These two plots show the current result of gain matching for L-arm prl1 and prl2 PMTs. For PMT no. 3 (starting from 0) in prl1, the peak position is low but the voltage is -1100V now. We didn't further increase the voltage to avoid burning the PMT. The pulse on the oscilloscope is pretty normal (amplitude is around 10-20 mV) with this voltage.