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Title: First Dark Matter Search Results from a 4-kg CF$_3$I Bubble Chamber Operated in a Deep Underground Site

First Dark Matter Search Results from a 4-kg CF$_3$I Bubble Chamber Operated in a Deep Underground Site New data are reported from the operation of a 4.0 kg CF{sub 3}I bubble chamber in the 6800 foot deep SNOLAB underground laboratory. The effectiveness of ultrasound analysis in discriminating alpha decay background events from single nuclear recoils has been confirmed, with a lower bound of >99.3% rejection of alpha decay events. Twenty single nuclear recoil event candidates and three multiple bubble events were observed during a total exposure of 553 kg-days distributed over three different bubble nucleation thresholds. The effective exposure for single bubble recoil-like events was 437.4 kg-days. A neutron background internal to the apparatus, of known origin, is estimated to account for five single nuclear recoil events and is consistent with the observed rate of multiple bubble events. This observation provides world best direct detection constraints on WIMP-proton spin-dependent scattering for WIMP masses >20 GeV/c{sup 2} and demonstrates significant sensitivity for spin-independent interactions.
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Publication Date:
OSTI Identifier:1039348
Report Number(s):FERMILAB-PUB-12-098-AD-AE-CD-E-PPD
arXiv eprint number arXiv:1204.3094; TRN: US1202147
DOE Contract Number:AC02-07CH11359
Resource Type:Journal Article
Research Org:Fermi National Accelerator Laboratory (FNAL), Batavia, IL
Sponsoring Org:DOE Office of Science
Country of Publication:United States
Language:English
Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS, 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS, 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ALPHA DECAY; BUBBLE CHAMBERS; BUBBLES; DETECTION; NEUTRONS; NONLUMINOUS MATTER; NUCLEATION; ORIGIN; SCATTERING; SENSITIVITY Astrophysics, Experiment-HEP, Experiment-Nucl