The Cryogenic Dark Matter Search low ionization threshold experiment (CDMSlite) searches for interactions between dark matter particles and germanium nuclei in cryogenic detectors. The experiment has ...achieved a low energy threshold with improved sensitivity to low-mass ( < 10 GeV / c 2 ) dark matter particles. We present an analysis of the final CDMSlite dataset, taken with a different detector than was used for the two previous CDMSlite datasets. This analysis includes a data “salting” method to protect against bias, improved noise discrimination, background modeling, and the use of profile likelihood methods to search for a dark matter signal in the presence of backgrounds. We achieve an energy threshold of 70 eV and significantly improve the sensitivity for dark matter particles with masses between 2.5 and 10 GeV / c 2 compared to previous analyses. We set an upper limit on the dark matter-nucleon scattering cross section in germanium of 5.4 × 10 − 42 cm 2 at 5 GeV / c 2 , a factor of ~ 2.5 improvement over the previous CDMSlite result.
We report the first demonstration of a phonon-mediated silicon detector technology that provides a primary phonon measurement in a low-voltage region, and a simultaneous indirect measurement of the ...ionization signal through Neganov–Trofimov–Luke amplification in a high voltage region, both in a monolithic crystal. We present characterization of charge and phonon transport between the two stages of the detector and the resulting background discrimination capability at low energies. This new detector technology has the potential to significantly enhance the sensitivity of dark matter and coherent neutrino scattering experiments beyond the capabilities of current technologies that have limited discrimination at low energies.
This paper describes the operation of the Coherent CAPTAIN-Mills (CCM) detector located at the Los Alamos Neutron Science Center at Los Alamos National Laboratory. CCM is a 10-ton liquid argon ...detector located 20 meters from a high flux neutron/neutrino source and is designed to search for sterile neutrinos (νs’s) and light dark matter (LDM). An engineering run was performed in fall 2019 to study the characteristics of the CCM120 detector by searching for coherent scattering signals consistent with νs’s and LDM resulting from the production and decays of π+ and π0 in the tungsten target. New parameter space in a leptophobic dark matter (DM) model was excluded for DM masses between ~2.0 and 30 MeV. The lessons learned from this run have guided the development and construction of the new CCM200 detector that will begin operations in 2021 and significantly improve on these searches.
Large mass single electron resolution solid state detectors are desirable to search for low mass dark matter candidates and to measure coherent elastic neutrino nucleus scattering (CEνNS). Here, we ...present results from a novel 100 g phonon-mediated Si detector with a new interface architecture. This detector gives a baseline resolution of ∼1e−∕h+ pair and a leakage current on the order of 10−16 A. This was achieved by removing the direct electrical contact between the Si crystal and the metallic electrode, and by increasing the phonon absorption efficiency of the sensors. The phonon signal amplification in the detector shows a linear increase while the signal to noise ratio improves with bias voltage, up to 240 V. This feature enables the detector to operate at a low energy threshold which is beneficial for dark matter and CEνNS like searches.
Large mass single electron resolution solid state detectors are desirable to search for low mass dark matter candidates and to measure coherent elastic neutrino nucleus scattering (CEvNS). In this ...paper we present results from a novel 100 g phonon-mediated Si detector with a new interface architecture. This detector gives a baseline resolution of ~ 1e-/h+ pair and a leakage current on the order of 10-16 A. This was achieved by removing the direct electrical contact between the Si crystal and the metallic electrode, and by increasing the phonon absorption efficiency of the sensors. The phonon signal amplification in the detector shows a linear increase while the signal to noise ratio improves with bias voltage, up to 240 V. This feature enables the detector to operate at a low energy threshold which is beneficial for dark matter and CEvNS like searches.
We report the first results of a search for leptophobic dark matter (DM) from the Coherent–CAPTAIN-Mills (CCM) liquid argon (LAr) detector. An engineering run with 120 photomultiplier tubes (PMTs) ...and 17.9 × 1020 protons on target (POT) was performed in fall 2019 to study the characteristics of the CCM detector. The operation of this 10-ton detector was strictly light based with a threshold of 50 keV and used coherent elastic scattering off argon nuclei to detect DM. Despite only 1.5 months of accumulated luminosity, contaminated LAr, and nonoptimized shielding, CCM’s first engineering run has already achieved sensitivity to previously unexplored parameter space of light dark matter models with a baryonic vector portal. With an expected background of 115 005 events, we observe 115 005 + 16.5 events which is compatible with background expectations. For a benchmark mediator-to-DM mass ratio of mVB=mχ = 2.1, DM masses within the range 9 MeV ≲ mχ ≲ 50 MeV are excluded at 90% C. L. in the leptophobic model after applying the Feldman-Cousins test statistic. CCM’s upgraded run with 200 PMTs, filtered LAr, improved shielding, and 10 times more POT will be able to exclude the remaining thermal relic density parameter space of this model, as well as probe new parameter space of other leptophobic DM models.
Low-threshold sapphire detector for rare event searches Verma, S.; Maludze, S.; Lee, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2023, Letnik:
1046
Journal Article
Recenzirano
Odprti dostop
Low mass nuclear recoil dark matter and coherent-elastic-neutrino-nucleus-scattering (CEνNS) searches confront similar challenges in choosing ultra-low threshold and large-mass detectors. We report ...experimental results from a 100 g single-crystal sapphire detector design with a diameter of 76 mm and thickness of 4 mm instrumented with transition edge sensors (TES). Sapphire is a crystal of aluminum oxide (Al2O3) and has been found to be a good candidate for light mass dark matter search experiments due to its lower atomic mass compared to other detector materials such as germanium and silicon. This new phonon-assisted sapphire detector was characterized to yield a baseline recoil energy resolution of 28.4 ± 0.4 eV. The detector is designed to be sensitive to low-energy rare interactions with an intention to investigate the low-mass region of dark matter phase-space and search for CEνNS at the reactor site.
We present a new analysis of previously published SuperCDMS data using a profile likelihood framework to search for sub-GeV dark matter (DM) particles through two inelastic scattering channels: ...bremsstrahlung radiation and the Migdal effect. By considering these possible inelastic scattering channels, experimental sensitivity can be extended to DM masses that are undetectable through the DM-nucleon elastic scattering channel, given the energy threshold of current experiments. We exclude DM masses down to 220 MeV/c2 at 2.7 x 10-30 cm2 via the bremsstrahlung channel. The Migdal channel search provides overall considerably more stringent limits and excludes DM masses down to 30 MeV/ c2 at 5.0 x 10-30 cm2.
We report the fabrication and performance of an annular, cryogenic, phonon-mediated veto detector that can host an inner target detector, allowing substantial reduction in radiogenic backgrounds for ...rare event search experiments. A germanium veto detector of mass ∼500 g with an outer diameter of 76 mm and an inner diameter of 28 mm was produced inside of which was mounted a 25 mm diameter germanium inner target detector of mass ∼10 g. The detector was designed using inputs from a GEANT4 based simulation, where it was modeled to be sandwiched between two germanium detectors. The simulation showed that the background rates (dominated by gamma interactions) could be reduced by > 90%, and that such an arrangement is sufficient for aggressive background reduction needed for neutrino and dark matter search experiments. Operating at mK temperatures at the experimental site, the veto detector prototype achieved a baseline resolution of 1.24 ± 0.02 keV while hosting a functional inner target detector. The baseline resolution of the inner target detector was 147 ± 2 eV. The experimental results of an identical detector arrangement are in excellent agreement with the simulation.
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