Simulation results for a low energy nuclear recoil yields measurement in liquid xenon using the MiX detector

TL;DR

This paper investigates the feasibility of measuring ultra-low energy nuclear recoil yields in liquid xenon using the MiX detector and neutron capture, aiming to enhance dark matter detection sensitivity.

Contribution

It demonstrates through simulations that neutron capture events can be isolated and optimized in the MiX detector for ultra-low energy recoil measurements.

Findings

Neutron capture events can be distinguished from scattering events.

Optimal neutron moderator thickness improves capture rate.

Pulsed neutron generator parameters affect detection efficiency.

Abstract

Measuring the scintillation and ionization yields of liquid xenon in response to ultra-low energy nuclear recoil events is necessary to increase the sensitivity of liquid xenon experiments to light dark matter. Neutron capture on xenon can be used to produce nuclear recoil events with energies below $0.3$ keV$_\text{NR}$ via the asymmetric emission of $\gamma$ rays during nuclear de-excitation. The feasibility of an ultra-low energy nuclear recoil measurement using neutron capture was investigated for the Michigan Xenon (MiX) detector, a small dual-phase xenon time projection chamber that is optimized for a high scintillation gain. Simulations of the MiX detector, a partial neutron moderator, and a pulsed neutron generator indicate that a population of neutron capture events can be isolated from neutron scattering events. Further, the rate of neutron captures in the MiX detector was optimized by varying the thickness of the partial neutron moderator, neutron pulse width, and neutron pulse frequency.