First Results of the Phase II SIMPLE Dark Matter Search

TL;DR

This paper presents initial results from a Phase II dark matter search using superheated droplet detectors, setting new limits on WIMP interactions in both spin-dependent and spin-independent sectors.

Contribution

First experimental results from a 14.1 kgd phase of the SIMPLE superheated droplet detector dark matter search, improving constraints on WIMP-nucleus interactions.

Findings

Set a limit of |a_p| < 0.32 for WIMP mass 50 GeV/c2 in spin-dependent interactions.

Achieved a spin-independent WIMP-nucleon cross section limit of 2.3x10^-5 pb at 45 GeV/c2.

Reduced the allowed phase space for WIMP interactions compared to previous experiments.

Abstract

We report results of a 14.1 kgd measurement with 15 superheated droplet detectors of total active mass 0.208 kg, comprising the first stage of a 30 kgd Phase II experiment. In combination with the results of the neutron-spin sensitive XENON10 experiment, these results yield a limit of |a_p| < 0.32 for M_W = 50 GeV/c2 on the spin-dependent sector of weakly interacting massive particle-nucleus interactions with a 50% reduction in the previously allowed region of the phase space formerly defined by XENON, KIMS and PICASSO. In the spin-independent sector, a limit of 2.3x10-5 pb at M_W = 45 GeV/c2 is obtained.