12 research outputs found
Search for low-mass dark matter via bremsstrahlung radiation and the Migdal effect in SuperCDMS
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 2.7×10-30 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 5.0×10-30 cm2
G4CMP: Condensed Matter Physics Simulation Using the Geant4 Toolkit
G4CMP simulates phonon and charge transport in cryogenic semiconductor
crystals using the Geant4 toolkit. The transport code is capable of simulating
the propagation of acoustic phonons as well as electron and hole charge
carriers. Processes for anisotropic phonon propagation, oblique charge-carrier
propagation, and phonon emission by accelerated charge carriers are included.
The simulation reproduces theoretical predictions and experimental observations
such as phonon caustics, heat-pulse propagation times, and mean charge-carrier
drift velocities. In addition to presenting the physics and features supported
by G4CMP, this report outlines example applications from the dark matter and
quantum information science communities. These communities are applying G4CMP
to model and design devices for which the energy transported by phonons and
charge carriers is germane to the performance of superconducting instruments
and circuits placed on silicon and germanium substrates. The G4CMP package is
available to download from GitHub: github.com/kelseymh/G4CMP.Comment: 21 pages, 11 figures, 10 table
Ionization yield measurement in a germanium CDMSlite detector using photo-neutron sources
Two photo-neutron sources, YBe and SbBe, have been
used to investigate the ionization yield of nuclear recoils in the CDMSlite
germanium detectors by the SuperCDMS collaboration. This work evaluates the
yield for nuclear recoil energies between 1 keV and 7 keV at a temperature of
50 mK. We use a Geant4 simulation to model the neutron spectrum assuming
a charge yield model that is a generalization of the standard Lindhard model
and consists of two energy dependent parameters. We perform a likelihood
analysis using the simulated neutron spectrum, modeled background, and
experimental data to obtain the best fit values of the yield model. The
ionization yield between recoil energies of 1 keV and 7 keV is shown to be
significantly lower than predicted by the standard Lindhard model for
germanium. There is a general lack of agreement among different experiments
using a variety of techniques studying the low-energy range of the nuclear
recoil yield, which is most critical for interpretation of direct dark matter
searches. This suggests complexity in the physical process that many direct
detection experiments use to model their primary signal detection mechanism and
highlights the need for further studies to clarify underlying systematic
effects that have not been well understood up to this point
Light Dark Matter Search with a High-Resolution Athermal Phonon Detector Operated Above Ground
We present limits on spin-independent dark matter-nucleon interactions using
a Si athermal phonon detector with a baseline energy
resolution of
. This exclusion analysis sets the most
stringent dark matter-nucleon scattering cross-section limits achieved by a
cryogenic detector for dark matter particle masses from to
, with a raw exposure of
acquired at an above-ground facility. This work illustrates the scientific
potential of detectors with athermal phonon sensors with eV-scale energy
resolution for future dark matter searches.Comment: 7 pages, 4 figures, this version includes ancillary files from
official data releas
Search for low-mass dark matter via bremsstrahlung radiation and the Migdal effect in SuperCDMS
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 2.7×10−30  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 5.0×10−30  cm2
A Search for Low-mass Dark Matter via Bremsstrahlung Radiation and the Migdal Effect in SuperCDMS
We present a new analysis of previously published of 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 at
via the bremsstrahlung channel. The Migdal
channel search provides overall considerably more stringent limits and excludes
DM masses down to at .Comment: Submitted to PR
First measurement of the nuclear-recoil ionization yield in silicon at 100 eV
We measured the nuclear--recoil ionization yield in silicon with a cryogenic
phonon-sensitive gram-scale detector. Neutrons from a mono-energetic beam
scatter off of the silicon nuclei at angles corresponding to energy depositions
from 4\,keV down to 100\,eV, the lowest energy probed so far. The results show
no sign of an ionization production threshold above 100\,eV. These results call
for further investigation of the ionization yield theory and a comprehensive
determination of the detector response function at energies below the keV
scale
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Constraints on Lightly Ionizing Particles from CDMSlite.
The Cryogenic Dark Matter Search low ionization threshold experiment (CDMSlite) achieved efficient detection of very small recoil energies in its germanium target, resulting in sensitivity to lightly ionizing particles (LIPs) in a previously unexplored region of charge, mass, and velocity parameter space. We report first direct-detection limits calculated using the optimum interval method on the vertical intensity of cosmogenically produced LIPs with an electric charge smaller than e/(3×10^{5}), as well as the strongest limits for charge ≤e/160, with a minimum vertical intensity of 1.36×10^{-7}  cm^{-2} s^{-1} sr^{-1} at charge e/160. These results apply over a wide range of LIP masses (5  MeV/c^{2} to 100  TeV/c^{2}) and cover a wide range of βγ values (0.1-10^{6}), thus excluding nonrelativistic LIPs with βγ as small as 0.1 for the first time