Abstract
Abstract
With the expanding reach of physics, xenon-based detectors
such as PandaX-4T in the China Jinping Underground Laboratory aim to
cover an energy range from sub-keV to multi-MeV. A linear
response of the photomultiplier tubes (PMTs) is required for both
scintillation and electroluminescence signals. Through a dedicated
bench test, we investigated the cause of the non-linear response in
the Hamamatsu R11410-23 PMTs used in PandaX-4T. The saturation and
suppression of the PMT waveform observed during the commissioning of
PandaX-4T were caused by the high-voltage divider base. The bench
test data validated the de-saturation algorithm used in the
PandaX-4T data analysis. We also confirmed the improvement in
linearity of a new PMT base design with three more low radioactivity
capacitors at later dynodes, which will be used to upgrade the PMT
readout system in PandaX-4T.