Performed pulser measurements with test setup at Daresbury lab, with main purpose of remembering how to operate the system! The status is similar to what Chris observed in Elog entry #14. Confirmed ASIC settings as in entry#4 of elog.
The pulser spectra shows FWHM of ~ 13.5 ch for all FEE64 cards with no DSSD connected to the system (i.e. Kapton cables unplugged). Some channels in a few FEE64 cards show two peaks on the pulse spectra, but still narrow and only slightly wider distribution for the two peak combined (~ 15 ch, see Figure 1).
With the DSSD connected, the pulser spectra shows a double peak structure with FWHM ~ 250 ch for each peak (Figure 2).
However, for NNAIDA#11 and #12 a few ASICs had high level of noise, and were therefore used in the 1GeV range to become quiet (ASIC3 for nnaida#11, ASIC1 and 2 for nnaida#12). Figure 3 and 4 show sample of these noisy channels.
A good question brought up by Patrick is if the true noise level with a biased DSSD corresponds to these 'noisy' ASICs, or to the ones that are much more quiet (maybe some signal path disconnected for these?). Measurements with a radioactive source could clarify this.
Figure 1: pulser, no DSSD connected
Figure 2: double peak structure for pulser spectra for NNAIDA13 (similar spectra seen in the other FEE64 cards)
Figure 3: spectra for NNAIDA#11 with biased DSSD connected, and no pulser signal going into the system (only noise)
Figure 4: spectra for NNAIDA#12 with biased DSSD connected, and no pulser signal going into the system (only noise)
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