The optimum voltage is within the first few points on the plateau. The plateau starts at about 0.903 volts on this graph. The optimum voltage that was found is about 0.998 volts.
The coincidence for counters six and seven was measure once for about ten minutes. The frequency was 654 counts/minute which is what the counts per minute for the coincidence of counters six, seven, and eight was divided by.
This performance study shows the desired distribution, Gaussian-shaped. The highest number of pulses occurs around 10 nanoseconds as it should. The study was run with the counter set to 0.998 volts.