Since the power connection was bad in the PMT in counter three the counter was taken apart and a new PMT attached to the scintillator on July 10th. This is the plateau plot of the new counter.
The plateau is about 0.980 to 1.181 volts. The optimum voltage seems to be about should be within this value and was determined using performance studies.
This study was run at 1.000 volts. This appears to be the optimum voltage because a lower voltage gives less pulses and a higher one too many short pulses. The graph should be approximately guassian with the highest point at about ten nanoseconds.