Improved Spin Dependent Limits from the PICASSO Dark Matter Search Experiment

Authors:
  • TCThe PICASSO Collaboration
    The PICASSO Collaboration
  • MBM. Barnabe-Heider
    M. Barnabe-Heider
  • EBE. Behnke
    E. Behnke
  • KCK. Clark
    K. Clark
  • MMM. Di Marco
    M. Di Marco
  • PDP. Doane
    P. Doane
  • MGM. -H. Genest
    M. -H. Genest
  • RGR. Gornea
    R. Gornea
  • RGR. Guenette
    R. Guenette
  • SKS. Kanagalingam
    S. Kanagalingam
  • CKC. B. Krauss
    C. B. Krauss
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Abstract
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.