Electron - nuclear recoil discrimination by pulse shape analysis

TL;DR

This paper demonstrates that pulse shape analysis in superfluid 3He bolometers can distinguish between muon, neutron, and heater events, potentially improving dark matter detection capabilities.

Contribution

It reveals that thermalization time constants depend on particle type, enabling particle discrimination in superfluid 3He detectors, contrary to previous assumptions.

Findings

Thermalization time constants vary with particle type.

Muon and neutron events show distinguishable pulse shapes.

Heater pulse events mimic particle interactions.

Abstract

In the framework of the ``ULTIMA'' project, we use ultra cold superfluid 3He bolometers for the direct detection of single particle events, aimed for a future use as a dark matter detector. One parameter of the pulse shape observed after such an event is the thermalization time constant. Until now it was believed that this parameter only depends on geometrical factors and superfluid 3He properties, and that it is independent of the nature of the incident particles. In this report we show new results which demonstrate that a difference for muon- and neutron events, as well as events simulated by heater pulses exist. The possibility to use this difference for event discrimination in a future dark matter detector will be discussed.