Attempts to find photoelectron peaks

SiPM 4 and a blue LED were tested with a 1.487kOhm resistor in the dark-box in order to see if a lower light intensity would allow the photoelectron peaks to be resolved. There are two runs that are identical except for the number of events taken. Data file 130626_blueLED_ext-trig_10Hz_100ns_1.487kOhm.dat has 10k events (short), and 130626_blueLED_ext-trig_10Hz_100ns_1.487kOhm_x10.dat has 100k events (long). Both runs are externally triggered.

Figure 1: The area under the pulse for each run individually and combined.

Figure 2: The pulse maximums for each run individually and combined.

The histograms of the pulse areas (Figure 1) only used pulses with a baseline standard deviation less than 43 and no secondary pulses present. The histograms of the pulse maximums (Figure 2) only used pulses with a baseline standard deviation less than 43.

The photoelectron peaks are still not present in either set of histograms.

Another attempt to resolve photoelectron peaks was conducted with a higher gain. The bias voltage on SiPM 4 was raised from 20.6V to 21.5V. This should increase the channel-separation between photoelectron peaks. This test was conduced using a blue LED with a 1.487 kOhm resistor in the dark-box. The SiPM was externally triggered and had 100k events. The data file for this run is 130627_blueLED_ext-trig_10hz_100ns_x10_bias3800.dat.

Figure 3: The pulse area and maximum for the higher bias voltage run.

The histograms for the run with the higher bias voltage (Figure 3) only include pulses with a baseline standard deviation less than 53. The pulse area histogram (Figure 3a) also does not include pulses with a secondary pulse present.

The photoelectron peaks are still not present in this set of histograms.

A third attempt to resolve photoelectron peaks was done by changing SiPMs. SiPM 3 was run with the bias voltage back at 20.6V and with the blue LED with a 1.487 kOhm resistor in the dark box. This run was externally triggered and had 100k events. The data file for this run is 130628_blueLED_ext-trig_10hz_100ns_1.487kOhm_x10.dat.

Figure 4: The pulse area and maximum for SiPM 3.

The histograms for the run with SiPM 3 (Figure 4) only include pulses with a baseline standard deviation less than 45. The pulse area histogram (Figure 4a) also does not include pulses with a secondary pulse present.

This run was successful because photoelectron peaks are visible in the histogram of the pulse area (Figure 4a).