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A compact Optical Liquid Argon Facility at Roma Tre

Hexi Shi, Valerio D'Andrea, Krzysztof Szczepaniec, Giuseppe Salamanna, Diego Tagnani

Abstract

In this paper we present a compact test facility for the measurement of optical properties of liquid argon as scintillation detector. 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 wave length shifter and light guides which have been commonly used to detect the scintillation photons of liquid argon.

A compact Optical Liquid Argon Facility at Roma Tre

Abstract

In this paper we present a compact test facility for the measurement of optical properties of liquid argon as scintillation detector. 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 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 wave length shifter and light guides which have been commonly used to detect the scintillation photons of liquid argon.
Paper Structure (9 sections, 4 figures)

This paper contains 9 sections, 4 figures.

Table of Contents

  1. Introduction
  2. Experimental setup
  3. Cryogenics for LAr
  4. Liquefaction of argon
  5. Photon detector layout and readout
  6. Photon source and calibration
  7. Readout electronics
  8. Data acquisition
  9. Current status and plans

Figures (4)

  • Figure 1: The P&ID diagram of the OLAF setup. Details in text.
  • Figure 2: The OLAF setup up at the laboratory of Roma Tre: (a) the main vessel with the LAr surrounded by LN$_2$ and vacuum jacketed vessels; (b) photo showing other auxiliary components for OLAF operation.
  • Figure 3: Middle: the prototype mechanical tower structure which hosts the SiPMs and the photon sources; left: metallic holder to host a single SiPM and to fix it to the tower; top right: a 3D rendering that shows the radioactive source housing and the three SiPMs defining the trigger; bottom right: prototype to test the mounting of LED source to the source holder.
  • Figure 4: A typical waveform of the LAr scintillation photon detected by the VUV SiPM. The digitizer operated at the sampling rate of 8 ns per sample; the vertical axis is in ADC unit.