Low-threshold response of a scintillating xenon bubble chamber to nuclear and electronic recoils

TL;DR

This study demonstrates a xenon bubble chamber's ability to detect nuclear recoils as low as 1 keV with high sensitivity and negligible response to gamma rays, advancing low-threshold particle detection technology.

Contribution

The paper introduces a xenon bubble chamber capable of detecting ultra-low energy nuclear recoils down to 0.50 keV with minimal gamma-ray sensitivity, providing new calibration data and upper limits.

Findings

Sensitivity to ~1 keV nuclear recoils achieved.

Gamma-ray bubble nucleation probability limited to <1.1×10⁻⁶ at 0.50 keV.

Device operates effectively at thermodynamic thresholds as low as 0.50 keV.

Abstract

A device filled with pure xenon first demonstrated the ability to operate simultaneously as a bubble chamber and scintillation detector in 2017. Initial results from data taken at thermodynamic thresholds down to ~4 keV showed sensitivity to ~20 keV nuclear recoils with no observable bubble nucleation by $\gamma$-ray interactions. This paper presents results from further operation of the same device at thermodynamic thresholds as low as 0.50 keV, hardware limited. The bubble chamber has now been shown to have sensitivity to ~1 keV nuclear recoils while remaining insensitive to bubble nucleation by $\gamma$-rays. A robust calibration of the chamber's nuclear recoil nucleation response, as a function of nuclear recoil energy and thermodynamic state, is presented. Stringent upper limits are established for the probability of bubble nucleation by $\gamma$-ray-induced Auger cascades, with a limit of $<1.1\times10^{-6}$ set at 0.50 keV, the lowest thermodynamic threshold explored.