Data from the operation of a bubble chamber filled with 3.5 kg of CF3I in a shallow underground site are reported. An analysis of ultrasound signals accompanying bubble nucleations confirms that alpha decays generate a significantly louder acoustic emission than single nuclear recoils, leading to an efficient background discrimination. Three dark matter candidate events were observed during an effective exposure of 28.1 kg-day, consistent with a neutron background. This observation provides the strongest direct detection constraint to date on WIMP-proton spin-dependent scattering for WIMP masses >20 GeV/c2.
@article{arxiv.1008.3518,
title = {Improved Limits on Spin-Dependent WIMP-Proton Interactions from a Two Liter CF$_3$I Bubble Chamber},
author = {E. Behnke and J. Behnke and S. J. Brice and D. Broemmelsiek and J. I. Collar and P. S. Cooper and M. Crisler and C. E. Dahl and D. Fustin and J. Hall and J. H. Hinnefeld and M. Hu and I. Levine and E. Ramberg and T. Shepherd and A. Sonnenschein and M. Szydagis},
journal= {arXiv preprint arXiv:1008.3518},
year = {2011}
}
Comments
4 pages, 4 figures V2 submitted to match journal version