Detection efficiency measurement and operational tests of the X-Arapuca for the first module of DUNE far detector

Abstract

The Deep Underground Neutrino Experiment (DUNE) is a dual-site experiment for long-baseline neutrino oscillation studies, able to resolve the neutrino mass hierarchy and measure δ CP. DUNE will also have sensitivity to supernova neutrinos and to processes beyond the Standard Model, such as nucleon decay searches. The Far Detector (FD) will consist of four liquid argon TPC (17.5 kt total mass) with systems for the detection of charge and scintillation light produced by an ionization event. The charge detection system permits both calorimetry and position determination. In addition, the photon-detection system (PDS) enhances the detector capabilities for all DUNE physics drivers. The PDS of the first FD module consists of light collector modules placed in the inactive space between the innermost wire planes of the TPC anode. The light collectors, the so-called X-ARAPUCAS, are functionally a light trap that captures wavelength-shifted photons inside boxes with highly reflective internal surfaces where they are guided to Silicon Photo-multipliers (SiPM) by wavelength-shifting (WLS) bars. Functionality and operational tests of the X-ARAPUCAS to be installed in ProtoDUNE-SP phase II (FD DUNE prototype at the scale 1:20), as well as the measurement of their absolute detection efficiency is reported in this publication.

The DUNE Far Detector Vertical Drift Technology (Technical Design Report)

“…The performance and cost-effectiveness of three different cutout shapes and associated production costs are being evaluated as part of the final module evaluation, with a final decision as to their inclusion decided prior to the production readiness review (PRR). The required PDE for the PD modules is 2% with a target value of 3%, similar to the best achieved by the FD1-HD X-ARAPUCA [16,29,86,87]. Measurements of PDE have not yet been made on full-sized FD2-VD PD modules but the fundamental design of the X-ARAPUCA is the same as for FD1-HD, so we expect similar performance.…”

“…The reflectivity at 175 nm and 128 nm of the anode PCB, the field cage profiles, and the membrane cryostat wall materials are accounted for in the simulation. Finally, motivated by prototype measurements and simulations [16,29,86,87], the X-ARAPUCA detection efficiency is set to the target value of 3% at both 175 nm and 128 nm. In the light yield plots (Figure 6.4) the detection efficiency is a scale factor, as discussed below.…”

Cryogenic characterization of Hamamatsu HWB MPPCs for the DUNE photon detection system

“…From the 250 SiPMs provided of each model, 41 6-SiPMs boards were prepared, meaning that four SiPMs of each model were not used for the tests. From the 164 boards, 22 were used for SuperCell testing [7], thus not appearing in the following results.…”

Measurement of the photon detection efficiency of Hamamatsu VUV4 SiPMs at cryogenic temperature

“…The experimental setup was used for the PDE measurement of the DUNE-HD X-ARAPUCA1 [14,20]. It is composed by a 300 l cryogenic vessel with different concentric volumes disposed as shown in figure 4.…”