46 research outputs found
Applying Superfluid Helium to Light Dark Matter Searches: Demonstration of the HeRALD Detector Concept
The SPICE/HeRALD collaboration is performing R&D to enable studies of sub-GeV
dark matter models using a variety of target materials. Here we report our
recent progress on instrumenting a superfluid He target mass with a
transition-edge sensor based calorimeter to detect both atomic signals (e.g.
scintillation) and He quasiparticle (phonon and roton) excitations. The
sensitivity of HeRALD to the critical "quantum evaporation" signal from He
quasiparticles requires us to block the superfluid film flow to the
calorimeter. We have developed a heat-free film-blocking method employing an
unoxidized Cs film, which we implemented in a prototype "HeRALD v0.1" detector
of 10~g target mass. This article reports initial studies of the atomic
and quasiparticle signal channels. A key result of this work is the measurement
of the quantum evaporation channel's gain of , which will
enable He-based dark matter experiments in the near term. With this gain
the HeRALD detector reported here has an energy threshold of 145~eV at 5 sigma,
which would be sensitive to dark matter masses down to 220~MeV/c.Comment: 14 pages, 9 figure
Characterization of SABRE crystal NaI-33 with direct underground counting
Ultra-pure NaI(Tl) crystals are the key element for a model-independent
verification of the long standing DAMA result and a powerful means to search
for the annual modulation signature of dark matter interactions. The SABRE
collaboration has been developing cutting-edge techniques for the reduction of
intrinsic backgrounds over several years. In this paper we report the first
characterization of a 3.4 kg crystal, named NaI-33, performed in an underground
passive shielding setup at LNGS. NaI-33 has a record low K contamination
of 4.30.2 ppb as determined by mass spectrometry. We measured a light
yield of 11.10.2 photoelectrons/keV and an energy resolution of 13.2%
(FWHM/E) at 59.5 keV. We evaluated the activities of Ra and Th
inside the crystal to be Bq/kg and Bq/kg,
respectively, which would indicate a contamination from U and
Th at part-per-trillion level. We measured an activity of 0.510.02
mBq/kg due to Pb out of equilibrium and a quenching factor of
0.630.01 at 5304 keV. We illustrate the analyses techniques developed to
reject electronic noise in the lower part of the energy spectrum. A cut-based
strategy and a multivariate approach indicated a rate, attributed to the
intrinsic radioactivity of the crystal, of 1 count/day/kg/keV in the
[5-20] keV region
Background Determination for the LUX-ZEPLIN (LZ) Dark Matter Experiment
The LUX-ZEPLIN experiment recently reported limits on WIMP-nucleus
interactions from its initial science run, down to cm
for the spin-independent interaction of a 36 GeV/c WIMP at 90% confidence
level. In this paper, we present a comprehensive analysis of the backgrounds
important for this result and for other upcoming physics analyses, including
neutrinoless double-beta decay searches and effective field theory
interpretations of LUX-ZEPLIN data. We confirm that the in-situ determinations
of bulk and fixed radioactive backgrounds are consistent with expectations from
the ex-situ assays. The observed background rate after WIMP search criteria
were applied was events/keV/kg/day in the
low-energy region, approximately 60 times lower than the equivalent rate
reported by the LUX experiment.Comment: 25 pages, 15 figure
Projected sensitivities of the LUX-ZEPLIN experiment to new physics via low-energy electron recoils
LUX-ZEPLIN is a dark matter detector expected to obtain world-leading sensitivity to weakly-interacting massive particles interacting via nuclear recoils with a
âŒ
7
-tonne xenon target mass. This paper presents sensitivity projections to several low-energy signals of the complementary electron recoil signal type: 1) an effective neutrino magnetic moment, and 2) an effective neutrino millicharge, both for
p
p
-chain solar neutrinos, 3) an axion flux generated by the Sun, 4) axionlike particles forming the Galactic dark matter, 5) hidden photons, 6) mirror dark matter, and 7) leptophilic dark matter. World-leading sensitivities are expected in each case, a result of the large 5.6 t 1000 d exposure and low expected rate of electron-recoil backgrounds in the
<
100
â
â
keV
energy regime. A consistent signal generation, background model and profile-likelihood analysis framework is used throughout
A White Paper on keV sterile neutrino Dark Matter
We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involvedâcosmology, astrophysics, nuclear, and particle physicsâin each case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. We then round out the discussion by critically summarizing all known constraints on sterile neutrino Dark Matter arising from astrophysical observations, laboratory experiments, and theoretical considerations. In this context, we provide a balanced discourse on the possibly positive signal from X-ray observations. Another focus of the paper concerns the construction of particle physics models, aiming to explain how sterile neutrinos of keV-scale masses could arise in concrete settings beyond the Standard Model of elementary particle physics. The paper ends with an extensive review of current and future astrophysical and laboratory searches, highlighting new ideas and their experimental challenges, as well as future perspectives for the discovery of sterile neutrinos
First Dark Matter Search Results from the LUX-ZEPLIN (LZ) Experiment
The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a
dual-phase xenon time projection chamber operating at the Sanford Underground
Research Facility in Lead, South Dakota, USA. This Letter reports results from
LZ's first search for Weakly Interacting Massive Particles (WIMPs) with an
exposure of 60 live days using a fiducial mass of 5.5 t. A profile-likelihood
ratio analysis shows the data to be consistent with a background-only
hypothesis, setting new limits on spin-independent WIMP-nucleon, spin-dependent
WIMP-neutron, and spin-dependent WIMP-proton cross-sections for WIMP masses
above 9 GeV/c. The most stringent limit is set at 30 GeV/c, excluding
cross sections above 5.9 cm at the 90\% confidence level.Comment: 9 pages, 6 figures. See https://tinyurl.com/LZDataReleaseRun1 for a
data release related to this pape
A search for new physics in low-energy electron recoils from the first LZ exposure
The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a
dual-phase xenon time projection chamber. We report searches for new physics
appearing through few-keV-scale electron recoils, using the experiment's first
exposure of 60 live days and a fiducial mass of 5.5t. The data are found to be
consistent with a background-only hypothesis, and limits are set on models for
new physics including solar axion electron coupling, solar neutrino magnetic
moment and millicharge, and electron couplings to galactic axion-like particles
and hidden photons. Similar limits are set on weakly interacting massive
particle (WIMP) dark matter producing signals through ionized atomic states
from the Migdal effect.Comment: 13 pages, 10 figures. See https://tinyurl.com/LZDataReleaseRun1ER for
a data release related to this pape
A White Paper on keV Sterile Neutrino Dark Matter
We present a comprehensive review of keV-scale sterile neutrino Dark Matter,collecting views and insights from all disciplines involved - cosmology,astrophysics, nuclear, and particle physics - in each case viewed from boththeoretical and experimental/observational perspectives. After reviewing therole of active neutrinos in particle physics, astrophysics, and cosmology, wefocus on sterile neutrinos in the context of the Dark Matter puzzle. Here, wefirst review the physics motivation for sterile neutrino Dark Matter, based onchallenges and tensions in purely cold Dark Matter scenarios. We then round outthe discussion by critically summarizing all known constraints on sterileneutrino Dark Matter arising from astrophysical observations, laboratoryexperiments, and theoretical considerations. In this context, we provide abalanced discourse on the possibly positive signal from X-ray observations.Another focus of the paper concerns the construction of particle physicsmodels, aiming to explain how sterile neutrinos of keV-scale masses could arisein concrete settings beyond the Standard Model of elementary particle physics.The paper ends with an extensive review of current and future astrophysical andlaboratory searches, highlighting new ideas and their experimental challenges,as well as future perspectives for the discovery of sterile neutrinos