A study about effects of background light on the gain of Photomultiplier Tubes

Abstract

Photomultiplier Tubes (PMT) are mostly used in air Cherenkov light detection in extensive air shower of cosmic rays. The Cherenkov telescopes work at clear and moonless nights, therefore it is susceptible to the background of stars in the sky; and with the Earth’s rotation and revolution, the affection of background is different yet. In this case, we conducted an experiment to evaluate the impact of night-sky background (NSB) to the gain of PMTs. By optimizing the voltage divider of PMT, one can decrease the influence brought by NSB on the gain of PMT.