Analysis of signal waveform from a midsize liquid argon detetor

TL;DR

This paper presents an analysis of the waveform signals from a midsize liquid argon detector, modeling the light emission and reflection effects to determine detector characteristics like purity and validate signal features.

Contribution

It introduces a detailed waveform model incorporating TPB re-emission and reflection effects, validated by experimental data, to improve understanding of liquid argon detector signals.

Findings

The waveform model accurately describes the signal features.

The slow decay time constant correlates with liquid argon purity.

Reflection effects explain the post-peak hump structure.

Abstract

The midsize single-phase liquid argon prototype detector, operating at the surface laboratory, is designed to measure scintillation light emitted by the liquid argon (LAr). The detector employs 42 8-inch photomultiplier tubes (PMT) to collect the light. By analyzing the waveform of the signal, important detector characteristics such as the slow decay time constant that characterizes the purity of the liquid argon can be obtained. To describe the signal waveform, a model that considers the TPB re-emission process and the signal reflection effects based on the principles of liquid argon light emission, including fast and slow components of light decay, is used. The TPB re-emission process is introduced using a three-exponential time structure. Additionally, experimental results provide comprehensive validation for a post-peak hump structure, which is attributed to signal reflection.