Low-energy (0.7-74 keV) nuclear recoil calibration of the LUX dark matter experiment using D-D neutron scattering kinematics

TL;DR

This paper presents a calibration of nuclear recoil signals in liquid xenon for the LUX dark matter detector using mono-energetic neutrons, enabling better understanding of low-energy interactions crucial for dark matter searches.

Contribution

It introduces an in situ calibration method for nuclear recoils down to 0.7 keV in liquid xenon, improving the accuracy of signal models for dark matter detection.

Findings

Measured charge and light yields at low recoil energies.

Demonstrated ionization and scintillation signals down to ~1 keV.

Enhanced calibration data for liquid xenon detectors.

Abstract

The Large Underground Xenon (LUX) experiment is a dual-phase liquid xenon time projection chamber (TPC) operating at the Sanford Underground Research Facility in Lead, South Dakota. A calibration of nuclear recoils in liquid xenon was performed $\textit{in situ}$ in the LUX detector using a collimated beam of mono-energetic 2.45 MeV neutrons produced by a deuterium-deuterium (D-D) fusion source. The nuclear recoil energy from the first neutron scatter in the TPC was reconstructed using the measured scattering angle defined by double-scatter neutron events within the active xenon volume. We measured the absolute charge ($Q_{y}$) and light ($L_{y}$) yields at an average electric field of 180 V/cm for nuclear recoil energies spanning 0.7 to 74 keV and 1.1 to 74 keV, respectively. This calibration of the nuclear recoil signal yields will permit the further refinement of liquid xenon nuclear recoil signal models and, importantly for dark matter searches, clearly demonstrates measured ionization and scintillation signals in this medium at recoil energies down to $\mathcal{O}$(1 keV).