Enhancement of the X-Arapuca photon detection device for the DUNE experiment

TL;DR

This paper reports on the enhancement and characterization of the X-Arapuca photon detection device for DUNE, achieving a 50% efficiency increase through new materials and detailed measurements, supporting large-scale neutrino detection and other liquid argon experiments.

Contribution

The study introduces a new photon downshifting material and provides detailed efficiency measurements of the X-Arapuca device, improving its performance for large-scale liquid argon detectors.

Findings

Photon detection efficiency increased by about 50%.

Detailed efficiency measurements along the device axis were performed.

Enhanced device design supports future large-scale liquid argon experiments.

Abstract

In the Deep Underground Neutrino Experiment (DUNE), the VUV LAr luminescence is collected by light trap devices named X-Arapuca, sizing (480x93) mm2. Six thousand of these units will be deployed in the first DUNE ten kiloton far detector module. In this work we present the first characterization of the photon detection efficiency of an X-Arapuca device sizing (200x75) mm2 via a complete and accurate set of measurements along the cell longitudinal axis with a movable 241-Am source. The MPPCs photosensors are readout by a cryogenic transimpedance amplifier to enhance the single photoelectron sensitivity and improve the signal-to-noise while ganging 8 MPPC for a total surface of 288 mm2. Moreover we developed a new photon downshifting polymeric material, by which the X-Arapuca photon detection efficiency was enhanced of about +50% with respect to the baseline off-shell product deployed in the standard device configuration. The achieved results are compared to previous measurements on a half size X-Arapuca device, with a fixed source facing the center, with no cold amplification stage, and discussed in view of the DUNE full size optical cell construction for both the horizontal and the vertical drift configurations of the DUNE TPC design and in view of liquid Argon doping by ppms of Xe. Other particle physics projects adopting Liquid Argon as target or active veto, as Dark Side and LEGEND or the DUNE Near Detector will take advantage of this novel wavelength shifting material.