First results of the Phase II SIMPLE dark matter search

Area of Science:

• Particle Physics
• Cosmology
• Astrophysics

Background:

• Weakly interacting massive particles (WIMPs) are leading candidates for dark matter.
• Direct detection experiments aim to observe WIMP interactions with atomic nuclei.
• Previous experiments like XENON10, KIMS, and PICASSO have constrained WIMP properties.

Purpose of the Study:

• To present results from the first stage of a 30 kg detector experiment.
• To establish new limits on WIMP-nucleus interactions.
• To combine results with previous experiments to improve sensitivity.

Main Methods:

• Utilized 15 superheated droplet detectors with a total active mass of 0.208 kg.
• Performed a 14.1 kg d measurement.
• Combined data with the neutron-spin sensitive XENON10 experiment.

Main Results:

• Achieved a limit of |a(p)|<0.32 for the spin-dependent sector at M(W)=50 GeV/c², reducing the allowed phase space by 50%.
• Obtained a limit of 2.3×10⁻⁵ pb for the spin-independent sector at M(W)=45 GeV/c².

Conclusions:

• The experiment significantly constrains WIMP properties in both spin-dependent and spin-independent interaction channels.
• These findings narrow down the parameter space for WIMP dark matter searches.
• The results pave the way for future, larger-scale WIMP detection experiments.