Speaker
Description
The ICARUS detector, a key component of the Short Baseline Neutrino
(SBN) Program at Fermilab, is a 600-ton Liquid Argon Time Projection Chamber (LArTPC) equipped with a Light Detection System (LDS) that uses 360 Hamamatsu R5912-MOD 8-inch photomultiplier tubes (PMTs), specifically designed to operate under cryogenic conditions (∼87 K). These PMTs feed the trigger signal to the readout, improve the spatial and timing resolution of the events and contribute to cosmic rays mitigation.
During operation at Fermilab, a progressive degradation in PMT gain was
observed. We developed an experimental setup to investigate the temperature dependence of PMT performance. Gain measurements were carried out from room temperature to -70 ° C using an environmental chamber. The results show that, while the PMTs exhibit stable performance under ambient conditions, a significant and irreversible reduction in gain emerges at lower temperatures. Although -70◦C remains above liquid argon temperatures, the trend clearly reveals a gain-sensitive degradation mechanism.
A simplified physical model was developed to reproduce and interpret the
observed behavior. Based on these findings, a series of mitigation strategies were implemented in the ICARUS detector to preserve PMT performance and ensure reliable operation under cryogenic conditions.
