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

Journal Article · Sun Apr 01 00:00:00 EDT 2012

OSTI ID:1039348

Behnke, E; Behnke, J; Brice, S J; Broemmelsiek, D; Collar, J I; Conner, A; Cooper, P S; Crisler, M; Dahl, C E; Fustin, D; Grace, E

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.

• Research Organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 1039348
• Report Number(s): FERMILAB-PUB-12-098-AD-AE-CD-E-PPD; arXiv eprint number arXiv:1204.3094; TRN: US1202147
• Country of Publication: United States
• Language: English

Related Subjects

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