arXiv subjects

A. J. Anderson

Publications and source records attributed to A. J. Anderson.

99 records · Page 6Linked to original sources

arXiv2013

Demonstration of Surface Electron Rejection with Interleaved Germanium Detectors for Dark Matter Searches

The SuperCDMS experiment in the Soudan Underground Laboratory searches for dark matter with a 9-kg array of cryogenic germanium detectors. Symmetric sensors on opposite sides measure both charge and phonons from each particle interaction, providing excellent discrimination between electron and nuclear recoils, and between surface and interior events. Surface event rejection capabilities were tested with two $^{210}$Pb sources producing $\sim$130 beta decays/hr. In $\sim$800 live hours, no events leaked into the 8--115 keV signal region, giving upper limit leakage fraction $1.7 \times 10^{-5}$ at 90% C.L., corresponding to $< 0.6$ surface event background in the future 200-kg SuperCDMS SNOLAB experiment.

physics.ins-det↗

arXiv2013

Silicon detector results from the first five-tower run of CDMS II

We report results of a search for Weakly Interacting Massive Particles (WIMPs) with the Si detectors of the CDMS II experiment. This report describes a blind analysis of the first data taken with CDMS II's full complement of detectors in 2006-2007; results from this exposure using the Ge detectors have already been presented. We observed no candidate WIMP-scattering events in an exposure of 55.9 kg-days before analysis cuts, with an expected background of ~1.1 events. The exposure of this analysis is equivalent to 10.3 kg-days over a recoil energy range of 7-100 keV for an ideal Si detector and a WIMP mass of 10 GeV/c2. These data set an upper limit of 1.7x10-41 cm2 on the WIMP-nucleon spin-independent cross section of a 10 GeV/c2 WIMP. These data exclude parameter space for spin-independent WIMP-nucleon elastic scattering that is relevant to recent searches for low-mass WIMPs.

astro-ph.CO↗

arXiv2012

Search for annual modulation in low-energy CDMS-II data

We report limits on annual modulation of the low-energy event rate from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Such a modulation could be produced by interactions from Weakly Interacting Massive Particles (WIMPs) with masses ~10 GeV/c^2. We find no evidence for annual modulation in the event rate of veto-anticoincident single-detector interactions consistent with nuclear recoils, and constrain the magnitude of any modulation to <0.06 event [keVnr kg day]^-1 in the 5-11.9 keVnr energy range at the 99% confidence level. These results disfavor an explanation for the reported modulation in the 1.2-3.2 keVee energy range in CoGeNT in terms of nuclear recoils resulting from elastic scattering of WIMPs at >98% confidence. For events consistent with electron recoils, no significant modulation is observed for either single- or multiple-detector interactions in the 3.0-7.4 keVee range.

astro-ph.CO↗

arXiv2012

Measuring Active-to-Sterile Neutrino Oscillations with Neutral Current Coherent Neutrino-Nucleus Scattering

Light sterile neutrinos have been introduced as an explanation for a number of oscillation signals at $Δm^2 \sim 1$ eV$^2$. Neutrino oscillations at relatively short baselines provide a probe of these possible new states. This paper describes an accelerator-based experiment using neutral current coherent neutrino-nucleus scattering to strictly search for active-to-sterile neutrino oscillations. This experiment could, thus, definitively establish the existence of sterile neutrinos and provide constraints on their mixing parameters. A cyclotron-based proton beam can be directed to multiple targets, producing a low energy pion and muon decay-at-rest neutrino source with variable distance to a single detector. Two types of detectors are considered: a germanium-based detector inspired by the CDMS design and a liquid argon detector inspired by the proposed CLEAR experiment.

hep-ph↗

arXiv2011

Modeling phase-separated transition-edge sensors in SuperCDMS detectors

The SuperCDMS experiment implements transition-edge sensors to measure athermal phonons produced by nuclear recoils in Ge crystals. We discuss a numerical simulation of these TES devices and a procedure for tuning the free model parameters to data, which reproduces superconducting-to-normal phase separation within a TES. This tuning provides insight into the behavior of the TESs, allows us to study the phase-separation length to optimize our detector design, and is integrated into a more complete simulation of the phonon and charge physics of SuperCDMS detectors.

physics.ins-det↗

arXiv2011

Simulations of Noise in Phase-Separated Transition-Edge Sensors for SuperCDMS

We briefly review a simple model of superconducting-normal phase-separation in transition-edge sensors in the SuperCDMS experiment. After discussing some design considerations relevant to the TES in the detectors, we study noise sources in both the phase-separated and phase-uniform cases. Such simulations are valuable for optimizing the critical temperature and TES length of future SuperCDMS detectors.

physics.ins-det↗

arXiv2011

Coherent Neutrino Scattering in Dark Matter Detectors

Coherent elastic neutrino- and WIMP-nucleus interaction signatures are expected to be quite similar. This paper discusses how a next generation ton-scale dark matter detector could discover neutrino-nucleus coherent scattering, a precisely-predicted Standard Model process. A high intensity pion- and muon- decay-at-rest neutrino source recently proposed for oscillation physics at underground laboratories would provide the neutrinos for these measurements. In this paper, we calculate raw rates for various target materials commonly used in dark matter detectors and show that discovery of this interaction is possible with a 2 ton$\cdot$year GEODM exposure in an optimistic energy threshold and efficiency scenario. We also study the effects of the neutrino source on WIMP sensitivity and discuss the modulated neutrino signal as a sensitivity/consistency check between different dark matter experiments at DUSEL. Furthermore, we consider the possibility of coherent neutrino physics with a GEODM module placed within tens of meters of the neutrino source.

hep-ph↗

arXiv2011

Validation of Phonon Physics in the CDMS Detector Monte Carlo

The SuperCDMS collaboration is a dark matter search effort aimed at detecting the scattering of WIMP dark matter from nuclei in cryogenic germanium targets. The CDMS Detector Monte Carlo (CDMS-DMC) is a simulation tool aimed at achieving a deeper understanding of the performance of the SuperCDMS detectors and aiding the dark matter search analysis. We present results from validation of the phonon physics described in the CDMS-DMC and outline work towards utilizing it in future WIMP search analyses.

astro-ph.IM↗

arXiv2011

Sterile Neutrinos, Coherent Scattering and Oscillometry Measurements with Low-temperature Bolometers

Coherent neutrino-nucleon scattering offers a unique approach in the search for physics beyond the Standard Model. When used in conjunction with mono-energetic neutrino sources, the technique can be sensitive to the existence of light sterile neutrinos. The ability to utilize such reactions has been limited in the past due to the extremely low energy threshold (10-50 eV) needed for detection. In this paper, we discuss an optimization of cryogenic solid state bolometers that enables reaching extremely low kinetic energy thresholds. We investigate the sensitivity of an array of such detectors to neutrino oscillations to sterile states. A recent analysis of available reactor data appears to favor the existence of such such a sterile neutrino with a mass splitting of $|Δm_{\rm sterile}|^2 \ge 1.5$ eV$^2$ and mixing strength of $\sin^2{2θ_{\rm sterile}} = 0.17\pm 0.08$ at 95% C.L. An array of such low-threshold detectors would be able to make a definitive statement as to the validity of the interpretation.

hep-ph↗