The PICASSO experiment reports an improved limit for the existence of cold dark matter WIMPs interacting via spin-dependent interactions with nuclei. The experiment is installed in the Sudbury Neutrino Observatory at a depth of 2070 m. With superheated C4F10 droplets as the active material, and an exposure of 1.98+-0.19 kgd, no evidence for a WIMP signal was found. For a WIMP mass of 29 GeV/c2, limits on the spin-dependent cross section on protons of sigma_p = 1.31 pb and on neutrons of sigma_n = 21.5 pb have been obtained at 90% C.L. In both cases, some new parameter space in the region of WIMP masses below 20 GeV/c2 has now been ruled out. The results of these measurements are also presented in terms of limits on the effective WIMP-proton and neutron coupling strengths a_p and a_n.
@article{arxiv.hep-ex/0502028,
title = {Improved Spin Dependent Limits from the PICASSO Dark Matter Search Experiment},
author = {The PICASSO Collaboration and M. Barnabe-Heider and E. Behnke and K. Clark and M. Di Marco and P. Doane and W. Feighery and M. -H. Genest and R. Gornea and R. Guenette and S. Kanagalingam and C. B. Krauss and C. Leroy and L. Lessard and I. Levine and J. -P. Martin and C. Muthusi and A. J. Noble and R. Noulty and U. Wichoski and V. Zacek},
journal= {arXiv preprint arXiv:hep-ex/0502028},
year = {2008}
}
Comments
24 pages, 6 figures; text expanded for clarity, new figure added. To be published in Phys. Lett. B