Determining effect of varying the attenuation resistor

Pulse area and Maximum Histograms

The blue LED was run with increasingly strong resistors with SiPM 4 in the dark-box. Each event was externally triggered and delayed by 400 ns. Each data file contains 10k events.

Table 1: Resistances used and the data file for each run.
Run	Resistance	Data file
1	1.693 kOhm	130711_sipm4_blueled_delayed-trig_1.693kohm.dat
2	1.750 kOhm	130711_sipm4_blueled_delayed-trig_1.750kohm.dat
3	1.807 kOhm	130711_sipm4_blueled_delayed-trig_1.807kohm.dat
4	1.838 kOhm	130711_sipm4_blueled_delayed-trig_1.838kohm.dat
5	1.906 kOhm	130711_sipm4_blueled_delayed-trig_1.906kohm.dat
6	1.963 kOhm	130711_sipm4_blueled_delayed-trig_1.963kohm.dat
7	2.00 kOhm	130715_sipm4_blueled_delayed-trig_2.00kohm.dat

Figure 1: Pulse area and maximum for 1.693 kOhm resistor.

Figure 2: Pulse area and maximum for 1.750 kOhm resistor.

The photoelectron peaks are not visible enough in the first two resistances (Figures 1 and 2) for further calculations.

Figure 3: Pulse area and maximum for 1.807 kOhm resistor.

Figure 4: Pulse area and maximum for 1.838 kOhm resistor.

Figure 5: Pulse area and maximum for 1.906 kOhm resistor.

Figure 6: Pulse area and maximum for 1.963 kOhm resistor.

Figure 7: Pulse area and maximum for 2.00 kOhm resistor.

Table 2: The above histograms exclude pulses with a baseline standard deviation greater than what is listed here.
Run	Resistance	Baseline standard deviation
1	1.693 kOhm	23
2	1.750 kOhm	23
3	1.807 kOhm	22
4	1.838 kOhm	23
5	1.906 kOhm	22
6	1.963 kOhm	23
7	2.00 kOhm	23

All histograms of pulse area also exclude any events with a secondary pulse.

Weighted average number of photoelectrons

The weighted average number of photoelectrons for each attenuation resistance (excluding the two with photoelectron peaks of low visibility) was calculated a plotted against the attenuation resistance of that run. This is plotted in Figure 7.

Table 3: Weighted average number of photoelectrons for each resistance.
Resistance	Average number of photoelectrons
1.807 kOhms	3.41
1.838 kOhms	3.33
1.906 kOhms	2.10
1.963 kOhms	1.56
2.00 kOhms	1.12

Figure 7: LED attenuation resistance vs. average number of photoelectrons.

Poisson Fitting

Figure 8: Photoelectron peaks from the 1.807 kOhm resistor fit to a Poisson distribution.

Figure 9: Photoelectron peaks from the 1.838 kOhm resistor fit to a Poisson distribution.

Figure 10: Photoelectron peaks from the 1.906 kOhm resistor fit to a Poisson distribution.

Figure 11: Photoelectron peaks from the 1.963 kOhm resistor fit to a Poisson distribution.

Figure 12: Photoelectron peaks from the 2.00 kOhm resistor fit to a Poisson distribution.

Table 4: Results of the poisson fit for each resistor.
Resistance	Average number of photoelectrons	Chi-squared
1.807 kOhm	3.63	6670.95
1.838 kOhm	3.53	6738.77
1.906 kOhm	2.34	16818.8
1.963 kOhm	1.85	55266.7
2.00 kOhm	1.46	-

There is no chi-squared for the poisson fit of the 2.00 kOhm data because there were too few point in its graph (Figure 12).

Figure 13: Resistance vs. Average number of photoelectrons.