The optical simulation model of the DarkSide-20k Veto detector

TL;DR

This paper develops a detailed optical simulation model for the DarkSide-20k veto detector, crucial for maximizing light collection efficiency in dark matter detection experiments.

Contribution

It presents a comprehensive Geant4-based optical simulation model tailored for the DarkSide-20k veto detector, incorporating optical properties and reflectivity effects.

Findings

Optical properties significantly influence light yield.

Simulation helps optimize detector design.

Reflectivity of walls impacts detection efficiency.

Abstract

DarkSide-20k is a rare-event search experiment aimed at finding signals of dark matter particles. It is a dual-phase detector that registers ionisation and scintillation signals originating from the particles interacting with the liquid argon detector medium. It is enclosed in a single-phase liquid argon neutron veto tank, equipped with Gd-loaded panels for capturing neutrons. Since vetoing and particle identification are carried out using the light signal, it is crucial to maximise the light yield. Light collection efficiency depends on optical properties of the detector and particularly for the veto detector, which has a photosensor coverage of the order of a per cent, the reflectivity of the walls has a big impact. To quantify the amount of collected light, a comprehensive Geant4 simulation is performed, which uses optical characterisation data. In this work, a detailed description of the optics model for the veto of the experiment will be discussed.