Dark count dependence on temperature

The dark count rate depends on temperature. We use a peltier element and a dark box to quantify this relationship.

Setup

@Vikas: can you update this?

Measurements

We took dark count measurements at 12 different temperatures.

T = [9.565, 7.664, 1.915, 3.823, 11.484, 5.735, 17.256, 15.32, 13.405, 19.185, 21] degrees Celcius.

For each temperature, around 1500 waveforms were recorded with an oscilloscope. Each waveform is 5 microseconds. You can clearly see the single p.e. peaks already in the raw waveform shown in Figure 1. In Figure 2, a waveform with electronic noise is shown. For 9 degrees Celcius, we have only a few waveforms available.

Figure 1: Raw waveform at 13 degrees.

Analysis

For each temperature, we count the peaks in each recorded waveform. Because there is a lot of high-frequency noise on top of the signal, we low-pass filter the signals before peakfinding. The result is shown in Figure 3 for the signal in Figure 2. Even though there is noise, the filtering and peak finding steps manage to identify the correct signal peaks. In Figure 3, we count 7 peaks. Figure 4 shows a histogram of counts for all 1500 waveforms for 1 degree Celcius. The distribution resembles a Poisson distribution fairly well. Therefore, we can use Poisson statistics to calculate the uncertainty.

Conclusions

Figure 2: Raw waveform at 13 degrees showing noise.

Figure 3: In blue the raw data, which is also in Figure 2. In orange the low-pass filtered data, and in red the peaks.

Figure 4: Histogram of the counts for all 1500 waveforms for 1 degree Celcius. In orange a Poisson distribution is shown with the same average as the blue histogram. The two distributions are similar.