Instrumentation, acquisition and analysis of the Phase II SIMPLE dark matter search signals

TL;DR

This paper details the development and application of new instrumentation for the SIMPLE dark matter search, demonstrating background discrimination and analyzing initial results that align with simulations of ambient neutron interactions.

Contribution

It introduces new instrumentation for the SIMPLE experiment and shows evidence of discriminating between different background signals, advancing dark matter detection methods.

Findings

14 neutron-related events detected, consistent with simulations

Evidence of alpha- and neutron-induced event discrimination

Validation of background rejection techniques

Abstract

I describe the new instrumentation for the SIMPLE dark matter search experiment, and its use in identifying, validating and rejecting non-WIMP backgrounds in the first stage of the Phase II project measurements. Beyond intrinsic acoustic background discrimination, evidence is provided for discrimination between {\alpha}- and neutron-induced events via analysis of the signal parameters. Analysis of the first stage result of the Phase II measurements yields 14 events associated with the ambient neutron field, consistent with MCNP simulations which include all materials radio-assays and full measurement shielding.