A compact Optical Liquid Argon Facility at Roma Tre

TL;DR

This paper introduces a compact, high-purity liquid argon test facility at Roma Tre for measuring optical properties, utilizing direct immersion of VUV silicon photomultipliers to improve scintillation photon detection accuracy.

Contribution

It presents a novel compact setup with direct immersion photomultipliers for liquid argon scintillation studies, reducing systematic errors from wavelength shifters and light guides.

Findings

High-purity liquid argon achieved (≥99.9999%)

Direct immersion photomultipliers enable precise photon detection

Compact design facilitates optical property measurements

Abstract

In this paper we present a compact test facility for the measurement of optical properties of liquid argon as scintillator. The setup is under preparation at Roma Tre and it has a volume of 40 L liquid argon, which is liquefied from argon gas with a purity of $\ge 99.9999\%$ vol. To readout the scintillation photons from liquid argon with the highest intensity near 127 nm, we use the vacuum ultraviolet silicon photomultipliers from Hamamatsu. By submerging the photon detectors directly inside the liquid argon, we can eliminate the systematics from the wavelength shifter and light guides which have been commonly used to detect the scintillation photons of liquid argon.