PMT spectra of Am-241

PMT 14 was run with a bias voltage of -1100 V with scintillator 1-66-? and Am-241 with a copper collimator attached to plastic in the darkroom. The connection to the DAQ board was modified with varying attenuators. Each event was self-triggered with a varying trigger threshold for a total of 100k events.

Figure 1: Standard deviation of the baseline

The red line at a standard deviation of 7 in Figure 1 is the highest baseline standard deviation allowed in the subsequent plots for the unattenuated Am-241 run. The first peak is due to noise in the DAQ board, and the second peak is noise in the baseline due to a bad pulse.

Figure 2: Pulse saturation

The red line in Figure 2 represents the saturation limit of 4500 channels for the pulse amplitude. This pulses used to make this histogram have a baseline standard deviation less than 7.

Figure 3: Pulse maximum amplitude and area

Both histograms in Figure 3 exclude pulses with an amplitude greater than 4500 channels or a baseline standard deviation greater than 7. the histogram of area under the pulse also excludes pulses with a secondary pulse before the main pulse.

Figure 4: Comparison to background.

The background data and dark count data (background with no scintillator) is explained in this post. Figure 4 seems to suggest that we are not seeing the Americium source with the PMT.

Figure 5: Standard deviation of the baseline

The red line at a standard deviation of 7 in Figure 5 is the highest baseline standard deviation allowed in the subsequent plots for the 5x attenuated Am-241 run. The second peak, which represents noisy pulses, has moved much closer to the lower DAQ-noise peak due to the attenuation. This makes it much harder to separate out the bad pulses.

Figure 6: Pulse saturation

The red line in Figure 6 represents the saturation limit of 4500 channels for the pulse amplitude. This pulses used to make this histogram have a baseline standard deviation less than 7.

Figure 7: Pulse maximum amplitude and area

Both histograms in Figure 7 exclude pulses with an amplitude greater than 4500 channels or a baseline standard deviation greater than 7. the histogram of area under the pulse also excludes pulses with a secondary pulse before the main pulse.

Figure 8: Standard deviation of the baseline

The red line at a standard deviation of 6 in Figure 8 is the highest baseline standard deviation allowed in the subsequent plots for the 10x attenuated Am-241 run.

Figure 9: Pulse saturation

The red line in Figure 9 represents the saturation limit of 4500 channels for the pulse amplitude. This pulses used to make this histogram have a baseline standard deviation less than 6. The second peak representing the noisy pulses has been completely swallowed by the noise from the board.

Figure 10: Pulse maximum amplitude and area

Both histograms in Figure 10 exclude pulses with an amplitude greater than 4500 channels or a baseline standard deviation greater than 6. the histogram of area under the pulse also excludes pulses with a secondary pulse before the main pulse.

Figure 11: Comparison to background.

The background data is explained in this post. Figure 11, just like Figure 4, seems to suggest that we are not seeing the Americium source with the PMT.