The DireXeno Experiment -- Measuring Correlated Scintillation Signatures in Liquid Xenon

TL;DR

This paper introduces the DireXeno detector designed to measure the detailed spatial and temporal properties of liquid xenon scintillation light, aiming to identify correlated emission patterns that could improve background rejection and directional detection in rare event searches.

Contribution

The paper presents a novel detector setup and statistical methods to detect scintillation anisotropy and correlations in liquid xenon, advancing understanding of microphysics relevant to dark matter and neutrino experiments.

Findings

Achieved time resolution of ≤1.3 ns FWHM for individual photons.

Demonstrated detector stability over 44 days of operation.

Showed potential to detect scintillation anisotropy as small as 10%.

Abstract

We present a detector apparatus, DireXeno (DIRectinal Xenon), designed to measure the spatial and temporal properties of scintillation in liquid xenon to very high accuracy. The properties of scintillation are of primary importance for dark matter and neutrinoless double beta decay experiments, however the complicated microphysics involved limits theoretical predictions. We will explore the possibility that scintillation emission exhibits correlation in light emission such as super-radiance, which depends on the type of interaction. Such properties of scintillation light may open a new window for background rejection as well as directionality measurements. We present the technical design and the concepts driving it, and demonstrate that statistical treatment will enable detecting anisotropy of as little as 10% of the photons. We show results from commissioning runs in which the detector operated for over 44 days in stable conditions. The time resolution for individual photons in different PMTs was measured to be $\lesssim1.3$ ns FWHM, corresponding to $\lesssim0.55$ ns (1 $\sigma$).