New limits on the WIMP Cold Dark Matter interaction cross section from the UK experiment

The UK Dark Matter Collaboration has run a 5-6 kg NaI detector in a low-noise underground site for about a year. Signatures of Cold Dark Matter (CDM) interactions are sought using pulse shape discrimination techniques by searching for the relatively short scintillation pulses arising from nuclear recoils among the longer background events from residual radioactivity in the detector. Here we report on an improvement to the limits on the CDM cross section for spin dependent interactions using our latest data from a crystal with improved detection efficiency and taking into account new calculations of the spin factor correction between the nucleus and nucleon-supersymmetric particle cross sections.