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The second iteration of the Magnificent CEvNS workshop, focused on the process of coherent elastic neutrino-nucleus scattering (CEvNS).
Proposed in 1974, but unobserved until 2017, the physics accessible with CEvNS is broad. The goal of Magnificent CEvNS is to bring together a broad community of researchers working either directly or peripherally on CEvNS to foster enriching discussions to help direct the field as it continues to grow, forming and strengthening connections between experimentalists and theorists/phenomenologists.
Magnificent CEvNS 2019 is supported by generous contributions from The CoSMS Institute and Triangle Universities Nuclear Laboratory.
COHERENT Experimental Overview
CsI[Na] effort of the COHERENT collaboration.
One of the signatures of coherent elastic neutrino-nucleus scattering (CEvNS) is the predicted scaling of the cross section with number of neutrons in the recoiling nucleus squared (N$^2$). The COHERENT collaboration was formed to study CEvNS with a variety of targets to test the physics of CEvNS, including the N$^2$ cross section scaling. As part of COHERENT, a segmented ton-scale NaI[Tl] experiment is being prepared for deployment to the Spallation Neutron Source (SNS) to detect CEvNS-induced nuclear recoils. A dual-gain base has been developed to potentially allow a simultaneous measurement of CEvNS on sodium and iodine nuclei as well as charged-current electron neutrino interactions on iodine within the same detector. An overview of the detector will be presented, along with current status and future plans.
The first observation of coherent elastic neutrino-nucleus scattering (CEvNS) was made by the COHERENT collaboration at the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source (SNS) in August 2017 with a 14.6 kg CsI(Na) detector. One of the physics goals of the COHERENT experiment is to test the N$^2$ dependence of the CEvNS cross section predicted in the Standard Model by observing CEvNS in multiple low-threshold detectors. To that end, the $\sim$24 kg CENNS-10 liquid argon detector was deployed at the low-background Neutrino Alley at the SNS. An observation of CEvNS with CENNS-10 would provide a low N measurement to begin to map out the CEvNS cross section. CENNS-10 was deployed in December 2016 for an initial Engineering Run ending in May 2017 and subsequently upgraded for a Production Run beginning in July 2017. In this talk, I will present the latest results from a CEvNS search with the CENNS-10 liquid argon detector.
Neutron stars are cosmic laboratories uniquely poised to answer fundamental questions about the nature of dense neutron-rich matter. However, knowledge of the equation of state of neutron-rich matter is hindered by uncertainties in the neutron distribution of neutron-rich nuclei. Electroweak probes of ground state densities provide a clean and model-independent tool to mitigate these uncertainties. In this presentation I aim to provide compelling connections between nuclear form factors and neutron stars.
CEvNS in effective field theory.
Inelastic neutrino interactions on nuclei.
Assuming light vector mediators, we discuss the effects of CP violation on the coherent elastic neutrino-nucleus scattering (CEvNS) process in the COHERENT sodium-iodine, liquid argon and germanium detectors. We show that in some regions of the parameter space, the presence of a dip in the event rate spectrum can be used to constraint CP violating effects. In other regions, we find that CP violating parameters can mimic the Standard Model CEvNS spectra induced by real parameters. We point out that the interpretation of CEvNS data in terms of a light vector mediator should take into account possible CP violating effects.
Neutrino non-standard interactions and signatures in CEvNS experiments.
I will discuss the usefulness of timing information in the COHERENT experiment in the search for dark matter signals.
We consider a model of light (sub-GeV) dark matter that escapes many
of the bounds placed by current dark matter searches. Such low mass
dark matter candidates, if produced as a thermal relic in the early
universe, must be accompanied by light mediators in order to reproduce
the dark matter abundance observed in the present-day universe. These
light mediators provide new channels for the production and detection
of dark matter at fixed-target neutrino experiments, and proton beam
dumps. Detectors sensitive to neutrinos could detect the resulting
relativistic dark matter beam through neutral-current-like
interactions. Coherent neutrino-nucleus scattering experiments such as
COHERENT and Coherent Captain-Mills could produce these dark matter
candidates through neutral pion decay at a rate similar to that of
neutrinos. Low energy, coherent scattering channels can significantly
enhance the expected dark matter signal beyond that expected at higher
energy fixed-target experiments and provide unique sensitivity to
light dark matter candidates.
We classify new physics signals in coherent elastic neutrino-nucleus scattering (CEvNS) processes induced by B8 solar neutrinos in multi-ton xenon dark matter (DM) detectors. Our analysis focuses on vector and scalar interactions in the effective and light mediator limits after considering the constraints emerging from the recent COHERENT data and neutrino masses. In both cases we identify a region where measurements of the event spectrum alone suffice to establish whether the new physics signal is related with vector or scalar couplings. We identify as well a region where in addition measurements of the recoil spectrum are required so to establish the nature of the new interaction, and categorize the spectral features that enable distinguishing the vector from the scalar case. We demonstrate that measurements of the isospin nature of the new interaction and thereby removal of isospin related degeneracies are possible by combining independent measurements from two different detectors. We also comment on the status of searches for vector and scalar interactions for on-going multi-ton year xenon experiments.
The CONUS experiment is located at the nuclear power plant of Brokdorf, Germany, at 17m distance from the reactor core. It aims at detecting coherent elastic neutrino nucleus scattering with four high-purity point contact Germanium detectors with a noise threshold in the range of 300 eV inside an elaborate shield. Proximity to a reactor core requires an in-depth understanding of the neutron background. The thorough characterization of the background with Bonner sphere measurements and a non-shielded Ge spectrometer will be presented and the successful suppression of all reactor-correlated background contributions within the CONUS shield will be shown. The remaining background contributions are examined with the help of Monte Carlo simulations. The special requirements for a detector close to a nuclear power plant will be discussed and the solutions will be presented. In the talk it will be illustrated how these challenges are met for the CONUS experiment. The long-term performance of the detectors and the latest results will be shown.
The RED-100 is a two-phase emission detector created to investigate coherent elastic neutrino scattering off xenon nuclei. Its active volume has a cylindrical shape with sizes of ~ 40 cm. The total mass of liquid xenon in the detector equals 200 kg. The detector performance provides sensitivity down to a single ionization electron while allows operation at a ground surface environment. In this talk, the current status of the RED-100 detector is presented. During the engineering run, the electron lifetime of several milliseconds was achieved. Technical decisions aimed on reduction of a single electron noise are discussed. Ongoing work on construction of low-background shield is presented. The plan of the experiment at Kalinin Nuclear Power Plant is given.
Progress and plans for the Ricochet experiment.
Last results from the CONNIE collaboration and prospects for next generation of experiments based on Skipper CCD.
The Advanced Imager Technology group at MIT Lincoln Laboratory designs and fabricates detectors and readout circuits for imaging applications in support of National Security and scientific exploration. The group has a long history of supplying silicon charge-coupled devices (CCDs) for the astronomy community, including detectors for the Transiting Exoplanet Survey Satellite (TESS), the Advanced CCD Imaging Spectrometer (ACIS) on Chandra, and the 1.3 gigapixel array for Pan-STARRS at the University of Hawaii. Our CCD imagers are designed in-house, and fabrication is done in the Microelectronics Laboratory (ML), an ISO-9001 certified, 90-nm node semiconductor fabrication facility at the laboratory. In addition to continuously improving the capabilities of our silicon CCDs, our group has recently begun exploring other imager materials and devices, taking advantage of the advanced prototyping capabilities offered by the ML, with the ultimate goal of providing breakthrough imaging devices to enable new scientific observations. In this talk, we outline our progress in two of these new directions: fabricating imaging devices, both CCDs and hybrid active-pixel sensors, with germanium absorbers; and developing superconductor-based detectors for photon and particle detection.
DISTRIBUTION STATEMENT A. Approved for public release: distribution unlimited.
This material is based upon work supported by the Under Secretary of Defense for Research and Engineering under Air Force Contract No. FA8702-15-D-0001. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Under Secretary of Defense for Research and Engineering.
Coherent elastic neutrino-nucleus scattering (CEvNS) is a neutral-current process in which a neutrino scatters off an entire nucleus, depositing a tiny recoil energy. The process is important in core-collapse supernovae and also presents an opportunity for detection of a burst of core-collapse supernova neutrinos in low-threshold detectors designed for dark matter detection. Here we present an ongoing study of prospects for supernova burst detection via CEvNS in existing and future large-scale detectors.
Topics from Tokyo workshop "Dark matter searches in the 2020s - At the crossroads of the WIMP".
Paleo-detectors are a proposed experimental technique in which one would search for traces of recoiling nuclei in ancient minerals. Natural minerals on Earth are as old as $\mathcal{O}(1)\,$Gyr and, in many minerals, the damage tracks left by recoiling nuclei are also preserved for time scales long compared to $1\,$Gyr once created. Thus, even reading out relatively small target samples of order $100\,$g, paleo-detectors would allow one to search for very rare events thanks to the large exposure, $\varepsilon \sim 100\,{\rm g}\,{\rm Gyr} = 10^5\,{\rm t}\,{\rm yr}$. Here, we explore the potential of paleo-detectors to measure nuclear recoils induced by neutrinos from galactic core collapse supernovae. We find that they would not only allow for a direct measurement of the average core collapse supernova rate in the Milky Way, but would also contain information about the time-dependence of the local supernova rate over the past $\sim 1\,$Gyr. Since the supernova rate is thought to be directly proportional to the star formation rate, such a measurement would provide a determination of the local star formation history. We investigate the sensitivity of paleo-detectors to both a smooth time evolution and an enhancement of the core collapse supernova rate on relatively short time scales, as would be expected for a starburst period in the local group.
Plans towards CEvNS observation with LAr detectors at nuclear reactors and possibilities in nuclear safeguards.
Emerging technology and nonproliferation.
Two-phase xenon detectors are being actively developed over the last decade and made substantial improvement of search sensitivity for WIMP dark matter. These detectors, operated in time projection chamber (TPC) mode, strongly suppress the electronic recoil background, making it possible to detect CEvNS of neutrinos at the Spallation Neutron Source (SNS). In addition, two-phase xenon detectors operated in electron counting (EC) mode are sensitive to single-electron signals, making it possible to detect CEvNS from reactor neutrinos and Solar neutrinos. Drawing experience from the XENON10, XENON100 and recent XENON1T experiments, we will discuss the prospects of detecting coherent scattering of neutrinos from SNS, reactors and the Sun using an improved and movable XENON100 detector.
Progress and plans for DARKSIDE and QF measurements in LAr.
Despite evidence from LSND and MiniBooNE for sterile neutrinos at $Δm^2$ = 1 $eV^2$ in electron neutrino appearance experiments, corresponding muon-neutrino disappearance experiments have shown no anomalies. However, these experiments have been performed at a different energy scale compared to LSND and MiniBooNE. Coherent CAPTAIN Mills (CCM) is an experiment at the Lujan Center at LANSCE that uses a 10-ton liquid argon scintillation detector and the coherent elastic neutrino-nucleus scattering (CEνNS) process to measure muon neutrino disappearance at the LSND energy scale. The Lujan Center delivers a 100-kW, 800 MeV, 290 ns wide proton pulse onto a tungsten target at 20 Hz to generate a stopped pion source. The fast pulse is crucial for isolating the 30 MeV monoenergetic muon neutrinos in time and reducing neuron background. In this talk I will describe the CCM detector and show results from our Fall 2018 commissioning run and preliminary results from our Fall 2019 operating run.
Future LAr program in COHERENT.
We will discuss the sensitivity of the COHERENT experiment to test sub-GeV dark matter candidates that may be produced by the SNS and highlight the advantages of using CEvNS detectors for these searches. We also will show strategies within reach of the next generation of detectors that maximize discovery potential for such detectors.
Status and future plans of SuperCDMS.
The LZ dark matter detector is currently under construction at the 4850 level of the Sanford Underground Research Facility (SURF) in Lead, SD. The experiment will contain 7 tonnes of pure xenon in a dual-phase Time Project Chamber (TPC) – a technology that has demonstrated very high sensitivities to hypothetical dark matter interactions. LZ is projected to reach unprecedented sensitivities for WIMP dark matter masses of GeV/c2 to TeV/c2 range. In addition, LZ will also be sensitive to Coherent Elastic Neutrino Nucleus Scattering (CEvNS) from solar neutrinos and supernovae neutrinos as the interactions produce similar nuclear recoil signatures to that of WIMPs. The presence of CEvNS signals in the experiment both provides a direct proof of the detector’s sensitivity and poses an irreducible background in WIMP dark matter searches. I will present an overview of the LZ experiment and its potential in observing CEvNS from high energy neutrino sources.
CYGNUS is a coordinated effort by dark matter direct search groups interested in directional signals, working towards design and build of a global network of directional WIMP experiments able to probe below the neutrino floor. As such, sensitivity is required to detection and measurement of Solar neutrino-nucleus scattering with directional information. The proposed technology is that of low pressure gas time projection chambers. Recent design work on CYGNUS to achieve this will be reviewed including new results on the essential issue of electron background discrimination and intrinsic backgrounds. The potential use of the UK's 1.5 GW Hartlepool reactor for a test run is outlined as well as other efforts in CYGNUS considering the potential for neutrino-nucleus scattering at low energies.
Panel discussion of the Snowmass process, its influence on US high-energy physics funding, and the opportunities for the CE$\nu$NS community to organize itself and participate effectively.
Low-energy nuclear recoil calibrations for SuperCDMS.
NEWS-G (New Experiments With Spheres-Gas) is a rare event search experiment using Spherical Proportional Counters (SPCs) that aims to extend the sensitivity of direct dark matter searches from 0.1 to few GeV mass range. The talk will cover the current status of the experiment and the recent commissioning at LSM.
Primarily designed for the direct detection of dark matter, this technology also has appealing features for Coherent Neutrino-Nucleus Scattering (CE$\nu$NS) studies using nuclear power plants as a neutrino source. For both applications, an important property of the gas to characterize is the ionization yield, or quenching factor, defined as the ratio of the measured energy induced by a nuclear recoil and an electronic recoil of the same energy. Quenching factor measurements in Neon based gas mixtures are being performed at TUNL (Triangle Universities Nuclear Laboratory) using a neutron beam and an array of backing detectors. We will present the set-up and techniques for quenching factor measurements and the last results obtained from measurement campaigns.
The Coherent Elastic Neutrino-Nucleus Scattering has been observed by the
COHERENT collaboration using a 14.6-kg CsI[Na] scintillator at Oak Ridge National Laboratory. This indicates a new way to build a compact neutrino detector and unlocks new channels to test the Standard Model. One challenge is to understand the neutrino-induced low energy nuclear recoils. It is commonly known that the signals from nuclear recoils can be quenched in many types of detectors, resulting in less light or ionization. This phenomenon is referred to as the “quenching factor”. It is defined as the ratio of the signal yield from the nuclear recoils to the signal yield from comparable electron recoils with the same energy. The quenching factor highly depends on the detector materials, so different detectors require their own quenching factor measurements. The next step for the COHERENT experiment is to use different nuclear targets e.g. Ar and Ge. Aside from the COHERENT experiment, many dark matter experiments (CoGeNT, LUX, and etc.) trying to directly detect weakly inter- acting massive particles (WIMPs) also attempt to observe elastic scatterings between WIMPs and nuclei. In this work, we will present the quenching factor measurements for germanium detectors at TUNL in the [0.8,4.9] keVnr range.
Measurement of low-energy nuclear recoil quenching factors in liquid xenon.
Neutrinos at ORNL
Neutrino flux measurement at the SNS with a D2O detector
Neutrino source simulations for the SNS and STS
Various anomalies exist in reactor and accelerator based neutrino experiments. CEvNS experiments are well-positioned to probe possible connections of a short-baseline neutrino oscillation effect to existing anomalies. Considerable complementarity in the flavor and mass space is possible by a combination of experimental efforts.
The MINER collaboration effort to observe CE$\nu$NS.
Abstract.
In experiments aiming on low-interaction energies—exemplified within the low energy neutrinos coherent scatter and quest for low-mass dark matter particles—researchers must understand the underlying noise mechanisms in their detectors. We observed patterns among low-energy detector backgrounds, which invited questions about condensed matter effects in materials under energy flow. Residual radioactivity and cosmogenic radiation lead to slow energy accumulation in detector materials, so we hypothesize that when the relaxation of this energy occurs in a non-steady manner, the avalanche-like events mimic interactions with particles. Though production mechanisms for excitations, their interactions and destructions processes interplay differently across materials, the properties of this dynamic—called self-organized criticality—appear in sectors ranging from particle physics detectors to quantum sensors and qubits, two of which we discuss here. In some cases, these noise mechanisms may be suppressed and mitigated. In this sense, studying the condensed matter effect in particle detectors can provide useful feedback for designing qubits and quantum sensors, yielding an unexpected crosspollination between quantum information and high energy physics. Side-by side comparison of this on a first glance disparate fields allows to understand common problems and see how these fields are merging in studying space microwave background, serches for axions and coherent scatter of low energy neutrinos with low and ultra-low temperature sensors.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344; we acknowledge LDRD grant 17-FS-029. LLNL-ABS-793661-DRAFT.
Potential for CEvNS measurements with cryogenic scintillators.
Neutrino detectors have the proven capability to monitor nuclear reactor power levels and fuel consumption by observing the energy spectrum of neutrinos emitted by the reactor. However, conventional neutrino detection techniques require massive detectors that would be difficult to deploy in the field for nuclear monitoring applications. A new detection method, Coherent Elastic Neutrino-Nucleus Scattering, requires significantly smaller target mass—kilograms instead of kilotons. Therefore, a deployable nuclear monitoring system based on coherent neutrino scattering would have significantly lower size, weight, and power requirements than competing systems based on conventional neutrino detection techniques. Coherent scattering was recently demonstrated for high-energy neutrinos from a spallation source. However, detecting the low-energy neutrinos produced in nuclear reactors will require significant improvements in sensor technology.
The Ricochet collaboration aims to perform the first detection of reactor neutrinos via coherent neutrino scattering. Our approach relies on arrays of TES bolometers specifically optimized to measure extremely low recoil energies in the range of 10-50 eV. In this talk, we will describe our efforts at MIT Lincoln Laboratory to develop circuits for microwave multiplexed readout of these highly-sensitive bolometric detectors.
DISTRIBUTION STATEMENT A. Approved for public release. Distribution is unlimited.
This material is based upon work supported by the Under Secretary of Defense for Research and Engineering under Air Force Contract No. FA8702-15-D-0001. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Under Secretary of Defense for Research and Engineering.
The detection of coherent-neutrino nucleus scattering (CEvNS) opens a new window to study the fundamental properties of neutrinos and to probe physics beyond the Standard Model of Particle Physics. NUCLEUS is a novel cryogenic neutrino experiment at a nuclear power reactor which allows for precision measurements of CEvNS at unprecedentedly low energies. It is based on recently demonstrated ultra-low threshold cryogenic detectors with nuclear-recoil energy thresholds in the 10eV regime. Accessing these energies enables to fully exploit the strongly enhanced cross section of CEvNS which leads to a miniaturization of neutrino detectors. NUCLEUS is fully funded and will be installed at a new experimental site in between the two 4GW reactor cores of the CHOOZ nuclear power plant in France. In this talk I will present recent results from a prototype detector and discuss the experimental strategy as well as the extensive physics program of NUCLEUS.
In this talk, I will show the discovery prospects of Axion-like particle (ALP) at CE$\nu$NS experiments. We consider the ALPs that couples to the standard model through the $a\gamma\gamma$ interaction. The CE$\nu$NS experiments, utilizing reactors and high-intensity proton beam at stopped pion experiments, produce a large number of photons that will be converted to ALPs via the Primakoff process in the target/core. We find that the current facilities at CE$\nu$NS experiments can provide constraints on the unexplored parameter space compared to existing/future ALP experiments.
This talk will provide a brief description of the experimental methods and for PVES scattering, particularly for neutron skin measurements. It will also summarize the theoretical motivation for this type of measurement.
Measurement of the weak-mixing angle with CEvNS.
Coherent elastic neutrino-atom scattering.
Elucidating the electromagnetic properties of neutrinos with CEvNS.
We discuss new physics opportunities that are accessible from CEvNS measurements. Specifically, we explore the potential of probing neutrino transition magnetic moments and the existence of sterile neutrinos. We present the relevant constraints extracted from the existing COHERENT data as well as we estimate the projected sensitivities at future CEvNS experiments
The idea of measuring the coherent elastic nuclear scattering of neutrinos emitted by a high intensity $^{51}$Cr radioactive source is investigated.
To produce a high-intensity source, the radioactive material used in the GALLEX experiment (36 kg of Chromium 38.6 % enriched in $^{50}$Cr) could be reactivated to the intensity of a few MCi.
The advantages of this source are that the activity can be measured at a few per mill level and that the neutrino spectrum is well known. With a target volume of 2 dm$^3$ of low-threshold detectors, if the background is limited, the cross-section might be measured with few percent precision.
In this talk, the requirements for the experiment will be shown and the envisioned experimental challenges will also be discussed.
The work is based on arXiv:1905.10611.
The J-PARC Material and Life Science Experimental Facility (MLF) is a pulsed spallation neutron source in Tokai, Japan. 3 GeV protons produced by the Rapid Cycling Synchrotron (RCS) are directed onto a mercury target at 25 Hz to produce an intense source of neutrons and decay-at-rest neutrinos. In this talk, I will describe the MLF facility with a particular focus on the neutrino source characteristics. I will also describe an upcoming experiment called JSNS2 which will use the MLF neutrino flux to directly test the LSND anomaly and make various cross section measurements.
Reactor antineutrino fluxes and CEvNS
Summary of the discussions had over the course of the workshop and any plans developed for CE$\nu$NS-community efforts to participate in the Snowmass process.