Prototyping an Active Neutron Veto for SuperCDMS

TL;DR

This paper explores the design and testing of an active neutron veto system using organic liquid scintillator and wavelength-shifting fibers to reduce neutron background in the SuperCDMS dark matter detector.

Contribution

It presents a novel active neutron veto design tailored for the SuperCDMS experiment, including R&D results and prototype performance evaluations.

Findings

Veto design achieves promising neutron detection efficiency.

Prototype testing demonstrates feasibility within space constraints.

Enhanced neutron capture agents improve veto performance.

Abstract

Neutrons, originating cosmogenically or from radioactive decays, can produce signals in dark matter detectors that are indistinguishable from Weakly Interacting Massive Particles (WIMPs). To combat this background for the SuperCDMS SNOLAB experiment, we are investigating designs for an active neutron veto within the constrained space of the compact SuperCDMS passive shielding. The current design employs an organic liquid scintillator mixed with an agent to enhance thermal neutron captures, with the scintillation light collected using wavelength-shifting fibers and read out by silicon photo-multipliers. We will describe the proposed veto and its predicted efficiency in detail and give some recent results from our R&D and prototyping efforts.