21/02/15

1230: Developing the software to check synchronisation between DAQs. Below line runs program on aidas1 - sends data from TapeServer to BELEN.

            ./DataRelayFilter -n 10.32.6.196 -p 10307 -I 2

1500: Investigating pulser peak FWHMs as function of bias voltage.

           Constant shaping time of 0x3, slow comp thresh 0x20, fast comp thresholds of 0xff. All other setting as standard. Detector MSL BB18 2977-20.

           Results summarised in table directly below.

             At bias of -200V nnaida1+6 stopped outputting data but continued to produce SYNCs. Good event rate dropped from ~few thousand per sec to ~300 per sec.

             After returning bias to -150V, nnaida1+6 started producing data again. No effect was seen in nnaida3+8.

             nnaida8 peaks are not particularly Gaussian in shape. Look more skewed with one rolling edge and one side a relatively sharp drop.

            No obvious trends with changing bias voltage. Will return to -100V.

1545: Investigating pulser peak FWHMs as function of shaping time.

           Bias returned to -100V, with leakage current 11.000uA.

           Settings for all nnaida: slow comp thresh = 0x20, fast comp thresh = 0xff, hold time = 0x4 if shaping time <= 0x8, 0x8 if shaping time > 0x8.

           Visual 'analysis' suggested 0xb to be the optimal value so used that as shaping time in further tests.

           (Graph to follow)

1900: Investigating effect of changes to slow comparator thresholds.

           Settings: bias = -100V, hold timing = 0x8, shaping time = 0xb, fast comp thresholds = 0xff. Otherwise, standard settings.

          With threshold at 0xd, threshold position was very hard to determine for nnaida6+8, assume discirminator is running in the noise. Will ignore data for 0xd.

          Assuming central position of 32768 and energy per channel of 0.7 keV, below table gives approximate position of threshold in keV.

           Thus (very roughly), between 0x10 and 0x20, the above table shows the threshold moving by about 10 keV per increment in the threshold.

           With the threshold at 0x10, the data rate show on the TapeServer window was ~3Mb/s (uncompressed?).

           This was with 1 detector (BB18 2977-20) connected to 4 FEE64s with above settings, a 25Hz pulser and 241Am+207Bi sources (activities in ELog entry 40).

           The Good Events rate averaged around 30,000-60,000/s per FEE64 card, with only a few Pause/Resumes coming through.

           Example stats screen and hit patterns included below for final configuration.