𝑠𝑐}$ limit. These results are important since computing capture rates numerically becomes very computationally expensive in the limit of high DM-baryon interaction.

Exoplanets are promising candidates for probing DM through these processes, particularly in the sub-GeV regime, as described in Leane and Smirnov 2021 who compute their sensitivity to DM at masses where evaporation is negligible. In this work, we improve on their results by including completely the effects of evaporation in addition to capture and annihilation. We compute our evaporation rate as per Garani and Palomares-Ruiz 2022, which includes the suppression from the so-called "ping-pong" effect whereby DM particles on outbound trajectories with speed $𝑣_𝑋>𝑣_{𝑒𝑠𝑐}$ down scatter and thus become effectively "re-captured." This effect adds a non-trivial dependence of the evaporation rate ($E$) on the scattering cross-section ($\sigma$), as opposed to the usual $E \sim \sigma$ when the ping-pong effect is excluded. With this non-trivial dependence, we find that, while sensitivity to DM is reduced when considering the effects of evaporation, these objects still serve as strong probes of DM below the mass where evaporation begins to dominate.

Speaker: Caleb Levy

50 Searching for High-Frequency Gravitational Waves with ABRACADABRA-10cm

Gravitation wave searches have been mainly focused on the nHz to kHz frequency range, corresponding to known astrophysical objects. We focus our search instead on higher frequencies which may indicate signs of in-spiraling primordial black holes, or other beyond the standard model phenomena. ABRACADABRA-10cm has had great success as a lumped-element axion experiment; using the electromagnetic dynamics of gravitational waves and a simple change of pickup structures, we are able to use the ABRACADABRA detector to search for these high-frequency gravitational wave in the kHz to MHz range. I will present on the design and first data from the ABRACADABRA-10cm high-frequency gravitational wave search.

Speaker: Kaliroe Pappas (Massachusetts Institute of Technology, Laboratory For Nuclear Science)

UCLAPoster.png

51 𝑆8 Tension in the Context of Dark Matter-Baryon Scattering

Authors: Adam He, Rui An, Vera Gluscevic, Mikhail M. Ivanov

We explore an interacting dark matter (IDM) model that allows for a fraction of dark matter (DM) to undergo velocity-independent scattering off of baryons. In this scenario, structure on small scales is suppressed relative to the cold DM scenario. Using the effective field theory of large-scale structure, we perform the first systematic analysis of BOSS full-shape galaxy clustering data for the interacting scenario, and we find that this model alleviates the $𝑆_8$ tension between large-scale structure (LSS) data and Planck CMB data. Adding the $𝑆_8$ prior from DES in our analysis further leads to a mild $\sim 3 \sigma$ preference for non-vanishing DM-baryon scattering, assuming ∼10% of DM is interacting, and has particle mass of 1 MeV. Such scenario is consistent with other small-scale structure observations, and produces a modest $\sim$20% suppression of the linear power at $𝑘< \sim 1 ℎ$/Mpc. Our results can be interpreted as a pointer to the early-time power suppression on small scales as a desirable and generic feature that may have the potential to resolve $𝑆_8$ tension between cosmological data sets. The validity of the specific interacting DM model explored here will be critically tested with incoming survey data.

Speaker: Adam He

Adam He Poster-2.pdf

52 Structure Formation and the Global 21-cm Signal in the Presence of Coulomb-like Dark Matter-Baryon Interactions

Interactions between dark matter (DM) and baryons in which the cross section scales with relative particle velocity as $𝑣^{−4}$ has enjoyed a lot of attention in DM literature as a generalization of the popular millicharge model. This model has interesting astrophysical phenomenology and was previously proposed as a mechanism to cool down hydrogen at Cosmic Dawn and alter the global 21-cm signal. In this work, we present the first self-consistent modeling of the effect of $𝑣^{−4}$ DM–baryon scattering that accounts for the effects of interactions on structure formation, in addition to their effects on the thermal history of hydrogen. We show that 𝑣−4 scattering with cross sections needed to significantly alter the temperature of baryons also significantly suppresses and delays the growth of structure at epochs relevant for the 21-cm signal, implying that the two effects should be considered jointly. We show that in the context of the EDGES anomaly, consideration of both effects entirely eliminates millicharge as a viable model, even in absence of any other observational bounds. For the case of $𝑣^{−4}$ scattering with neutral targets, the same effects dramatically narrow the viable parameter space. These results critically inform modeling of the global 21-cm signal and structure formation in cosmologies with DM–baryon scattering, with repercussions for future and upcoming cosmological data analysis.

Speaker: George Driskell (University of Southern California)

53 Recent progress on BSM and dark matter searches in CUORE

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

Speaker: Rebecca Kowalski

UCLA Poster Vertical Final.pdf

54 Extremes in Mixing Angle Space: Constraining Sterile Neutrinos for the Next Generation of Searches

Sterile neutrinos represent a clear extension of the Standard Model with multiple potential cosmological signatures. We numerically follow the cosmic production of sterile neutrino dark matter to constrain the mass-mixing angle parameter space, leading to a better understanding of the models which remain viable for further study in future experimental probes. In the small mixing angle regime, we study Shi-Fuller-based production or models with enhanced active sector self-interaction, which furthers the possibility that sterile neutrinos comprise the majority of the dark matter. In the high mixing angle regime, we explore possible mechanisms of suppressing production of keV scale sterile neutrinos, within the HUNTER experiment parameter space. Some of these new physics paths include universes with a nontrivial cosmic lepton number, new neutrino interactions with light bosons, late-time neutrino mass generation, low reheating temperature universes, or phase transitions in the early universe.

Speakers: Cannon Vogel (UC Irvine), Helena Garcia Escudero (UCI)

Extremes in Mixing Angle Space_ Sterile Neutrino Sensitivity in the Next Generation of Searches.pdf

55 Core Collapse in Self-Interacting Dark Matter Halos

Self-interacting dark matter (SIDM) is compelling because it could solve the small-scale structure formation problems and it arises generically in new physics models with dark sectors. Using simulations of the Milky Way with moderate cross sections, we motivate velocity-dependent cross sections with large values for the cross section at the velocities relevant for dwarf halos. These cross section values would allow core collapse to occur in some Milky Way subhalos such that they would be dense enough to match the densest ultra-faint and classical dwarf spheroidal galaxies in the Milky Way. Some of these halos may also be driven into the short-mean-free-path (SMFP) regime. We discuss the structure of the SMFP core, the relevant scaling relations, and how they depend on the particle physics model. We show a new approximate universality for the first time that improves predictions of the SMFP evolution and the mass of the black hole likely to be left behind.

Speakers: Maya Silverman, Sophia Gad-Nasr

CoreCollapseinSIDMHalos_UCLADM.pdf

56 Corrections to Hawking Radiation from Asteroid Mass Primordial Black Holes: I. Formalism of Dissipative Interactions in Quantum Electrodynamics

Authors:Arijit Das, Christopher Hirata, Emily Koivu, Makana Silva, Gabriel Vasquez

Primordial black holes (PBHs) within the mass range 10$^{17}$ - 10$^{22}$ g are a favorable candidate for describing part of or all the dark matter in the Universe. Towards the lower end of this mass range the Hawking temperature is approximately 100 keV or higher, allowing for the creation of electron - positron pairs; thus making Hawking radiation a useful constraint for most current and future MeV surveys. This motivates the need for realistic and rigorous accounts of the distribution and dynamics of emitted particles from Hawking radiation in order to properly model detected signals from high energy observations. In this talk, we discuss the first in a series of papers to account for the $O(\alpha)$ correction to the Hawking radiation spectrum on a Schwarzchild spacetime.

Speaker: Gabriel Vasquez (The Ohio State University)

57 New technologies for future direct detection LXe TPCs: a large-diameter test platform and hermetic TPC

Future liquid xenon direct-detection experiments, such as DARWIN, need to be larger and cleaner than those currently running. Both of these goals will certainly require advances in detector technology.
The Pancake facility, with its 3 m diameter cryostat, allows the development and testing of individual full-scale components such as new electrodes in an environment very similar to the experiments where they will eventually be used. This poster will present the facility as well as the successful operation of “hermetic TPC”, where the sensitive region is isolated from the region surrounding it. Since most radon is emanated from outside the TPC itself, this can help reduce the background level for dark matter searches.

Speaker: Adam Brown (University of Freiburg)

BrownUCLA2023.pdf

58 Dark matter particle mass and properties from scaling laws in galaxy rotation curves and N-body simulations

We present a theory to estimate dark matter particle mass, size and other properties based on the scaling laws identified from galaxy rotation curves and N-body simulations (Illustris project etc.). The existence of energy cascade in the hierarchical formation of dark matter halos leads to a two-thirds power law for kinetic energy and a four-thirds power law for halo core density with the length scale r. Both scaling laws can be directly confirmed by N-body simulations and rotation curves. For collisionless dark matter with gravity as the only interaction, these scaling laws can be extended down to the smallest scale, where quantum effects become important. This extension suggests a possible heavy dark matter scenario with a particle mass of $\sim 10^{12}$ GeV. Potential extension of the theory to self-interacting dark matter is also presented to identify constraints on the cross section of self-interaction.

Accompanying slides and datasets for this work can be found at https://doi.org/10.5281/zenodo.6569901.

Speaker: Zhijie (Jay) Xu (Pacific Northwest National Laboratory)

DM_Poster_Zhijie_Jay_Xu_PNNL.pdf

Thursday, 30 March

Morning coffee

SESSION 5: Astrophysics and Cosmology-1 (CHAIR: Graciela Gelmini- UCLA)

59 DM GHOSts: Anomalous low-mass structures induced by the supersonic relative velocity between dark matter and baryons

A supersonic relative velocity between dark matter (DM) and baryons--the stream velocity--at the time of recombination induces the formation of low-mass objects with anomalous properties in the early universe. We investigate objects we term Dark Matter + Gas Halos Offset by Streaming (DM GHOSts)--diffuse, DM-enriched structures formed because of a physical offset between the centers of mass of DM and baryonic overdensities. We present an updated numerical investigation of DM GHOSts and Supersonically Induced Gas Objects (SIGOs), including the effects of molecular cooling, using high-resolution hydrodynamic simulations run with the AREPO code. We find that the stream velocity causes deviations from sphericity in both the gas and dark matter components and lends greater rotational support to the gas. Further, low-mass objects demonstrate core-like rotation and mass profiles. Anomalies in the rotation and morphology of DM GHOSts could represent an early universe analog to observed ultra-faint dwarf galaxies with variations in DM content and unusual rotation curves.

Speaker: Claire Williams (University of California - Los Angeles)

60 Effect of the Large Magellanic Cloud on dark matter direct detection

The Large Magellanic Cloud (LMC) can impact the dark matter halo of the Milky Way, and boost the dark matter velocity distribution in the Solar neighborhood. Cosmological simulations that sample potential Milky Way formation histories are powerful tools, which can be used to characterize the signatures of the LMC’s interaction with the Milky Way, and can provide crucial insight on the LMC’s effect on the local dark matter distribution. I will discuss the signatures of the LMC on the local dark matter distribution in state-of-the-art cosmological simulations, and its implications for dark matter direct detection.

Speaker: Nassim Bozorgnia (University of Alberta)

Bozorgnia-UCLA2023.pdf

61 The Primordial Black Holes Variations

In the age of gravitational wave astronomy and direct black hole imaging, the possibility that some of the black holes in the universe have a primordial, rather than stellar origin, and that they might be a non-negligible fraction of the cosmological dark matter, is quite intriguing. I will review the status of the field, and comment on search strategies and future prospects for detection across many decades in black hole mass. I will also discuss how light primordial black holes could seed both baryonic and particle dark matter in the very early universe.

Speaker: Stefano Profumo

62 What does cosmology tell us about dark matter mass and interactions?

Cosmological observables, from the CMB anisotropy to the census of galaxies in the early and local universe, offer the most direct and broad tests for the nature of dark matter, including a number of scenarios that are challenging or even impossible to test in a laboratory setting. I will review the status of the recent early-universe and late-universe searches for the identity of dark matter, summarizing the best current limits on scattering between dark matter and baryons, the non-thermal production mechanisms for sterile neutrinos, and mass bounds on thermal-relic dark matter. I will highlight the interplay between complementary probes of dark matter physics, using the example of the 21-cm signal from the Cosmic Dawn, the CMB primary anisotropy, and substructure in the Milky Way. Finally, I will discuss the prospects for unveiling the physics of dark matter in the coming decade.

Speaker: Vera Gluscevic (University of Southern California)

DM-UCLA-2023-Gluscevic (1).pdf

63 Self-Interacting Dark Matter and Small-Scale Structure

I will discuss recent work on self-interacting dark matter in light of the latest observations and numerical simulations. In particular, I will highlight novel signatures of gravothermal collapse of dark matter halos, a unique prediction if dark matter has strong self-interactions.

Speaker: Hai-Bo Yu (University of California Riverside)

2023UCLA_HBYU.pdf

64 Pushing the Limits of Detectability: Mixed Dark Matter from Strong Gravitational Lenses

One of the frontiers for advancing what is known about dark matter lies in using strong gravitational lenses to characterize the population of the smallest dark matter halos. There is a large volume of information in strong gravitational lens images so the question we seek to answer is to what extent we can refine this information. To this end, I will discuss recent forecasts of the detectability of a mixed warm and cold dark matter scenario using the anomalous flux ratio method from strong gravitational lensed images. The halo mass function of the mixed dark matter scenario is suppressed relative to cold dark matter but still predicts numerous low-mass dark matter halos relative to warm dark matter. Since the strong lens signal is a convolution over a range of dark matter halo masses and since the signal is sensitive to the specific configuration of dark matter halos, not just the halo mass function, degeneracies between different forms of suppression in the halo mass function, relative to cold dark matter, can arise. With a set of lenses with different configurations of the main deflector and hence different sensitivities to different mass ranges of the halo mass function, the different forms of suppression of the halo mass function between the warm dark matter model and the mixed dark matter model can be distinguished.

Speaker: Ryan Keeley (UC Merced)

UCLA_DM_RyanKeeley.pdf

65 Early Dark Matter-less Star Clusters as tests to ΛCDM

In the standard model of structure formation (i.e., ΛCDM), large relative velocities between baryons and dark matter are predicted at the time of recombination. These velocities cause the formation of Supersonically Induced Gas Objects, or SIGOs. SIGOs are a natural consequence of ΛCDM structure formation. In particular, they are characterized by low dark matter abundances and metallicities, and have been suggested as a progenitor candidate for globular clusters (GCs). In this talk, I will show that the abundance of SIGOs in the early Universe in ΛCDM is comparable to the abundance of present-day GCs, and that SIGOs likely formed in our local group. Further I’ll demonstrate how these objects can regularly form stars. Finally, because SIGOs are a natural consequence of structure formation, I would suggest that future JWST detections can serve as a test to ΛCDM.

Speaker: William Lake

UCLA Dark Matter Conference 2023 lake.pdf

UCLA Dark Matter Conference 2023 lake.pptx

66 Dark Stars in JWST and Roman Space Telescope

Dark Stars are stellar objects made (almost entirely) of hydrogen and helium, but powered by the heat from Dark Matter annihilation, rather than by fusion. They are in hydrostatic and thermal equilibrium, but with an unusual power source. The relevant types of dark matter for heating the stars include Weakly Interacting Massive Particles (WIMPs), and Self Interacting Dark Matter (SIDM). Although dark matter constitutes only ≲0.1% of the stellar mass, this amount is sufficient to power the star for millions to billions of years. Thus, the first phase of stellar evolution in the history of the Universe may have been dark stars. Starting from their inception at ∼1M⊙ they accrete mass from their surroundings to become supermassive stars, some even reaching masses >10^6M⊙ and luminosities >10^10L⊙, making them detectable with the James Webb Space Telescope and upcoming Roman Space Telescope. Once the dark matter runs out and the dark star dies, it may collapse to a black hole; thus dark stars may provide seeds for the supermassive black holes observed throughout the Universe and at early times.

Speaker: Katherine Freese

Freese DS UCLA 2023 new.pdf

67 Velocity-dependent J-factors in FIRE simulations of Milky-Way size galaxies for indirect detection experiments

I present dark matter indirect detection predictions (J-factors) for the Galactic-center using 12 highly-resolved, hydrodynamic FIRE-2 zoom cosmological simulations of Milky Way size galaxies. In addition to velocity-independent (s-wave) annihilation cross-sections ⟨σv⟩, we also calculate effective J-factors for velocity-dependent models, where the annihilation cross-section is either p-wave (∝ $v^2/c^2$) or d-wave (∝ $v^4/c^4$). Compared to dark-matter-only (DMO) counterparts, the FIRE runs produce central dark matter velocity dispersions that are systematically larger than in DMO runs by factors of ~2.5-4. They also have a larger range of central (~400 pc) dark matter densities than the DMO runs (ρ$_{\rm FIRE}$/ρ$_{\rm DMO}$ ≃ 0.5-3). At 3 deg from the Galactic Center, FIRE J-factors are 3-60 (p-wave) and 10-500 (d-wave) times higher than in the DMO runs. The change in s-wave signal at 3 deg is more modest and can be higher or lower (~0.3-7), though the shape of the emission profile is flatter (less peaked towards the Galactic Centre) and more circular on the sky in FIRE runs. Given that p-wave J-factors that are significantly enhanced compared to most past estimates, contrary to previous expectations, such models may be in the range of detection in the not too distant future.

Speaker: James Bullock (University of California, Irvine)

Bullock_DM2023b.pdf

09:45 Coffee Break

SESSION 6: Astrophysics and Cosmology-2 (CHAIR: Tommaso Treu- UCLA)

68 Fuzzy dark matter constraints using a single VLBI observation of a gravitationally lensed radio jet

Strong gravitational lensing by galaxies provides us with a powerful laboratory for testing dark matter models. Various particle models for dark matter give rise to different small-scale distributions of mass in the lens galaxy, which can be differentiated if the observation is sensitive enough. The sensitivity of a gravitational lens observation to the presence (or absence) of low-mass dark structures in the lens galaxy is determined mainly by the angular resolution of the instrument and the spatial structure of the lensed source.

In this talk, I will present results from the analysis of a global VLBI observation of a gravitationally lensed radio jet. With an angular resolution better than 5 milli-arcseconds and a highly extended, spatially resolved source, we are able to place competitive constraints on the particle mass in fuzzy dark matter models using this single observation. I will also present preliminary results from our analysis of warm dark matter models using this lens system. Our results illustrate the key role that VLBI observations will play in revealing the nature of dark matter, especially in light of the ~10^5 gravitational lens systems with radio-bright sources that will be discovered by the Square Kilometre Array.

Speaker: Dr Devon Powell (Max Planck Institute for Astrophysics)

talk_powell.pdf

69 Cosmological Simulations with Novel Dark Matter Physics

I will describe new cosmological zoom-in simulation suites that accurately resolve small-scale structure in the presence of novel dark matter physics. These simulations target Milky Way and strong lens analogs with initial conditions appropriate for a large variety of warm, interacting, and fuzzy dark matter models at and below current observational limits. Several of these simulations include strong, velocity-dependent dark matter self-interactions that yield distinctive predictions for structure on dwarf galaxy scales. Finally, I will present a new approach to simulate dark matter-baryon scattering in hydrodynamic simulations, and preliminary results.

Speaker: Ethan Nadler

Nadler UCLA 2023.pdf

70 How could we probe the angular dependence of dark matter self-interactions?

Self-interacting dark matter (SIDM) is promising to solve or at least mitigate small-scale problems of cold collisionless dark matter. N-body simulations have proven to be a powerful tool to study SIDM within the astrophysical context. However, it turned out to be difficult to simulate dark matter models that typically scatter about a small angle, for example, light mediator models. We developed a novel numerical scheme for this regime of frequent self-interactions that allows for N-body simulations of systems like galaxy cluster mergers or even cosmological simulations. We have studied various systems and found significant differences between the phenomenology of frequent self-interactions and the commonly studied large-angle scattering (rare self-interactions). For example, in mergers of galaxy clusters, frequent self-interactions can produce larger offsets between galaxies and DM than rare self-interactions. In addition, we find the abundance of satellites to be stronger suppressed for small-angle scattering in galaxy clusters. Generally speaking, we find the most significant differences in the phenomenology of systems far from equilibrium. Consequently, these are the best-suited systems to probe the angular dependence of SIDM.

Speaker: Moritz Fischer (University Observatory Munich)

MoritzFischer.pdf

71 A Model-Independent Radio Telescope Search for Dark Matter in the S Band

Despite attempts to constrain the nature of dark matter over the last few decades, the parameter space has continuously broadened. We have designed a novel search technique for ultralight dark matter using the Breakthrough Listen public data release of Green Bank Telescope data that aims to match the broad theoretical scope with an equally broad model-independent strategy. The search concept depends only on the assumption of decay or annihilation of virialized dark matter to a quasi-monochromatic radio line, and additionally that the frequency and intensity of the line be consistent with most general properties expected of the phase space of our Milky Way halo. Specifically, the search selects for a line which exhibits a Doppler shift with position according to the solar motion through a static galactic halo, and similarly varies in intensity with position with respect to the galactic center [1]. After a development and testing stage performed on a narrow range in the L band, we have completed a full analysis of the S band.

We gratefully acknowledge support from the Heising-Simons Foundation under grants #2018-0989 and #2022-3566, and the Breakthrough Listen program.

1. Aya Keller, et al., Astrophysics Journal 927, 71 (2022).

Speaker: Aya Keller

Keller_Aya_UCLA_March_30_2023.pdf

72 Galaxies in the Epoch of Reionization in Alternative Dark Matter -- Insights from the Thesan Simulations

Many theories of dark matter predict suppression on the linear matter power spectrum at small scales ($k > \sim 10\,{\rm h/Mpc}$). The suppression can lower the abundance of low-mass haloes (galaxies) at high redshift ($z > 6$) and significantly alter the assembly histories of galaxies in the Epoch of Reionization (EoR). In this work, we use variants of the recently published Thesan simulations to explore the impact of warm dark matter (WDM), fuzzy dark matter (FDM), and models featuring dark acoustic oscillations (DAO) on the properties of early galaxies. The Thesan simulations incorporate an on-the-fly radiative transfer solver for ionizing photons and a non-equilibrium hydrogen/helium chemistry solver, on top of the well-tested IllustrisTNG galaxy formation model. We studied halo (stellar) mass function, UV luminosity function, scaling relations (e.g. the mass-metallicity relation), star formation & metal enrichment histories of galaxies. We found distinct signatures of alternative dark matter, which can propagate to galaxies more massive than the cut-off scale in halo mass function. We also found a non-trivial interplay between model assumptions for reionization and alternative dark matter physics.

Speaker: Xuejian Shen

03152023-UCLADM-ThesanAltDM.key

03152023-UCLADM-ThesanAltDM.pdf

73 Searching for the fundamental nature of dark matter in the cosmic large-scale structure

The fundamental nature of dark matter so far eludes direct detection experiments, but it has left its imprint in the large-scale structure (LSS) of the Universe. Extracting this information requires accurate modelling of structure formation and careful handling of astrophysical uncertainties. I will present new bounds using the LSS on two compelling dark matter scenarios that are otherwise beyond the reach of direct detection. Ultra-light axion dark matter, particles with very low mass and astrophysically-sized wavelengths, is produced in high-energy models like string theory ("axiverse"). I will rule out axions that are proposed to resolve the so-called cold dark matter "small-scale crisis" (mass ~ 10^-22 eV) using the Lyman-alpha forest, but demonstrate how a mixed axion dark matter model could resolve the S_8 tension (mass ~ 10^-25 eV) using Planck, ACT and SPT cosmic microwave background data and the BOSS galaxy survey. Further, I will set the strongest limits to-date on the dark matter — proton cross section for dark matter particles lighter than a proton (mass < GeV). The LSS model involves one-loop perturbation theory, a non-cold dark matter halo model and, to capture the smallest scales, a machine learning model called an "emulator", trained using hydrodynamical simulations and an active learning technique called Bayesian optimisation.

Speaker: Keir Rogers

DM_LSS_UCLA_DM_2023.key

74 Small-scale clumping of dark matter and the mean free path of ionizing photons at z = 6

The power spectrum of primordial fluctuations is largely unconstrained at mass scales $\leq 10^9 M_{\odot}$. A number of alternatives to the cold, collisionless dark matter (CDM) paradigm have been proposed which either suppress or enhance power at these mass scales. The best limits on these models currently come from the Ly$\alpha$ forest flux power spectrum and strong gravitational lensing systems. I will discuss a potential complementary probe: the ionizing photon opacity of the intergalactic medium during reionization, as quantified by the mean free path (MFP). At high redshift, the MFP is directly affected by the presence of structure on $10^4 - 10^8 M_{\odot}$ scales, potentially offering a window into scales inaccessible to other probes, and at an earlier epoch of structure formation. Further motivating this investigation is the recently measured short MFP at $z = 6$ by Becker et al. (2021), which, if confirmed, may already provide evidence for small-scale power. I will discuss our efforts to model the $z \sim 6$ MFP in models with alternative dark matter cosmologies and comment on the usefulness of the MFP as a probe of small-scale structure in the universe.

Speaker: Christopher Cain (University of California, Riverside)

cain_dm_mfp_talk.pdf

75 Cosmic-Ray Antinuclei from Dark Matter and the GAPS Experiment

The discovery of cosmic antinuclei would be an unambiguous signal of new physics and transform the field of cosmic particle research. The GAPS Antarctic balloon payload, scheduled for its initial flight in the upcoming year, is the first experiment optimized specifically for cosmic antiprotons, antideuterons, and antihelium as signatures of dark matter. The distinctive GAPS particle identification technique relies on a system of >1000 lithium-drifted silicon (Si(Li)) detectors, which both capture an incoming antinucleus into an exotic atom and measure the resulting X-ray and nuclear annihilation products, surrounded by a precision-timing, large-area time-of-flight system. In this talk, I will detail preparation of the GAPS payload for initial flight and the potential impact of these measurements in the coming years.

Speaker: Philip Von Doetinchem (University of Hawaii at Manoa)

2303_gaps_ucla_dm_pvd.pdf

76 The GRAMS (Gamma-Ray and AntiMatter Survey) Project

GRAMS (Gamma-Ray and AntiMatter Survey) is a proposed balloon/satellite mission that will be the first to target both MeV gamma-ray observations and antimatter-based indirect dark matter searches 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. In this talk, I will give the current status of the GRAMS project and an overview of the prototype detector testing.

Speaker: Tsuguo Aramaki

UCLADM2023_GRAMS_TsuguoAramaki.pdf

12:35 Lunch Break

SESSION 7: Searches at Accelerators (CHAIR: Jay Hauser - UCLA)

77 Recent dark-sector results from Belle II

The Belle II experiment at the SuperKEKB collider has unique sensitivity to 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 long-lived scalar particles and Z’ decays; as well as the near-term prospects for other dark-sector searches.

Speaker: Steven Robertson (IPP / University of Alberta)

Robertson_UCLADM2022_final.pdf

78 Recent Results of Dark Sector Searches with the BaBar Experiment

Many scenarios of physics beyond the Standard Model predict new
particles with masses well below the electroweak scale. Low-energy, high
luminosity colliders such as BABAR are ideally suited to discover these
particles. We present several recent searches for low-mass dark sector
particles at BABAR, self-interacting dark matter, axion like particles
and dark sector particles produced in B meson decays. These examples
demonstrate the importance of B-factories in fully exploring low-mass
new physics and dark sectors.

Speaker: Brian Shuve (Harvey Mudd College)

Shuve_BaBar.pdf

79 New Results from the Heavy Photon Search Experiment

The Heavy Photon Search experiment (HPS) at the Thomas Jefferson National Accelerator Facility searches for electro-produced dark photons.
We present results from the 2016 Engineering Run consisting of 10608/nb of data for both the prompt and displaced vertex searches.
A search for a resonance in the e+e− invariant mass distribution showed no evidence of signal, in
agreement with previous searches. The search for displaced vertices showed no evidence of excess
signal over background in the masses between 60 and 150 MeV, but had insufficient luminosity to
limit canonical heavy photon production. HPS has taken high-luminosity data runs in 2019 and 2021 that will explore new dark
photon phase space. We also present plans for model specfic interpretations of our data in the future, one example being SIMPs.

Speaker: Cameron Bravo

bravoUCLADM23.pdf

80 First search for inelastic dark matter at the LHC with the CMS detector

Searches for dark matter at the LHC have largely focused on WIMPs, but what if instead of just one dark matter species, there exists a richer dark sector hidden from ordinary view? This opens up a whole new paradigm for dark matter searches, allowing us to focus not only on the coupling between dark matter and the standard model, but also on the interactions between dark matter constituents themselves. The LHC is in a unique position to investigate such a rich dark sector, which is otherwise difficult to probe with direct and indirect detection techniques. In this talk, I will report the hot-off-the-press results of the first search for inelastic dark matter (IDM) at the LHC with the CMS detector. IDM predicts a unique and striking long-lived final-state signature, which can be exploited to access a significant fraction of unexplored dark matter parameter space. This parameter space is especially interesting because of the compatibility with the thermal-relic dark matter abundance leftover from the early universe.

Speaker: Andre Frankenthal (Princeton University (US))

Frankenthal_CMS_iDM_UCLADM23.pdf

81 First results of the PADME Experiment and near-term plans

PADME is a fixed-target missing-mass experiment that searches for the dark photon and other dark sector particles using a beam of positrons with maximum energy of 500 MeV. The detector, located at the Laboratori Nazionali di Frascati near Rome, Italy, has already collected initial physics-grade data over the last few years. Here we present the first physics results of PADME, including one of the most precise measurements to date of the total cross-section of electron-positron annihilation into photons. We also discuss near-term plans for the experiment, such as a direct search for on-shell X17 production, for which data taking is currently ongoing. PADME is likely capable of providing independent confirmation of the excesses observed in the ATOMKI spectroscopic measurements with Beryllium and Helium. These prospects will also be discussed.

Speaker: Andre Frankenthal (Princeton University (US))

Frankenthal_PADME_UCLADM23.pdf

82 The FASER experiment

FASER, the ForwArd Search ExpeRiment, is an LHC experiment located 480 m downstream of the ATLAS interaction point, along the beam collision axis. FASER and its sub-detector FASERnu have two physics goals: (1) to detect and study TeV-energy neutrinos, the most energetic neutrinos ever detected from a human-made source, and (2) to search for new light and very weakly-interacting particles. FASER was designed, constructed, installed, and commissioned during 2019-2022 and has been taking physics data since the start of LHC Run 3 in July 2022. This talk will present the status of the experiment, including detector design, detector performance, and first physics results from Run 3 data.

Speaker: David Casper (UC Irvine)

Casper_FASER.pdf

Casper_FASER.pptx

SESSION 8: Sterile Neutrinos (CHAIR: George Fuller- UCSD)

83 Astrophysical Constraints on Warm Dark Matter

In the regime of linear growth of structure, dark matter dominates structure formation at all scales. On small scales, the thermal and kinetic properties of dark matter will alter the growth of structure at a finite scale that depends on the nature of dark matter. I will review the methods for constraining matter clustering on small scales, highlighting those most robust to modeling and data uncertainties. I will also review the impact of these constraints on leading candidate warm dark matter models, including sterile neutrino and gravitino dark matter models, with our work providing more accurate descriptions of structure formation in the case of gravitino warm dark matter. Our other recent work combines strong lensing and galaxy counts to provide among the strongest constraints yet on warm dark matter, with a corresponding significant (greater than 50%) suppression of structure at $M <8\times 10^6 M_\odot$, well below dwarf galaxy scales, requiring thermal warm dark matter particle masses at approximately $m_\mathrm{th} > 9$ keV.

Speaker: Prof. Kevork N. Abazajian

UCLA DM 2023 Abazajian.key

UCLA DM 2023 Abazajian.pdf

84 Search for keV-scale sterile neutrinos with KATRIN/TRISTAN

Sterile neutrinos are a natural extension of the Standard Model of particle physics. If their mass is in the keV range, they are a viable dark matter candidate. One way to search for sterile neutrinos in a laboratory-based experiment is via tritium beta decay, where they would manifest themselves as a characteristic spectral distortion. The direct neutrino mass experiment, KATRIN, provides high luminosity gaseous tritium source. Equipped with a novel multi-pixel silicon drift detector system (named TRISTAN), the KATRIN experiment has the possibility to search for a keV-scale sterile neutrino signal. This presentation will give an overview of the TRISTAN project, including the status of the detector development and new sensitivity studies.

Speaker: Andrew Gavin

TRISTAN_UCLADM2023.pdf

85 The HUNTER Sterile Neutrino Search

The HUNTER experiment (Heavy Unseen Neutrinos from Total Energy-
momentum Reconstruction) uses missing-mass reconstruction of electron-capture beta decays to search for sterile neutrinos with masses in the 20-280 keV range. We study electron-capture decays of radioactive 131-Cs atoms, contained in a magneto-optical (laser) trap (MOT). The recoil 131-Xe nuclei and the Auger electrons will be measured with part-per-thousend resolution and up to 4$\pi$ collection efficiency using precision MOTRIMS spectrometers. K x-rays will be detected in a YAP scintillator array. The HUNTER vessel has passed UHV tests, and the loading MOT adapted for use with radioactive 131-Cs has been tested with inactive Cs. Mounting of detectors is in progress now at the UCLA experiment site. The apparatus also makes possible other sensitive searches for BSM physics in beta decays.

Talk presented for the HUNTER Collaboration. We thank the W. M. Keck Foundation, the Gordon and Betty Moore Foundation, and our respective universities for financial support of HUNTER.

Speaker: Paul Hamilton (UCLA)

UCLA Dark Matter 2023.pdf

UCLA Dark Matter 2023.pptx

86 MAGNETO-ν: Searching for keV sterile neutrino dark matter in 241Pu beta decays

Sterile neutrino of keV-scale mass is one of strong dark matter candidates. One of the ways for observing “sterile” neutrino is using nuclear beta decays. Non-zero mixing of sterile neutrino to electron neutrino allows them being emitted in nuclear beta decays, which modifies the shape of beta decay spectrum by adding a 4-th spectral component with reduced end-point energy. This modification produces the “kink” structure at the end-point of the sterile neutrino contribution in the beta spectrum, where is the decay Q value minus the mass of sterile neutrino. MAGNETO-ν experiment is a search for keV sterile neutrino in 241Pu beta decays with magnetic quantum sensors. Enriched 241Pu sources will be fully embedded into the magnetic quantum sensors and full decay energies from 241Pu beta decays will be measured with an energy resolution of O(10 eV). In this talk, experimental overview as well as our first 241Pu measurement with a preliminary limit on keV sterile neutrino mixing will be presented.

Speaker: Geon-Bo Kim (LLNL)

Kim_UCLA_DM_MAGNETO.pdf

16:05 Coffee Break

SESSION 9: Dark Matter Theory (CHAIRS: Volodymyr Takhistov- QUP-KEK, Japan, and Edoardo Vitagliano- Hebrew U. of Jerusalem, Israel)

87 Strong Supernova 1987A Constraints on Bosons Decaying to Neutrinos

If existing, feebly interacting particles such as sterile neutrinos, axion-like particles, and others could have been abundantly produced in the core formed during the collapse of Sanduleak in 1987. The duration of the neutrino burst detected at Kamiokande II and at the Irvine–Michigan–Brookhaven (IMB) experiment depended on the cooling speed of the newly formed proto-neutron star at the center of SN 1987A, and hence is often used to constrain these particles. However, particles arising from physics beyond the standard model can be produced inside the core and decay afterwards with large energies. In this talk I will focus on bosons coupling to neutrinos, evoked to open up the parameter space of sterile neutrinos as a dark matter candidate. I will show that the lack of 100-MeV events from SN 1987A implies bounds on the coupling up to one order of magnitude more stringent than both the bounds obtained from Big Bang Nucleosynthesis and from the energy-loss argument.

Speaker: Edoardo Vitagliano

talk_SNneutrinoUCLA.pdf

88 Cosmology of Axion Rotation

We will introduce new cosmological dynamics of the QCD axion, where the axion field rotates in field space. Axion dark matter may be produced from the kinetic energy of the rotation and the required axion decay constant is much below the prediction of the conventional evolutions. The angular momentum of the rotation is transferred into baryon asymmetry through baryon number violating interactions. We discuss the electroweak sphaleron process and some beyond-standard model processes and predictions on the parameters of each theory.

Speaker: Keisuke Harigaya (University of Chicago)

Harigaya (1).pdf

89 Dark matter direct detection from single phonons to nuclear recoils

In most direct detection experiments, the free nuclear recoil description of dark matter scattering breaks down for masses ≲ 100 MeV, or when the recoil energy is comparable to a few times the typical phonon energy. For dark matter lighter than 1 MeV, scattering via excitation of a single phonon dominates and has been computed previously, but for the intermediate mass range or higher detector thresholds, multiphonon processes dominate and are challenging to compute. In this talk, I present an analytic description of dark matter scattering that connects the single phonon, multiphonon, and the nuclear recoil regimes. I discuss the theoretical assumptions of the calculation and present results for dark matter in the keV-GeV mass range.

Speaker: Tongyan Lin

2023_03_30_UCLA.pdf

90 Light thermal dark matter and MeV gamma-ray observation

Light thermal dark matter, whose mass is below 1GeV, is an attractive candidate for dark matter, as its abundance in the present universe is well explained by the thermal freeze-out mechanism. At the same time, it may solve the so-called core-cusp problem via its strong enough self-scattering. We study a minimal model for a light scalar dark matter as an example of such a candidate, requiring a light scalar mediator to address the core-cusp problem and interact with the standard model particles. We analyze the model comprehensively by focusing on the Breit-Wigner resonance for dark matter annihilation and self-scattering channels, considering the thermal relic abundance condition that includes the early kinetic decoupling effect, as well as the present and future constraints from collider, direct, and indirect dark matter detections. We found that the scalar dark matter with a mass of 0.3-2 GeV remains uncharted, which will be efficiently tested by the near future MeV gamma-ray observations.

Speaker: Dr Shigeki Matsumoto (Kavli IPMU)

ShigekiMATSUMOforPDF.pdf

91 New Constraints on Dark Matter, Cosmic Neutrino Profiles, and Neutrino Masses through Gravity and Quantum Sensors

We derive purely gravitational constraints on dark matter and cosmic neutrino profiles in the solar system using asteroid (101955) Bennu.
We focus on Bennu because of its extensive tracking data and high-fidelity trajectory modeling resulting from the OSIRIS-REx mission. We find that the local density of dark matter is bound by $\rho_{\rm DM} < 3.3\times 10^{-15}\;\rm kg/m^3 \simeq 6\times10^6\,\bar{\rho}_{\rm DM}$, in the vicinity of $\sim 1.1$ au (where $\bar{\rho}_{\rm DM}\simeq 0.3\;\rm GeV/cm^3$). We show that high-precision tracking data of solar system objects can constrain cosmic neutrino overdensities relative to the Standard Model prediction $\bar{n}_{\nu}$, at the level of $\eta\equiv n_\nu/\bar{n}_{\nu} < 1.7 \times 10^{11}(0.1 \;{\rm eV}/m_\nu)$ (Saturn), comparable to the existing bounds from KATRIN and other previous laboratory experiments (with $m_\nu$ the neutrino mass). These local bounds have interesting implications for existing and future direct-detection experiments. Our constraints apply to all dark matter candidates but are particularly meaningful for scenarios including solar halos, stellar basins, and axion miniclusters, which predict overdensities in the solar system. Furthermore, introducing a DM-SM long-range fifth force with a strength $\tilde{\alpha}_D$ times stronger than gravity, Bennu can set a constraint on $\rho_{\rm DM} < \bar{\rho}_{\rm DM}\left(6 \times 10^6/\tilde{\alpha}_D\right)$. These constraints can be improved in the future as the accuracy of tracking data improves, observational arcs increase, and more missions visit asteroids. If time permits, I will also talk about a proposal using space quantum sensors to study ultralight dark matter.

This talk is based on https://arxiv.org/abs/2210.03749 and https://arxiv.org/abs/2112.07674 (Nature Astronomy, 2022).

Speaker: Yu-Dai Tsai (University of California, Irvine)

The Elusive Universe at the Precision Frontier -- Yu-Dai Tsai

Yu-Dai_Tsai.pdf

Yu-Dai_Tsai.pptx

92 Axion detection with optomechanical cavities

We propose a novel technique to search for axions with an optomechanical cavity filled with a material such as superfluid helium. Axion absorption converts a pump laser photon to a photon plus a phonon. The axion absorption rate is enhanced by the high occupation number of coherent photons or phonons in the cavity, allowing our proposal to largely overcome the extremely small axion coupling. The axion mass probed is set by the relative frequency of the photon produced in the final state and the Stokes mode. Because neither the axion mass nor momentum need to be matched to the physical size of the cavity, we can scale up the cavity size while maintaining access to a wide range of axion masses (up to a meV) complementary to other cavity proposals.

Speaker: Clara Murgui

UCLA_DM.pdf

93 SUSY dark matter: waxing, not waning

Solving the SM finetuning problems requires introduction of both SUSY and PQ symmetry, all in a stringy context for unification with gravity. Discrete R-symmetries which emerge from string compactifications can generate an approximate, accidental PQ symmetry in the SUSY DFSZ type model with axion decay constant related to the SUSY breaking scale in the cosmological sweet spot, with R-parity conservation as a byproduct while solving the SUSY mu problem and axion qualiy problem. In such a context, the dark matter is of mixed axion/higgsino-like neutralino (multicomponent) where the presence of axinos, saxions, gravitinos and moduli all influence the ultimate dark matter abundance. Thus, the early universe is likely much more complex than the standard thermal WIMP paradigm.

Speaker: Howard Baer

ucla_2023.pdf

94 Dark Matter Direct Detection and Collider Search Complementarity

We analyze the preferred SUSY parameter space that is in agreement with the Dark Matter (DM) relic density, the direct detection (DD) bounds, the LHC searches as well as $(g-2)_\mu$. Seven different scenarios are identified. For each scenario we analyze the complementarity between future DD experiments and direct searches at the (HL-)LHC and future $e^+e^-$ colliders. It is demonstrated that only a combined analysis can conclusively test this model.

Speaker: Sven Heinemeyer (CSIC (Madrid, ES))

sven.pdf

95 Spin 3/2 FIMP: direct detection and collider bounds

We present a Spin 3/2 FIMP dark matter (DM) candidate. FIMP dark matter is produced via the freeze-in mechanism that generally implies tiny coupling between the DM and the standard model particles, making DM direct detection almost hopeless. This is not the case for a spin 3/2 DM at low reheating temperature, where collider bounds play a fundamental role in constraining the parameter space. We show the viability of the model and discuss the details of the production mechanism and future experiments that can falsify it.

Speaker: Francesco Costa

Costa_UCLA.pdf

96 Constraints on Spin dependent and Spin Independent Dark Matter-Electron Scattering

Authors: Mukesh Kumar Pandey, Chih-Pan Wu, Lakhwinder Singh, C.-P. Liu, Hsin-Chang Chi, Jiunn-Wei Chen, Henry T. Wong

Direct searches of dark matter (DM) through its scattering with electrons have been a rapidly growing field in the past decade. With the low-threshold capabilities of modern detectors in electron recoil (ER) and new ideas inspired by theoretical studies, the coverage of DM mass, mχ, has gradually been extended from sub-GeV towards an increasingly lower reach. So far, most attention is given to the DM-electron interaction which is spin-independent (SI) of both DM and electrons. Various experiments have already set stringent exclusion limits on its cross-section, σ (SI) - e, in the mass range of MeV to GeV. The current best limit above 30 MeV is set by XENON1T for their huge exposure mass and time; in the range of 1−30 MeV, several experiments capitalizing the condensed phases of materials such as semiconductor silicon and germanium show potential improvements upon future scale-up. But, what about spin-dependent (SD) interactions? While there can be numerous models to motivate studies of SD DM-electron interactions from the top down, a more straightforward, bottom-up approach is through nonrelativistic (NR) effective field theory. For this purpose, one has to rely on theoretical analysis. In this work, we try to address the above questions using the atom, Germanium, and Xenon—where most calculations can be carried out using nonrelativistic effective field theory. Basically, we study DM-atom scattering through the SD and SI DM-electron interaction at leading order, using well-benchmarked, state-of-the-art atomic many-body approaches. Exclusion limits are derived from various data of xenon and germanium detectors. The sub-GeV dark matter is a less explored region and is highly motivated for next-generation experiments. Its studies complement the very active research on the SI and SD interactions, and together they can provide a more comprehensive understanding of the nature of DM and its interactions with matter.
This work was supported by the National Science and Technology Council (NSTC) of Taiwan.

Speaker: Mukesh Kumar Pandey (National Dong Hwa University, Taiwan)

Mukesh_UCLA_DM_2023.pdf

Mukesh_UCLA_DM_2023.ppt

97 Experimental signatures for direct, indirect, and collider detection of a 70 GeV dark matter WIMP with precisely-defined second-order gauge couplings

We discuss the potential for discovery of a recently proposed dark matter WIMP which has a mass of about 70 GeV/c$^2$ and only second-order couplings to W and Z bosons. There is evidence that indirect detection may already have been achieved, since analyses of the gamma rays detected by Fermi-LAT and the antiprotons observed by AMS-02 are consistent with 70 GeV dark matter having our calculated $\langle \sigma_{ann} v \rangle \approx 1.2 $\times 10^{-26} $ cm$^3$/s. The estimated sensitivities for LZ and XENONnT indicate that these experiments may achieve direct detection within the next few years, since we estimate the relevant cross-section to be slightly above $10^{-48}$ cm$^2$. Other experiments such as PandaX, SuperCDMS, and especially DARWIN should be able to confirm on a longer time scale. The high-luminosity LHC might achieve collider detection within about 15 years, since we estimate a collider cross-section slightly below 1 femtobarn.

Speaker: Roland Allen

Allen-UCLA-2023.pdf

Banquet

Friday, 31 March

Morning Coffee

SESSION 10: Direct Detection: status of liquid/gas WIMP detectors (CHAIR: Alvine Kamaha -UCLA)

98 Recent progress and plan of PandaX experiment

PandaX experiment uses xenon as target to detect weak and rare physics signals, including dark matter and neutrinos. We are running a new generation detector with 4-ton xenon in the sensitive volume, PandaX-4T. The commissioning run data has pushed the constraints on WIMP-nucleon scattering cross section to a new level. In this talk, I will give an overview of PandaX-4T latest results on dark matter and neutrino physics, exploring the physics capability of xenon detector. I will also briefly discuss the future prospects of PandaX.

Speaker: Ning Zhou

20230331_UCLADM.mov

20230331_UCLADM.pdf

99 The NEWS-G light Dark Matter search experiment: Physics results from a 10 day exposure with pure methane gas

The NEWS-G direct detection dark matter search experiment uses spherical proportional counters (SPCs) with light noble gasses to search for low mass WIMP-like dark matter. The current iteration of the experiment consists of a large 140 cm diameter SPC installed at SNOLAB benefiting from a new sensor design, and improvements in detector performance and data quality. Before its installation at SNOLAB, the detector was operated with 135 mbar of pure methane gas at the Laboratoire Souterrain de Modane inside a temporary water shield, offering a hydrogen-rich target and reduced backgrounds. We present results from a 10-day physics campaign in these conditions, including calibrations of the detector response down to the single ionization regime. The installation of the experiment at SNOLAB and other future works are also presented.

Speaker: Mr Daniel Durnford (University of Alberta)

NEWS-G_UCLA_v2(1).pdf

The NEWS-G light Dark Matter search experiment: Physics results from a 10 day exposure with pure methane gas

100 Recent developments of the PICO dark matter detectors

PICO is currently fielding two large dark matter bubble chamber detectors at SNOLAB.
PICO-40L is the first of a new type of dark matter detector using an improved detector geometry. The detector was recently refurbished with a new cooling system and is operating now at SNOLAB.
At the same time PICO-500, a large dark matter bubble chamber following the same principle as PICO-40L is under construction. Major detector components have been received and are being prepared for shipment to SNOLAB.
We will present our experimental progress and and recent data analysis.

Speaker: Colin Moore

UCLA DM.pdf

101 Dark Matter search results from the LUX-ZEPLIN (LZ) Experiment

LUX-ZEPLIN (LZ) is a direct dark matter detection experiment currently being operated at the Sanford Underground Research Facility (SURF) in Lead, South Dakota. LZ is an instrument that is superlative in many ways. It utilizes 7 tonnes of liquid xenon in a dual phase time projection chamber, surrounded by an instrumented xenon “skin” region and gadolinium-loaded liquid scintillator outer detector all contained within an ultra-pure water tank. The experiment looks for dark matter in the form of Weakly Interacting Massive Particles (WIMPs), as well as a broad range of other novel physics signals. In 2022, LZ released its first WIMP search results with an exposure of 60 live days using a fiducial mass of 5.5 tonnes. These results set new limits on spin-independent and spin-dependent WIMP-nucleon cross-sections for WIMP masses above 9 GeV/c^2. This talk will give an overview of the LZ detector, a description of the first results, and a brief outlook of the diverse science program which will be enabled by the experiment.

Speaker: Dr Maria Elena Monzani

Monzani-UCLA-31Mar23.pdf

102 XENONnT: first WIMP search results

The XENONnT experiment searches for signs of dark matter and physics beyond the Standard Model within a 5.9-tonne xenon target instrumented as a two-phase time projection chamber. I will report about the status of the experiment and present its early physics results.

Speaker: Luca Grandi (The University of Chicago)

grandi_to_upload.pdf

103 DarkSide-20k: The Next Stage in the Direct Dark Matter Search Using Liquid Argon

Dual-phase noble liquid Time Projection Chambers (TPCs) and single-phase scintillation-only detectors offer competitive ways to search for dark matter (DM) directly, via elastically scattering off of detector target nuclei and electrons. Argon possesses an intrinsic property allowing for powerful discrimination between electron (background) and nuclear (signal) recoils in the search for high-mass DM. The Global Argon Dark Matter Collaboration (GADMC) has undertaken an ambitious program from the extraction and purification of Underground Argon (UAr), depleted in 39Ar to reduce the radioactive background, to the development of large arrays of Silicon Photo Multiplier (SiPM) modules capable of resolving single photoelectrons. DarkSide-20k (dual-phase TPC) is the next stage of this program and has entered the construction phase at the Gran Sasso underground laboratory (LNGS) in central Italy. An exposure goal of ≈ 200 tonne-years with near-zero instrumental background has been set for sensitivity to a WIMP-nucleon scattering cross section of ≈ 10^-47 cm2 for a WIMP mass of 1 TeV/c2 over a 10-year run. The DarkSide-20k experimental program and recent progress will be presented.

Speaker: Thomas Nathan Thorpe (University of California Los Angeles (US))

Thorpe_UCLADM_2023.pdf

104 Dark matter search in DEAP-3600: results and prospects

DEAP-3600 is the largest running dark matter detector filled with liquid argon, set at SNOLAB in Sudbury, Canada, 2 km underground. Since 2019 the experiment has held the most stringent exclusion limit in argon for WIMPs above 20 GeV/c$^2$. Such a result is a consequence of the large detector exposure and the extraordinary rejection power achievable in liquid argon against electron recoil backgrounds. DEAP-3600 demonstrated the discrimination power of pulse shape discrimination to the strongest precision to date, with a leakage probability as low as 10$^{-10}$ for a nuclear recoil acceptance of 50 % at about 20 keV of deposited energy.
Recently, the WIMP analysis has been revised in terms of a non-relativistic effective field theory framework in correlation with non-standard velocity distributions in the halo, as suggested by the substructures observed with Gaia and the Sloan Sky Digital Survey. DEAP-3600 set the world's best exclusion limit for xenon-phobic dark matter scenarios. Moreover, a custom-developed analysis has recently pointed out the extraordinary sensitivity to ultra-heavy, multi-scattering dark matter candidates, resulting in world-leading exclusion limits on two composite dark matter candidates up to Planck-scale masses.
In parallel with ongoing analysis, involving both dark matter searches and measurements on the $^{39}$Ar $\beta$ decay spectrum and activity, the detector is undergoing upgrades with the aim to further mitigate the alpha-induced scintillation in the neck of the detector, which has limited the sensitivity to WIMPs up to now. Such R&D, including the pyrene coating of the flow guides and the external cooling system, will decrease this background and eventually enhance the detector sensitivity in the upcoming WIMP search.

Speaker: Dr Michela Lai

DEAP_ucla2023-compressed.pdf

105 DARWIN and the Future of Liquid Xenon Dark Matter Detectors

Liquid xenon time projection chambers are established as a leading dark matter detector technology. LZ and XENONnT are in the midst of sweeping exciting parameter space for Weakly Interacting Massive Particles (WIMPs) and other rare particle physics phenomena. Regardless of a dark matter signal observation in the current generation of detectors, it is important to look to a future experiment that would be limited in its discovery potential by irreducible neutrino backgrounds rather than exposure. In this talk, I present the status of the DARWIN experiment, and particularly highlight the expected science reach for WIMPs, coherent elastic neutrino-nucleus scattering, and neutrinoless double beta decay. I will also give a brief introduction to the XLZD consortium and our goal to build the ultimate liquid xenon dark matter detector.

Speaker: Abigail Kopec (UC San Diego)

Kopec_DARWIN.pdf

106 New constraints on ultra heavy dark matter from the LUX-ZEPLIN (LZ) experiment

Despite the bulk of gravitational evidence, little is known about the nature of dark matter (DM). New particles were invoked to explain this puzzle, with the weakly interacting massive particle (WIMP) and the QCD axion being the two most popular candidates. However, searches for these particles have so far come back empty-handed. Alternative dark matter candidates have been proposed, in particular, Ultra Heavy Dark Matter (UHDM), formed by composite blobs of dark matter particles held together by a hidden sector force. Following a process akin to Big Bang Nucleosynthesis and assuming a hidden sector force that is strongly self-interacting and long-range, successive dark matter constituents could fuse together in the early universe to form extraordinarily heavy blobs. As opposed to point-like dark matter, UHDM is expected to interact with most of the Standard Model particles it encounters, which would result in a multi-scatter event in a terrestrial experiment. In this talk, I will present a re-analysis of the first science data collected by the LUX-ZEPLIN (LZ) experiment to search for UHDM and show new constraints on the DM-nucleon cross section.

Speaker: Ibles Olcina Samblas

UCLA-DM_2023_IO-final.pdf

Coffe break

SESSION 11: Direct Detection: status of crystalline WIMP detectors (CHAIR: Bernard Sadoulet - Berkeley)

107 Results and perspectives from DAMA/LIBRA

The DAMA/LIBRA–phase2 experiment 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 a signal that meets all the requirements of the model independent Dark Matter annual modulation signature, at high C.L. 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 are outlined.

Speaker: Pierluigi Belli

belli_DM2023_web.pdf

108 The SABRE project

The Sodium-iodide with Active Background REjection (SABRE) project attempts to test the controversial DAMA/LIBRA positive and model-independent dark matter claim by exploiting two nearly twin detectors in the northern hemisphere at LNGS (SABRE-North) and the southern hemisphere at SUPL (SABRE-South). The SABRE two locations represent a unique feature and the possibility of reducing systematic effects due to cosmic rays. Both projects will make use of high radio-purity NaI(Tl) detectors developed in collaboration with industrial partners using the vertical Bridgman method. The initial goal of SABRE was the development of a highly pure NaI powder and use it to make NaI(Tl) crystals. Several crystals made with this new powder have been tested deep underground at LNGS. The results of crystal characterization will be presented in the talk along with the strategy adopted for mass production needed for SABRE-North and SABRE-South. The design of the two projects and ongoing activities for SABRE-North in particular will also be discussed.

Speaker: Aldo Ianni (INFN LNGS)

SABRE-Status-UCLADM2023.pdf

SABRE-Status-UCLADM2023.pptx

109 ANAIS-112: testing the DAMA/LIBRA signal beyond 3 sigma

To the date, the only positive signal of presence of dark matter (DM) in the Milky Way halo by direct observation of its interaction with a detector comes from the DAMA/LIBRA experiment in the Gran Sasso National Laboratory (LNGS). For more than 20 years it has observed an annual modulation in the low energy counting rate compatible with that expected due to the rotation of the Earth around the Sun. For most WIMP candidates this result is incompatible with the negative results of other experiments, remaining as one of the most intriguing puzzles in the field.
The goal of ANAIS-112 is to provide a direct and independent check of the DAMA/LIBRA DM positive result using the same type of detector: NaI(Tl) scintillators. The experiment was installed in August 2017 in the Canfranc Underground Laboratory (LSC) and is taking data since then with excellent performance. The results published so far, corresponding to 1.5 and 3 years of data collection, show no modulation and are incompatible with DAMA/LIBRA for a sensitivity of 2.5-2.7σ C.L. In this talk I will present a reanalysis of the 3 years data using new filtering protocols based on machine learning techniques, which notably increases the experimental sensitivity. New sensitivity prospects and preliminary modulation results will also be presented.

Speaker: Maria Martinez

UCLADM_23_MMartinez.pdf

110 COSINUS - Progressing towards shedding light on the DAMA/LIBRA claim

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“ readout concept. Furthermore we will present on the current status of the experimental setup installation presently ongoing at the Gran Sasso underground lab in Italy.

Speaker: Karoline Julia Schaeffner (Max-Planck Institute for Physics)

COSINUS_UCLA_schaeffner_final.pdf

111 Dark Matter Direct Detection Searches with COSINE Experiment

COSINE-100 is a direct detection dark matter search experiment that uses Thallium-doped Sodium Iodide, NaI(Tl) as its target detector material. The detector has been collecting data since September 2016 with continuous stable operation. It consists of ~106 kg of low background NaI(Tl) detectors submerged in a 2 tons liquid scintillator veto counter. The basic goal of the experiment is to test the annual modulation signal for Dark Matter - NaI(Tl) recoils reported by the DAMA/LIBRA experiment. In this talk, I will summarize the latest analysis results on WIMP and annual modulation search, and prospects for the next phase, COSINE-200. In addition to this, I will cover an approach to adopt the analysis procedure that is as close as possible to the DAMA/LIBRA that results in strong modulation amplitude with an opposite phase.

Speaker: Govinda Adhikari (Yale University)

UCLA_cosine_stattus_govinda.pdf

112 Resolving DAMA

Since the DAMA collaboration first made their claim for detection of dark matter in the late ‘90s, there have been many speculations as to sources of their annual modulation signal. Since then, many of the hypotheses have been ruled out. In addition, direct detection dark matter experiments using various target medium, including those that use the same target of NaI(Tl), have ruled out dark matter as the source of the annual modulation observed in DAMA/NaI and DAMA/LIBRA. I will discuss the status of the ongoing efforts and summarize the status of the field.

Speaker: Reina Maruyama

UCLA_DM2023_Maruyama_fin.pdf

113 Status and prospects of CDEX experiment

CDEX experiment at the China Jinping Underground Laboratory (CJPL) is a germanium detector experiment locate at Sichuan of China, which target for Weakly interacting massive particles (WIMP) dark matter search and neutrinoless double beta decay search. In this report, we will describe current status and future plans of CDEX experiment. In partucular we will present various results based on analysis from 1-kg mass p-type point-contact germanium detector of the CDEX-1B experiment and CDEX-10 experiment. These results include WIMP-nucleus with Migdal effect and WIMP-electrons interactions with earth scattering correction, as well as other analysis from various dark sectors. Efforts ongoing toward to the next phase CDEX-50 for dark matter search and the projected sensitivities will be presented. The upgrades at CJPL-II toward ton scale germanium experiments will be also discussed.

Reference:
H. Jiang, et. al., Phys. Rev. Lett. 120, 241301 (2018).
Z. Z. Liu, et. al., Phys. Rev. Lett. 123, 161301 (2019).
Z. She, et. al., Phys. Rev. Lett. 124, 111301 (2020).
Y. Wang, et. al., Phys. Rev. D 101, 052003 (2020).
Z. Z. Liu, et. al., Phys. Rev. D 105, 052005 (2022).
R. Xu, et. al., Phys. Rev. D 106, 052008 (2022).
Z. Y. Zhang, et. al., Phys. Rev. Lett. 129, 221301 (2022).
W. H. Dai, et. al., Phys. Rev. Lett. 129, 221802 (2022).
X. P. Geng, et. al., arXiv:2210.01604.
Z. H. Zhang, et. al., arXiv:2211.07477.
W. H. Dai, et. al., Phys. Rev. D 106, 032012 (2022)

Speaker: Dr Hau-Bin Li (Institute of Physics, Academia Sinica, Taipei, Taiwan)

CDEX_prospects_DM2023_lihb (1).pdf

12:00 Lunch Break

SESSION 12: Direct Detection: status of sub-GeV DM detection (CHAIR: Maria Martinez - IUCA - Universidad de Zaragoza)

114 The SNOLAB SuperCDMS experiment

The SuperCDMS SNOLAB experiment is a direct dark matter (DM) search experiment under construction at the SNOLAB underground laboratory in Sudbury , Canada. It will focus on the search for low mass DM candidates by employing cryogenic Ge and Si detectors, with expected world-leading sensitivity for particles with masses in the range between 0.5 and 5 GeV/c$^2$. Two types of detectors are employed. The interleaved Z-dependent ionization and phonon (iZIP) detectors, thanks to their background discrimination capability, will be used to push the sensitivity down in cross section. The high voltage (HV) detectors, in which a voltage bias is applied to amplify the ionization signal in the form of phonons, are utilized to explore new regions of mass thanks to their lower energy threshold. In this talk I will present the current status of the experiment installation discussing its discovery potential.

Speaker: Emanuele Michielin

michielin_UCLA_V4.pdf

115 Sub-GeV Dark Matter Searches with EDELWEISS and CRYOSEL

The EDELWEISS collaboration searches for light Dark Matter (DM) particles using germanium detectors equipped with a charge and phonon signal readout.
To circumvent the problem of the large background of events with no ionisation signal ("Heat-Only" events) that limit the sensitivity of our detectors equipped with Ge-NTD sensors, the collaboration has tested the use of NbSi Transition Edge Sensors (TES). The observed HO background reduction in a 200g detector equipped with a TES readout and operated underground in the Laboratoire Souterrain de Modane (LSM) has yielded a sensivity to DM masses down to 32 MeV/c² and cross sections down to 10-29 cm². Further improvements have been more recently obtained by exploting the phonon yield from the Neganov-Luke-Trofimov effect to better resolve electron recoils from HO events. These results pave the way for a new detector design, named CRYOSEL, that is being optimized for such a discrimination.

Speaker: Jules GASCON

EdelweissCRYOSEL-UCLA2023_c.pdf

116 Status and first results of the DAMIC-M experiment

The DAMIC-M experiment will search for dark matter particles via direct detection using thick, fully depleted silicon charge-coupled devices (CCDs) with a target exposure of 1 kg-year. The CCDs have been enhanced with the skipper readout technology which allows for single electron resolution through multiple non-destructive measurements of the individual pixel charge, lowering the detection threshold to the eV-scale. This experiment aims to significantly advance the exploration of the dark matter particle hypothesis, particularly for leptophilic candidates of the hidden sector with mass in the sub-GeV range.
The Low Background Chamber (LBC) prototype, containing 20g of low background Skipper CCDs, was installed at the Laboratoire Souterrain de Modane at the end of 2021 and is currently in operation. The main objective is the demonstration of the feasibility of skipper CCD technology in a low-background environment and the evaluation of the experimental sensitivity for light dark matter searches. This presentation will discuss the status and the first results of this experiment.

Speaker: Dr Jean-Philippe Zopounidis (Sorbonne University / LPNHE)

UCLA_2023_JPZopounidis.pdf

117 Sub-GeV dark matter searches with SENSEI

SENSEI (Sub-Electron Noise Skipper Experimental Instrument) is a direct detection dark matter experiment with detectors operating at Fermilab and at the SNOLAB underground facility. The experiment consists of silicon Skipper-CCD sensors that make multiple non-destructive measurements of the charge contained in each of millions of pixels, reducing the readout noise to a level that allows for resolution of single electrons. This low energy threshold, along with low rates of events with one, two, three, and four electrons, results in competitive sensitivity for low-mass dark matter candidates that interact with electrons over a wide range of dark matter masses. In this talk we present an overview of the SENSEI experiment, as well as the current status after the successful commissioning of the first batch of science-grade sensors at SNOLAB.

Speaker: Kelly Stifter (Fermilab)

Stifter_SENSEI_UCLADM2023.pdf

118 The Oscura experiment

The electron-counting capability of the skipper-CCD technology is allowing it to lead the search for DM-electron interactions in the low-mass regime with g-size experiments. There are ongoing efforts for developing massive direct DM search experiments with this technology. Oscura, an array of ~20,000 silicon skipper-CCDs (10 kg), is the biggest within them. Its final goal is to have less than one 2e- background events for the full exposure of 30 kg-year. In this talk I will present the current status of the Oscura experiment, the projected sensitivities to different DM models and the future plans.

Speaker: Brenda Cervantes

UCLADM2023_BrendaCervantes_ALL.pdf

119 Probing light Dark Matter with the CRESST-III experiment

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: CaWO$_4$, Al$_2$O$_3$, LiAlO$_2$, and Si. With detection thresholds for nuclear recoils as low as 10 eV, CRESST is extremely suitable in the search for low mass dark matter particles. Most recent CRESST-III results on dark matter search are presented. Observations of the unexplained event population at very low energies (“low energy excess”), which is limiting the sensitivity of many experiments in the low mass region, are also reported. Plans for the CRESST future are presented.

Speaker: Paolo Gorla

UCLA_DM_CRESST_Gorla.pdf

120 Search for Solar Boron-8 neutrino and light dark matter with XENON detectors

The XENON collaboration has developed a series of liquid xenon detectors to lead the search for WIMP dark matter. The tonne-scale liquid xenon detectors (such as XENON1T and XENONnT) are sensitive not only to WIMP dark matter but also to the Solar Boron-8 neutrinos. In this talk, I will describe how to improve the analysis of XENON1T and XENONnT data to enhance their sensitivities to Boron-8 neutrinos and light dark matter. Analysis strategy to lower the energy threshold and suppress new backgrounds will be highlighted. With these efforts, we will show that the detection of Solar Boron-8 neutrinos through their coherent elastic scattering off Xenon target is possible in XENONnT. Results and perspectives of this analysis with XENON1T and XENONnT data will also be presented.

Speaker: Prof. Fei Gao (Tsinghua University)

ucla-dm-2023-cevns-xenon.pdf

121 EXCESSES in low-mass dark matter and CEvNS experiments

In recent years, direct dark matter detection experiments extended the hunt for dark matter to masses well below 1GeV, driven by lowering their thresholds to the scale of few eV. However, with the lower thresholds, the experiments started to observe events above the expected background level. Numerous low-threshold experiments observe suchlike EXCESSES of events, a common feature of the EXCESSES is a steep rise toward low energy. The EXCESSES currently are the main limiting factor for affected low-mass dark matter searches and upcoming CEvNS experiments. To pin down the origin of the EXCESSES, the community exchanged their experimental evidence and expertise in three EXCESS workshops in the last two years. In this contribution, we will report on the significant insights gained on the excess and discuss remaining open questions and further prospects of (the) EXCESS(ES).

Speaker: Florian Reindl (Vienna University of Technology (AT))

Reindl_EXCESS_v4.pdf

SESSION 13: Direct detection: Technical Development-1 (CHAIR: Chamkaur Ghag - University College London)

122 Background Determination for the LUX-ZEPLIN Experiment

LUX-ZEPLIN (LZ) is a direct dark matter detection experiment, primarily designed to search for WIMPs, currently taking data. The detector comprises a position sensitive xenon time projection chamber surrounded by an instrumented xenon “Skin” and liquid scintillator active vetoes. An active mass of 7 tonnes of xenon is used, from which a fiducial region of mass 5.6 tonnes is formed that has minimal gamma-ray and neutron activity. The radiopure environment has been further ensured through an extensive material screening and selection campaign, together with in-house xenon purification. These background mitigation strategies underpin LZ’s unprecedented projected sensitivity to WIMPs. This talk will detail the background model derived for LZ’s first science run, in which new limits on WIMP-nucleon interactions were set, down to a spin-independent cross-section of 6.5 x 10^-48 cm^2 for a mass of 30 GeV/c^2 at 90% confidence level.

Speaker: Amy Cottle

Cottle_UCLADM.pdf

123 The XENONnT Neutron Veto

The Neutron Veto of the XENONnT experiment is a Gd-loaded water Cherenkov detector designed to recognise the radiogenic neutrons coming from the detector materials, in order to reduce one of the most important Nuclear Recoil backgrounds for the WIMP search in the XENONnT TPC.
The Neutron Veto is instrumented with 120 (8" Hamamatsu R5912) photomultiplier tubes, featuring high-QE and low-radioactivity, installed inside a high light-collection volume delimited by ePTFE reflector panels around the cryostat.
In this talk we will describe the Neutron Veto performances in the first XENONnT Science Run, where the Veto has been operated with demineralised water.
We will also present the systems for Gd-doping of water in the next phase, as the Gd-Water dissolution and purification plant.

Speaker: Marco Selvi (INFN Bologna)

XENONnT-nVeto-UCLADM-2023-Selvi.pdf

124 Radon mitigation strategies for current and future liquid xenon detectors

Dual-phase liquid xenon time projection chambers (TPCs) are a compelling technology for the detection of rare events such as the interaction of dark matter particles. A dominant background is induced by the radioactive noble gas ²²²Rn, which emanates from material surfaces and distributes homogeneously throughout the detection volume. This problem is usually addressed by a stringent material pre-selection in combination with active radon removal techniques. Both methods have been successfully applied in the XENONnT experiment, which recently achieved an unprecedented low radon concentration of less than 1µBq/kg.
Future liquid xenon detectors, like Darwin/XLZD and nEXO, require a further reduction of their ²²²Rn concentration. To reach this goal, the established mitigation methods need to be complemented by novel radon prevention techniques. This contribution will discuss the feasibility to employ surface coatings as barriers against radon emanation. Different coating techniques have been evaluated, with a focus on the electrodeposition of copper. A very promising radon suppression of three orders of magnitude has been achieved using a custom-made stainless steel radon source. Possible applications and future challenges of this technique will be discussed.

Speaker: Florian Jörg (Max-Planck-Institut für Kernphysik, Heidelberg)

2023_ucla_dm_joerg_small.pdf

125 From Photoelectrons to Bytes in DarkSide-20k

Darkside-20k is a planned experiment at LNGS in Italy, supported by the Global Argon Dark Matter Collaboration. Darkside-20k is a dual phase liquid argon TPC, readout by SiPM-based cryogenic photosensors and designed to perform direct detection of Weakly Interacting Massive Particles (with a mass up to the TeV$/$c$^2$ range). The 20-tonne (fiducial mass) of Argon from an underground source is surrounded by an active neutron veto detector, based on a Gd-loaded acrylic shell. The scintillation light is collected at the bottom and the top planes of the TPC, as well as by the veto photodetectors. This talk focuses on the light detection technology and the trigger-less data acquisition system. The photosensor readout unit is a $25$ cm$^2$ array of SiPMs, called Photo Detector Module, or PDM. The PDM’s performances will be outlined, including an overview of the characterization of the unit's signal-to-noise ratio and time resolution. The PDM signals are digitized and processed online in a dedicated computing farm. The implementation of the data acquisition will be presented, along with the preliminary performance estimate.

Speaker: Andrea Capra (TRIUMF (CA))

A_Capra_PE_DAQ_DS20k_UCLA_DM_2023.pdf

126 First measurement of discrimination between helium and electron recoils in liquid xenon as a means for detecting sub-GeV dark matter (HydroX)

HydroX is a proposal to improve the sensitivity of liquid xenon TPCs to O(1) GeV particle dark matter by doping a light element such as hydrogen or helium into the liquid. However, no data exist on the signal yields and discrimination for light elements recoiling in liquid xenon. This talk provides updates on the status of HydroX efforts and presents a first measurement of the discrimination between recoiling helium nuclei and electron recoils in liquid xenon. The electron and photon signals from helium nuclear recoils created using a novel, low-energy alpha particle source are simultaneously measured in a cm-scale, dual-phase xenon TPC and compared to those from electron recoils produced via Compton scattering. The excellent discrimination observed between these two populations offers significant promise for HydroX.

Speaker: Scott Haselschwardt

haselschwardt_ucla_2023.pdf

127 Superconducting Nanowire Single Photon Detectors for Dark Matter Detection

We will discuss the latest advances in superconducting nanowire single photon detectors, which are the highest performing detectors for time-resolved single photon counting from the UV to the longwave infrared. We will discuss recent progress in scaling active area and dark counts to enable new dark matter search concepts, and recent progress in reducing the energy threshold of the detectors below 100 meV. We will discuss the prospects for using this new technology for a variety of new experimental concepts in low-mass dark matter detection.

Speaker: Matthew Shaw (Jet Propulsion Laboratory)

UCLA Dark Matter 31 March 2023.pdf

Coffee Break

SESSION 14: Direct detection: Technical Development-2 (CHAIR: Rafael Lang - Purdue University)

128 Migdal Search in LUX-ZEPLIN Dark Matter Experiment

When a xenon atom’s nucleus recoils from a dark matter particle or any other incident radiation, the atom’s electron cloud is expected to fall behind, resulting in possible ionization and excitation. This phenomenon is called the Migdal effect and is attracting attention as it can improve the sensitivity of direct dark matter search in the sub-GeV/c$^2$ regime. In a liquid xenon detector like LUX-ZEPLIN Experiment, it is expected that the inelastic component from the Migdal effect enhances the nuclear recoil signals. To search for such enhancement, monoenergetic 2.45 MeV neutrons from Adelphi Technologies’ DD 109 neutron generator were used to make high-rate nuclear recoil events. In this talk, I will discuss our efforts to confirm and calibrate the Migdal effect using neutron-xenon scattering data from the LUX-ZEPLIN Experiment, focusing on the Migdal effects with electrons emitted from L and M shells.

Speaker: Jeanne Bang (Brown University)

UCLA 2023 Dark Matter - Migdal Search in LZ - Jeanne Bang.pdf

129 Experimental result on measuring the Migdal effect with neutron-induced nuclear recoils at the keV level in liquid xenon

The sensitivity of current dark matter experiments to sub-GeV mass dark matter candidates can be substantially improved by the Migdal effect, which predicts a finite probability for a nuclear recoil interaction to be accompanied by atomic excitation or ionization. The additional Migdal energy deposition enhances observable signals in experiments that measure scintillation and ionizations, and can elevate a fraction of nuclear recoil interactions below the detector thresholds to above thresholds. We carried out a direct search for the Migdal effect in liquid xenon using $\mathcal{O}(10^5)$ xenon recoils in the keV region produced by scatters of 14.1MeV neutrons in a compact xenon time projection chamber. This data is predicted to contain thousands of Migdal interactions, of which a few hundred should produce observable signatures. We search for these signals in a way that is minimally impacted by uncertainties in nuclear cross section data or inaccuracies from modeling the detector response to nuclear recoils. The result of this search and the implications for dark matter experiments will be discussed.

Prepared by LLNL under Contract DE-AC52-07NA27344 with a LLNL IM release number LLNL-ABS-843773.

Speaker: Dr Jingke Xu (Lawrence Livermore National Laboratory)

UCLADM2023_MigdalXu.pdf

130 Phonon-mediated kinetic inductance detectors for sub-GeV dark matter searches

Kinetic inductance detectors (KIDs) as low mass dark matter detectors are interesting for two reasons: 1) their massive multiplexability and concomitant position resolution enable NR/ER discrimination down to 500eV recoil energy, allowing for neutrino-limited NRDM searches from 0.5GeV-5GeV, and 2) a variety of RF-based and KID-specific improvements chart an attainable path forward to sub-eV recoil energy resolutions. To date, a prototype 1 gram 20-KID device has demonstrated <1mm position resolution and 0.55keV resolution at 30keV. We report on the progress of two different KID architectures that highlight our two main thrusts of demonstrating multiplexability and sub-eV resolutions: 1) a 9 gram 80-KID device has shown scalability issues that we believe can be solved with improved RF engineering, and 2) a 1 gram single KID device has shown an inferred baseline energy resolution of 20eV, with 5eV resolution immediately possible with minor modifications.

Speaker: Osmond Wen

2023_UCLA_DM.pdf

131 Results from the KDK experiement

Potassium-40 (40K) is a naturally-occurring radioactive isotope. It is a background in rare-event searches, plays a role in geochronology, and has a nuclear structure of interest to theorists. This radionuclide decays mainly by beta emission to calcium, and by electron-capture to an excited state of argon. The electron-capture decay of 40K directly to the ground state of argon has never been measured, and predicted intensities are highly variable (0–0.22%). This poorly understood intensity may impact the interpretation of the DAMA claim of dark matter discovery by constraining the signal modulation fraction [1]. The KDK (potassium decay) experiment has carried out the first measurement of this electron-capture branch, using a novel setup at Oak Ridge National Labs [2]. KDK deployed a very sensitive inner detector to trigger on the ~keV radiation emitted by both forms of electron capture, surrounded by a very efficient veto to distinguish between the decays to ground state and those to the excited state. We present result of the experiment [3].

[1] Pradler et al, Physics Letters B 720 (2013) 399–404, http://dx.doi.org/10.1016/j.physletb.2013.02.033

[2] Stukel et al, Nuclear Inst. and Methods in Physics Research, A 1012 (2021) 165593, https://doi.org/10.1016/j.nima.2021.165593

[3] Stukel et al, https://doi.org/10.48550/arXiv.2211.10319

Speaker: Philippe Di Stefano

DiStefano_Session14_KDK_UCLA_2023_03_med.pdf

132 The innovative Underground Argon Project: the path from procurement to purification for search of Dark Matter

The search for Dark Matter is one of the most fascinating themes of modern physics and astrophysics, but also one of the most difficult to study. The innovative Underground Argon Project (UAr) is part of this context and a fundamental pillar of the Argon Dark Matter search program, led by the Global Argon Dark Matter Collaboration. The aims of the UAr project is to achieve the procurement of large amounts of low-radioactive UAr as detector target; currently three plants are in development to ensure this:
- Extraction of argon with a naturally low concentration of radioactivity 39Ar from an underground source (CO2 wells) will be carried out at the Urania plant, in Cortez, CO (US). This is the same source of UAr used for the DarkSide-50 detector.
- UAr will be further chemically purified to detector-grade argon in the Aria facility, in a mine at Carbosulcis Spa, Sardinia (Italy); Aria will have a 350 m cryogenic distillation column, which is longer than the Eiffel tower and made up of about 3000 distillation stages.
- Assessing the ultra-low 39Ar content of the UAr is crucial for the GADMC projects. This is the goal of the DArT detector, using a small chamber placed at the center of the ArDM detector in the Canfranc Underground Laboratory (LSC) in Spain. It aims to measure 39Ar below the mBq/kg level with 10% precision in one week of run.
In this talk, we will discuss the status of UAr Project, the challenge for its production through the 3 plants above mentioned, their latest results, and the growing interest in the use of ultra-pure UAr as it has potential broader applications outside the GADMC, for measuring coherent neutrino scattering, environmental assay, neutrinoless 2β decay, and large DUNE-like detectors and also outside the astro-particle physic for application in the field of the medical physics (new technology for PET).

Speaker: Federico Gabriele (Universita e INFN, Cagliari (IT))

UAr Project_FG_UCLA DM 23 (1).pdf

133 A crystalline xenon TPC to reach the neutrino detection limit

We are developing a dual-phase crystalline/vapor xenon time projection chamber (TPC) as a potential upgrade path for the LZ or XENON dark matter search experiments, after they finish their current experimental operations. We expect it to enable full exclusion or tagging of the dominant radon-chain backgrounds in these instruments, while maintaining all of the known instrumental benefits and performance of a liquid xenon TPC. In this way, it could enable the current O(10) tonne experiments to reach the neutrino detection limit in <20 years. This talk will present recent results of the instrumental performance as well as a first demonstration of the radon exclusion power of crystalline xenon with respect to liquid xenon.

Speaker: Hao Chen

crystal_xenon_ucla.pdf

134 Update from the Scintillating Bubble Chamber (SBC) Collaboration

Liquid-noble bubble chambers provide a unique opportunity to extend electron/nuclear-recoil discrimination to the O(100)-eV thresholds needed for a GeV-scale dark matter search, while maintaining scalability to the ~ton-year exposures needed to explore the solar neutrino CEvNS fog. I will review what we currently know about the low-threshold performance of these devices and give a status update on SBC-LAr10: a 10-kg argon bubble chamber at Fermilab, built by the SBC Collaboration, that aims to calibrate the nuclear recoil detection threshold of the technique with 10-eV resolution at a target 100-eV threshold. I will also describe progress towards the SBC Collaboration’s first dark matter search, featuring a low-background but functionally identical clone of SBC-LAr10.

Speaker: Prof. Eric Dahl

Dahl-SBC-UCLADM2023.pdf

135 A Strategy for Low-Mass Dark Matter Searches with Cryogenic Detectors in the SuperCDMS SNOLAB Facility

The SuperCDMS Collaboration is currently building SuperCDMS SNOLAB, an experiment designed to search for nucleon-coupled dark matter in the 0.5-5 GeV/c$^2$ mass range. Looking to the future, the Collaboration has developed a set of experience-based upgrade scenarios, as well as novel directions, to extend the search for dark matter using the SuperCDMS technology in the SNOLAB facility. The experienced-based scenarios are forecasted to probe many square decades of unexplored dark matter parameter space below 5 GeV/c$^2$, covering over 6 decades in mass: 1-100 eV for dark photons and axion-like particles,1–100 MeV/c$^2$ for dark-photon-coupled light dark matter, and 0.05–5 GeV/c$^2$ for nucleon-coupled dark matter. They will reach the nucleon-coupled neutrino fog in the 0.5–5 GeV/c$^2$ mass range, and they will test a variety of benchmark models and sharp targets for electron-coupled dark matter. These upgrade scenarios rely mainly on dramatic improvements in detector performance based on demonstrated scaling laws and reasonable extrapolations of current performance, with no need for significant reductions in background levels beyond current expectations for SuperCDMS SNOLAB. The novel directions involve greater departures from current SuperCDMS technology but promise even greater reach in the long run. We describe these upgrade plans and their expected sensitivity.

Speaker: Sunil Golwala

230331DM2023GolwalaSuperCDMSFuture_v2_Web.pdf

SESSION 15- Directional Direct Detection (CHAIR: Philippe Di Stefano - Queen's University)

136 Directional Dark Matter Detection

A directional nuclear recoil detector with sufficient target mass could be used to observe and distinguish different neutrino sources, to search for dark matter in the presence of irreducible background, including neutrinos, and to demonstrate the cosmological origin of a dark matter signal. I will review detector R&D efforts and experiments aimed at dark matter detection with directional sensitivity, and the so-called CYGNUS proposal to build large scale directional detectors. I will focus on gas-based efforts based on the concept of recoil imaging, i.e., reconstructing the detailed topology of nuclear recoils. If time allows, I will also comment briefly on broader impacts and other applications of the detectors being developed.

Speaker: Sven Vahsen (University of Hawaii (US))

Snowmass_CYGNUS_UCLA_DM_2023_final.pdf

137 Directional dark matter detection in diamond: principles and experimental progress

The next generation of weakly interacting massive particle (WIMP) dark matter (DM) detectors will be sensitive to coherent scattering of solar neutrinos from target nuclei, demanding an efficient background-signal discrimination tool. A directional detector would enable detection of WIMP DM below the "neutrino floor", otherwise an irreducible background. Diamond has been proposed as a next-generation DM detector because of its sensitivity to low-mass WIMP candidates, as well as its excellent semiconductor properties, making it a suitable target for sub-GeV DM detection. We are developing complementary methods for nuclear recoil directionality readout in diamond. WIMP- and neutrino-induced nuclear recoils would leave a sub-micron track of lattice damage, constituting a durable signal for the incoming particle's direction. Spectroscopy of quantum defects such as nitrogen-vacancy (NV) centers allows detection of crystal damage via the strain induced in the crystal lattice, while methods such as x-ray diffraction microscopy allow nanoscale mapping of crystal structure. An alternative method would be to detect the NV centers induced by the WIMP impact in a low-NV-density sample. We present the proposed directional detection principle as well as an overview of recent experimental results.

Speaker: Reza Ebadi

20230331 UCLADM.pdf

19:35 Dinner on your own (explore Westwood area)

Saturday, 1 April

Morning Coffee

SESSION 16: Direct detection: New Concepts (CHAIR: Alvine Kamaha -UCLA)

138 The Snowball Chamber: Supercooled Water for Dark Matter, Neutrinos, and General Particle Detection

The snowball chamber is analogous to the bubble and cloud chambers in that it relies on a phase transition, but it is new to high-energy particle physics. The concept of the snowball chamber relies on supercooled water (or a noble element, for scintillation for energy reconstruction), which can remain metastable for long time periods in a sufficiently clean and smooth container (on the level of the critical radius for nucleation). The results gleaned from the first prototype setup (20 grams) will be reviewed, as well as plans for the future, with an eye to future deployment of a larger (kg-scale) device underground for direct detection of dark matter WIMPs, with a special focus on low-mass (GeV-scale) WIMPs, capitalizing on the presence of H, which could potentially also lead to world-leading sensitivity to spin-dependent-proton interactions for O(1 GeV/c^2)-mass WIMPs and CEvNS. Supercooled water also has the potential advantage of a sub-keV energy threshold for nuclear recoils, but this remains an atmospheric chemistry prediction that must be verified by careful measurements.

Speaker: Matthew Szydagis

snowball_UCLA_MSZYDAGIS.key

snowball_UCLA_MSZYDAGIS.pdf

139 Mineral Detectors for Neutrinos and Dark Matter

Minerals have been used as nuclear track detectors for more than 50 years - nuclear recoils leave latent damage in the crystal structure. In the past years, there has been much interest in fundamental physics applications for such detectors, not least because of advances in microscopy techniques that have revolutionized our abilities to image defects at the nm scale. In this talk, I will discuss a range of proposed applications of mineral detectors, in particular "paleo-detector" searches for Dark Matter and astrophysical neutrinos: Leveraging the 100 Myr - 1 Gyr exposure times natural minerals on Earth provide, one could not only measure such sources of nuclear recoils with unprecedented exposure, but also learn about their properties, for example, the distribution of Dark Matter in our Galaxy, the evolution of our Sun, or the star formation history of the Milky Way. Research groups in America, Asia, and Europe are pursuing feasibility studies of mineral detectors for neutrinos and Dark Matter, and I will also briefly report on the status and plans of these studies.

Speaker: Sebastian Baum (Stanford University)

Baum_UCLADM.pdf

140 The NOA Facility @ LNGS

Nuova Officina Assergi (NOA) is a Clean Room (CR) - classification ISO6 according to the ISO 14644-1 standard, intended for the construction and assembly of advanced electronic devices. This facility arises as a fundamental part of the Dark side-20K project and it has been realised thanks to two Italian government fundings called “Piano Operativo Nazionale 2014-2020” (PON) and “Programma di Sviluppo RESTART, Delibera CIPE 49/16” and through an agreement between LNGS, Abruzzo Region and Comune dell’Aquila in the field of scientific research. The scope of the NOA clean room is to realise and guarantee two experimental areas and volumes suitable both to produce electronic devices and to operate with big set-up installation for low background detectors. This will be the LNGS facility and once DarkSide assembly is complete it would be open to other activities.
The largest "area" (called CR3, about 350 m2) is devoted to the assembly of the so called “Silicon Photo-Multipliers” (SiPM), which will be used as innovative experimental electronic devices employed in cryogenic conditions as main detector units in the core of Dark Side-20k experiment. The second "area" (called CR2, about 70 m2) will be dedicated to the handling, cleaning and final set-up of big components (the TPC in the DarkSide case) before delivering it underground for the final assembling in the detector. For such reason, the CR has been built using only materials selected for their reduced radon gas emanation; moreover, the air ventilation system has been designed to be coupled with a “Radon abatement system” (of future installation) which will provide air with a reduced Rn concentration for the CR air-supply. These two main features, together with other technical details defined during the CR construction, make NOA a “Rn free” clean room (the expected Rn concentration in air will be lowered by a factor 100, at least).

Speaker: Roberto Tartaglia

zzzzz-CR-NOA-UCLA-DM-230402-Tartaglia-rt25.pdf

SESSION 17: Direct detection: Ultra-Light DM (Axions, ALPs, WISPs) searches-1 (CHAIR: Reina Maruyama -Yale University)

141 An overview of Axion Dark Matter eXperiment: current status and future plans

QCD axion is a well-motivated dark matter candidate which is capable of solving the strong CP problem and explaining the abundance of dark matter at the same time. Axion Dark Matter eXperiment (ADMX) searches for conversions of QCD axions into microwave photons with high-Q tunable resonators running in a strong magnetic field. In the current ADMX Gen 2 phase, thanks to an ultra-low-noise amplifier chain, we have reached the sensitivities for both benchmark models, Kim-Shifman-Vainshtein-Zakharov (KSVZ) and Dine-Fischler-Srednicki-Zhitnitsky (DFSZ), in the golden micro-eV axion mass region. In this talk, I will give an overview of the latest status of the most recent round of data taking, current R&D efforts and future plans.

Speaker: Dan Zhang (University of Washington)

UCLADarkMatter.pdf

142 Low Mass Axion Searches from ABRACADABRA Results to the DMRadio Program

This talk will review the results from ABRACADABRA-10 cm, the status of the DMRadio suite of experiments including DMRadio-50L and DMRadio-m$^3$, and the plans for a next-generation GUT-scale-sensitive experiment, DMRadio-GUT. These experiments search for the coupling of axionic dark matter to electromagnetism at masses below 1 $\mu$eV. Axions at these lower mass ranges can naturally be produced in the measured dark matter abundance if Peccei-Quinn symmetry breaking occurs prior to inflation. A particularly well motivated mass range is from 1-100 neV, which corresponds to PQ symmetry breaking near the Grand Unified Theory (GUT) scale. At these lower frequencies, the Compton wavelength is typically larger than the experimental dimension, so the resonators used are similar to lumped-element resonators in which the resonance frequency is not intrinsically linked to the length scale of the detector.

Speaker: Maria Simanovskaia (Stanford University)

DMRadio and ABRA (2).pdf

143 Searching for axion-like dark matter with precision NMR: the Cosmic Axion Spin Precession Experiments

The dark matter puzzle is one of the most important open problems in modern physics. The axion is a compelling dark matter candidate, since it resolves the strong-CP problem of quantum chromodynamics. I will focus on the Cosmic Axion Spin Precession Experiments (CASPEr-electric, CASPEr-gradient) that use nuclear magnetic resonance to search for the EDM and the gradient interactions of axion-like dark matter. Recent prototype CASPEr experiments have achieved design sensitivity in the nano-electronvolt mass range. We are now developing the next-generation searches, with the goal of achieving, and possibly circumventing, the quantum limits on their sensitivity. Our objective is to develop the experimental search that is sensitive to the QCD axion dark matter over a broad range of masses.

Speaker: Alexander Sushkov

2023-03-31 TALK UCLA CASPEr.pdf

2023-03-31 TALK UCLA CASPEr.pptx

144 Dark Matter Axion Search Using 18T High Temperature Superconducting Magnet

We report details on the axion dark matter search experiment that uses the new technologies of a high-temperature superconducting (HTS) magnet and a Josephson parametric converter (JPC). An 18 T HTS solenoid magnet is developed for this experiment. The JPC is used as the first stage amplifier to achieve a near quantum-limited low-noise condition. A first dark-matter axion search was performed with the 18 T axion haloscope [Y. Lee et al., Phys. Rev. Lett. 128, 241805 (2022)]. The scan frequency range is from 4.7789 GHz to 4.8094 GHz (30.5 MHz range). Our results set the best limit of the axion-photon-photon coupling in the axion mass range of 19.764--19.890 micro-eV. We will discuss the details of the 18T haloscope experiment and its results.
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Speaker: Prof. JONGHEE YOO (Seoul National University)

Yoo2023UCLADM.pdf

145 MADMAX: post-inflationary axion dark matter search

Latest lattice-QCD simulations predict dark matter axions with a mass around 100 μeV if the Peccei-Quinn symmetry was broken after cosmic inflation. This mass range, however, is hardly explored by the current experiments. This talk will introduce a novel traveling-wave-based detector, the dielectric haloscope, to increase sensitivity to the suggested mass range. The MADMAX collaboration aims to realize the novel concept. I will report the status of the MADMAX experiment, with a special focus on the hidden-photon search using a proof-of-principle dielectric haloscope.

Speaker: Chang Lee (Max Planck Society (DE))

UCLA_DM_2023.pdf

09:30 Coffee Break

SESSION 18: Direct detection: Light DM & Ultra-Light DM (Axions, ALPs, WISPs) searches-2 (CHAIR: Sebastian Baum- Stanford University)

146 The ORGAN Experiment: Results, Status, and Future Plans

We present the current status and future plans of the various experiments within The Oscillating Resonant Group AxioN (ORGAN) Collaboration, which develops microwave cavity axion haloscopes. ORGAN is a collaboration of various nodes of the ARC Centres of Excellence for Engineered Quantum Systems, and Dark Matter Particle Physics, and is primarily hosted at the University of Western Australia.

The ORGAN Experiment is a high mass haloscope (~60-200 micro-eV) broken down into various phases, having commenced in 2021, and running until 2026 [1]. Phase 1a recently concluded, excluding ALP Cogenesis models of dark matter in the mass range of 63 – 67 micro-eV [2].

Phase 1b is currently in commissioning, planned to commence in early 2023, and Phase 2 is in research and development. Active avenues of research for ORGAN include novel high frequency cavity design [3,4], superconducting materials, and single photon counting.

ORGAN-Q is a pathfinder experiment (~25 micro-eV), designed as a testbed for various techniques to be integrated into the main ORGAN Experiment in future phases, such as quantum-limited amplification, and other improvements.

Various other, spin-off and related experiments are also in development. We will summarize each experiment in terms of the relevant experimental details, current status, run plans, and projected reach.

1. Ben T. McAllister, Graeme Flower, Eugene N. Ivanov, Maxim Goryachev, Jeremy Bourhill, Michael E. Tobar, ‘The ORGAN experiment: An axion haloscope above 15 GHz’, Physics of the Dark Universe 18, 67-72
2. Aaron P. Quiskamp, Ben T. McAllister, Paul Altin, Eugene N. Ivanov, Maxim Goryachev, Michael E. Tobar, ‘Direct Search for Dark Matter Axions Excluding ALP Cogenesis in the 63-67 micro-eV Range, with The ORGAN Experiment’, Science Advances (accepted, in production), arXiv:2203.12152
3. Ben T. McAllister, Graeme Flower, Lucas E. Tobar, and Michael E. Tobar, ‘Tunable Supermode Dielectric Resonators for Axion Dark-Matter Haloscopes, Phys. Rev. Applied 9, 014028
4. Aaron P. Quiskamp, Ben T. McAllister, Gray Rybka, and Michael E. Tobar, ‘Dielectric-Boosted Sensitivity to Cylindrical Azimuthally Varying Transverse-Magnetic Resonant Modes in an Axion Haloscope’, Phys. Rev. Applied 14, 044051

Speaker: Ben McAllister

McAllister_UCLA_DM.pdf

147 Searching for axions with metamaterials: the ALPHA detector

Among the theoretical particles that could explain dark matter, axions make an ideal candidate. They can be produced in the early Universe and make up the observed abundances, permeating the universe as an invisible wave. In recent years, the efforts to build a kind of radio that would tune to this unique frequency has intensified, with conventional techniques failing to look for high frequencies. By arranging materials macroscopically in a clever fashion (so called metamaterials) to engineer a custom plasma, the Axion Longitudinal Plasma Haloscope (ALPHA) will allow for some of the best motivated and most difficult frequencies to be scanned, potentially revealing the nature of dark matter. The talk reviews the most recent progress of the consortium as well as providing an overview of potential search strategies.

Speaker: Andrea Gallo Rosso

Gallo Rosso UCLA DM 2023.pdf

148 Probing the axion-photon coupling with the QUAX haloscope

The QUest for Axion (QUAX) is a direct-detection CDM axion search which reaches the sensitivity necessary for the detection of galactic QCD-axion in the range of frequency 8.5-11 GHz. The QUAX collaboration is operating two haloscopes, located at LNL- and LNF-INFN laboratories in Italy, that work in synergy and operate in different mass ranges. In this talk we will report about results obtained at the LNL laboratories, using a high quality factor dielectric cavity cooled at less than 100 mK inside a dilution refrigerator equipped with a 8 T magnet. With a TWPA-based amplification chain for cavity signal readout, resulting in a system noise temperature of 2 K, data have been acquired and analyzed to probe for KSVZ axions in a small range around a frequency of 10.3 GHz. 


We will also report about R&D activity aimed at increasing the scanning speed with application of transmon-based single microwave photon detectors (SMPDs) for cavity readout. The prototype haloscope we developed is based on a cylindrical copper cavity sputtered with NbTi, resonant at 7.3 GHz frequency, and cooled at mK temperatures inside a dilution refrigerator equipped with a SC magnet. Results obtained employing a moderate magnetic field will be described.

Speaker: Dr Antonios Gardikiotis (Universität Hamburg, Hamburg, Germany)

UCLA_2023.pdf

149 The Windchime Project

The Windchime Project seeks to exploit advances in quantum sensing technologies in order to search for dark matter in the laboratory, based on its gravitational interaction alone. The Planck mass (~10^19 GeV or 20 micrograms) is a particularly well-motivated mass range to search for dark matter. At this mass, the dark matter flux at Earth is still large enough to be experimentally accessible, while at the same time, tracks left by the gravitational pull from Planck-mass particles could be detected with a sensitive array of accelerometers. This talk will present the basic idea together with predicted sensitivities for accelerometers with quantum-enhanced readout. In addition to the high-mass range near the Planck mass, the Windchime array of accelerometers is also sensitive to a variety of ultralight dark matter candidates. The status of the project with preliminary results from a number of prototype setups will be presented.

Speaker: Rafael Lang

rafael_windchime_pdf.pdf

150 The TESSERACT Project

The TESSERACT project will search for sub-GeV dark matter via multiple complementary advanced, ultra-sensitive phonon detectors, sensitive to nuclear-type, electron-type, and dark photon-type DM interactions, using targets of liquid helium (HeRALD) and the polar crystals GaAs and Sapphire (SPICE). Those detectors will share identical readout and experimental settings. Besides maximizing sensitivity, this multi-target approach also allows us to identify and discriminate against novel instrumental and physical backgrounds. The experiment is presently in a period of targeted R&D with the first physics results based on demonstrator setups to be expected this year. We will present the status of the experiments and sensors, expected sensitivities, and possible ways to achieve sub-MeV dark matter mass sensitivity.

Speaker: Bjoern Penning

Tesseract UCLA 2023 Penning.pdf

151 Progress Toward a Superfluid 4He Detector for Light Dark Matter (HeRALD)

We report recent progress toward using superfluid 4He for nuclear recoil direct detection, as part of the overall TESSERACT pre-Project R&D effort. The quantum evaporation signal pathway allows both a low threshold and the possibility of rejecting the primary low-energy background (heat-only events in the calorimetry itself) through multi-channel coincidence. We have recently demonstrated the key technology of Cesium-based superfluid film-stopping, newly allowing measurements of 4He scintillation and evaporation signal yields at sub-keV energies.

Speaker: Scott Hertel

HeRALD UCLA 2023.pdf

152 Search for dark matter axion with TASEH

TASEH (Taiwan Axion Search Experiment with Haloscope) devotes to search dark matter axions based on a haloscope setup, consisting of a frequency-tunable microwave cavity detector in a strong magnetic field and a readout amplification chain. The TASEH experiment targets axion searches in the mass range of 10–25 μeV, roughly corresponding to the frequency band of 2.5–6 GHz. In this presentation, we will describe its first physics search, which excludes values of the axion-photon coupling constant $|g_{aγγ}| ≳ 8.1 × 10^{−14}$ GeV$^{−1}$, a factor of 11 above the KSVZ benchmark model, in the mass range of 19.4687–19.8436 μeV. We will also illustrate our subsequent efforts on improving the detection sensitivity up to the QCD axion-photon coupling limit, including developing a large-volume conic shell-cavity detector and integrating a quantum-limited Josephson parametric amplifier to the readout chain.

Speaker: Yung-Fu Chen (National Central University)

TASEH status v3.pdf

153 Broadband Reflector Experiment for Axion Detection (BREAD)

We introduce the Broadband Reflector Experiment for Axion Detection (BREAD) conceptual design and science program. This haloscope plans to search for bosonic dark matter across the [10−3, 1] eV ([0.24, 240] THz) mass range. BREAD proposes a cylindrical metal barrel to convert dark matter into photons, which a novel parabolic reflector design focuses onto a photosensor. This unique geometry enables enclosure in standard cryostats and high-field solenoids, overcoming limitations of current dish antennas.

Speaker: Andrew Sonnenschein (Fermilab)

BREAD_UCLA_2023.pdf

BREAD_UCLA_2023.pptx

154 New Results from HAYSTAC’s Phase II Operation with a Squeezed State Receiver

Data from astrophysics and cosmology point to the existence of Cold Dark Matter in the Universe, for which a light axion is a well-motivated candidate. The HAYSTAC Experiment (Haloscope At Yale Sensitive To Axion CDM) is a microwave cavity search for axions with masses above 10 $\mu$eV/c$^2$. HAYSTAC, now in its second iteration, Phase II, employs squeezed state receiver to achieve sub-quantum limited noise. We will report on details of the design and operation of the experiment previously used to search for axions in the mass ranges 16.96–17.12 and 17.14–17.28 $\mu$eV/c$^2$ (4.100–4.140 GHz and 4.145–4.178 GHz) as well as the new results from our search at higher masses between 18.44–18.71 $\mu$eV/c$^2$ (4.459-4.523 GHz). We will also discuss upgrades currently under development for Phase III.

Speaker: Michael Jewell (Yale University)

haystac_jewell_UCLADM_2023_final.pdf

Final Talk

155 FINAL TALK

Speaker: Michael Turner

UCLA DM Turner.pdf

UCLA DM Turner.pptx