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User name adaq
Log entry time 17:12:03 on November 4,2010
Entry number 338468
This entry is a followup to: 338444
keyword=Helicity checks IIRuns 8316 and 8317 are taken with the LHRs only config and triggered by the TSettle (once per helicity window). The helicity flipping rate was 120 Hz. The goal was to check if the suprious readings we have in the scaler ring also appear in the input register (TIR). I have analyzed in some details run 8316. The conclusion is that the helicity stream recorded by the TIR are ok, this is consistent with for example the Compton DAQ not complaining about something being wrong with the helicity control signals it uses. But something is definitively fishy in the scaler ring, we still do not know what More to follow tomorrow. One of Bob Micheal's idea would be plug the signals recorded in the ring in a scaler (in plus of in the ring); this should allow to conclude on double pulsing.
Some more details.
Plot 1 shows that the helicity can be predicted reliably throughout once we have recorded 30 of them in a row (nseed =30, see bottom plot of figure 1) . The only thing that looks trange on the TIR signals is the time between two signals, it should be quite a fixed value but actuallythe value changes a bit (top plot of figure 1). I do believ the clock there is 103.7 kHz, so that would give a helcity window fluctuating by +/-60 channels=0.5 ms.
Plot 2 shows the data on the ring side. When triggering on Tsettle, one should only record on event in the ring. The data show that for some TR events, we have up to 12 events in the ring, that's no good. The top plot of figure 2 shows along the vertical axis the number of event in the ring per each TIR reading. The horizontal axis shows the time elapsed between two ring readings. So the extra events are recorded very quickly one after each other. At first we though that the trigger for the ring (Load Next Event) might be multi-pulsing. Unfortunatly, the info recorded in the ring is not a pure repeat of itself, the data do change as shown in the lines below:
nevt is the main event (tir)
iring is the number of the sclaer ring reading for a given TIR event (should always be 0).
hring is the helicity recorded for a given scaler ring event, qrtring is the quarter start signal (Patternsync).
Note how for nevt=130, the ring returns 6 events with "random" helcity and quarter start signals (Patternsync).
************************************************************
* 2929 * 130 * 0 * 0 * 0 *
* 2930 * 130 * 1 * 0 * 0 *
* 2931 * 130 * 2 * 0 * 0 *
* 2932 * 130 * 3 * 1 * 0 *
* 2933 * 130 * 4 * 0 * 0 *
* 2934 * 130 * 5 * 0 * 0 *
* 2935 * 130 * 6 * 1 * 1 *
* 2936 * 131 * 0 * 0 * 0 *
* 2937 * 132 * 0 * 0 * 0 *
* 2938 * 133 * 0 * 0 * 0 *
* 2939 * 134 * 0 * 0 * 0 *
* 2940 * 135 * 0 * 1 * 0 *
* 2941 * 135 * 1 * 0 * 0 *
* 2942 * 135 * 2 * 0 * 0 *
* 2943 * 135 * 3 * 0 * 1 *
* 2944 * 135 * 4 * 0 * 0 *
* 2945 * 135 * 5 * 0 * 0 *
FIGURE 1
FIGURE 2
