Analysis of Signal Waveform from a Midsize Liquid Argon Detector

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, which takes into account the liquid argon emission decay times together with the TPB re-emission process as well as the signal reflection effects, 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.