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This content will become publicly available on January 1, 2019

Title: Low-mass dark matter search with CDMSlite

The SuperCDMS experiment is designed to directly detect WIMPs (Weakly Interacting Massive Particles) that may constitute the dark matter in our galaxy. During its operation at the Soudan Underground Laboratory, germanium detectors were run in the CDMSlite (Cryogenic Dark Matter Search low ionization threshold experiment) mode to gather data sets with sensitivity specifically for WIMPs with masses $${<}10$$ GeV/$c^2$. In this mode, a large detector-bias voltage is applied to amplify the phonon signals produced by drifting charges. This paper presents studies of the experimental noise and its effect on the achievable energy threshold, which is demonstrated to be as low as 56 eV$$_{\text{ee}}$$ (electron equivalent energy). The detector biasing configuration is described in detail, with analysis corrections for voltage variations to the level of a few percent. Detailed studies of the electric-field geometry, and the resulting successful development of a fiducial parameter, eliminate poorly measured events, yielding an energy resolution ranging from $${\sim}$$9 eV$$_{\text{ee}}$$ at 0 keV to 101 eV$$_{\text{ee}}$$ at $${\sim}$$10 keV$$_{\text{ee}}$$. New results are derived for astrophysical uncertainties relevant to the WIMP-search limits, specifically examining how they are affected by variations in the most probable WIMP velocity and the galactic escape velocity. These variations become more important for WIMP masses below 10 GeV/$c^2$. Finally, new limits on spin-dependent low-mass WIMP-nucleon interactions are derived, with new parameter space excluded for WIMP masses $${\lesssim}$$3 GeV/$c^2$.
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Publication Date:
Report Number(s):
FERMILAB-PUB-17-265-AE; arXiv:1707.01632
Journal ID: ISSN 2470-0010; PRVDAQ; 1608856
Grant/Contract Number:
AC02-07CH11359; AC05-76RL01830; AC02-76SF00515; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 97; Journal Issue: 2; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
SuperCDMS Collaboration
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
1413685
Alternate Identifier(s):
OSTI ID: 1417221; OSTI ID: 1435109