PMT Gain Measurement

A Lecroy Wavesurfer Oscilloscope was used to self-trigger on signal pulses from a PMT. Various biases were applied. I began at the highest bias, 2200V, and lowered the trigger threshold until lowering it had no further effect on the mean of pulse amplitude histogram generated. For 2200V, a scale of 10mV/division and a threshold of 5 mV was used. 5000 data points were collected for each bias. Pulse area was used in analysis.

From pulse area, gain was calculated using (1): (source: http://www.hep.umn.edu/cdms/cdms_restricted/chagani/thesis.pdf)

In this case, the load resistance is 50Ω.

Figure 1:	Figure 2:

An extra peak is seen at 0.0015 nVs. As this was the lowest voltage measured, noise pulses were observed when self-triggering. These noise pulses fluctuate wildly but tended to have a net positive area. Below this bias voltage, these noise pulses overwhelmed dark count pulses.
Figure 3:	Figure 4:

Figure 5:	Figure 6:

Figure 7:	Figure 8:

Figure 9:	Figure 10:

Figure 11:	Figure 12:

Figure 13:

Figure 14: Gain Plot

The value of the slope has units of V^-1. The intercept is unitless. Vertical error bars are too small to be seen, but were determined using the GetParError() function in Root.

waveform_reduction_sipmGain.cxx
sipmGain_plot.C

−Table of Contents

Procedure

Data

Analysis

Analysis Programs