Development of a high-light-yield liquid argon detector using tetraphenyl butadiene and silicon photomultiplier array

TL;DR

This study optimized TPB coating and tested silicon photomultiplier arrays to enhance the light yield of liquid argon detectors, achieving high photon detection efficiency and reproducible TPB deposition techniques.

Contribution

It introduces a controlled TPB evaporation method and demonstrates the effective operation of TSV-MPPC sensors at liquid argon temperatures.

Findings

Achieved a light yield of 12.8 ± 0.3 p.e./keVee with optimized TPB deposition.

TSV-MPPC detected LAr scintillations with over 50% photon-detection efficiency.

Developed a reproducible TPB coating process for improved detector performance.

Abstract

To increase the light yield of a liquid Ar (LAr) detector, we optimized the evaporation technique of tetraphenyl butadiene (TPB) on the detector surface and tested the operability of a silicon photomultiplier (SiPM), namely, the multi-pixel photon counter with through-silicon-via (TSV-MPPC, Hamamatsu Photonics K.K.) at LAr temperature. TPB converts the LAr scintillations (vacuum ultraviolet light) to visible light, which can be detected by high-sensitivity photosensors. Because the light yield depends on the deposition mass of TPB on the inner surface of the detector, we constructed a well-controlled TPB evaporator to ensure reproducibility and measured the TPB deposition mass using a quartz crystal microbalance sensor. After optimizing the deposition mass of TPB (30 $\mu g/cm^2$ on the photosensor window and 40 $\mu g/cm^2$ on the detector wall), the light yield was 12.8 $\pm$ 0.3 p.e./keVee using PMTs with a quantum efficiency of approximately 30% for TPB-converted light. We also tested the low-temperature tolerance of TSV-MPPC, which has a high photon-detection efficiency, in the LAr environment. The TSV-MPPC detected the LAr scintillations converted by TPB with a photon-detection efficiency exceeding 50%.