Start Counter Operations
Start Counter Operations
Start Counter Response
Performance studies of the start counter over time. As is shown in plots below in terms of the response of the start counter paddle to hits in the nose cone is much stronger (yielding more photons) than in the straight section. Also, there is not much of a variation seen in the response for hits along the straight section. However, the mean detector response did degrade over time over the full length of the individual paddles. In general the mean detector signal peak in the strait section degraded from about 400 ADC counts in Run Period 40k to about 200 ADC counts in Run Period 120k with a larger variation from paddle to paddle. Similarly, the response in the nose section degraded too, where the degradation is also seen to be abut a factor of 2. To illustrate this finding two plots are shown below of the mean Start counter response as a function of z position along the paddle (in units of "bins") for run 41388 and run 120848:
Plots of Start Counter response
- Detector response as a function of z location over time. The z-bin starts with 60cm and each bin covers 2cm so bin 2 is 62-64 cm and bin 17 is 84-86 cm. As an example paddle 3 bin 7 and bin 15 are compared between run 41835 and run 90660. It is clear that in the nose section (bin 15) the response is much larger (meaning more photons reach the SiPM)