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s ome investigations on VPT discharges

s ome investigations on VPT discharges. E. Di Marco, A. Ghezzi , D.Petyt , C. Rovelli. t he problem. * we have anomalous energy distributions in the endcaps in some runs * problem spotted also in CRAFT [see past Alessio’s presentations at PFG] Effect: impact on physics. b ad run.

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s ome investigations on VPT discharges

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  1. some investigations on VPT discharges E. Di Marco, A. Ghezzi, D.Petyt, C. Rovelli

  2. the problem • * we have anomalous energy distributions in the endcaps in some runs • * problem spotted also in CRAFT [see past Alessio’s presentations at PFG] • Effect: impact on physics bad run good run jet/met DQM: jet eta distribution

  3. ex. run 122490 * closer look to the first part (250000 events) of run 122490 – with anomalous distribution in DQM * look for events with at least 1 channel with amplitude (cosmicsreco) > 500 ADC * 29 events found, only 2 crystals involved: Ix = 45, Iy = 1, Iz = -1 found in 15 events Ix = 81, Iy = 55, Iz = -1 found in 13 events not problematic in health checks and standard cosmics running no other crystal with large (>100 ADC) energy deposit in those 29 events

  4. crystal 45-1-m1 amplitude * bad amplitude * bad pedestal online * bad chi2 in few events perfect behaviour in other events only 8/15 events; others: chi2=0 pedestal chi2

  5. crystal 81-55-m1 amplitude * bad amplitude * bad pedestal online * bad chi2 in few events perfect behaviour in other events pedestal chi2

  6. random events does not happen in the same events on the two channels not restricted to a small run fraction [consistent with discharges hypothesis]

  7. not firing SPR * large energy deposit (>500 ADC) but the SRP does not start [spotted by Toyoko as well] -- > problem! * S1/S9 can not be computed (but others zero suppressed -> ~1)

  8. when? where? • Checked DQM data (in WBM) to search for any EE channel with RMS>6.0 • Extended the search back to CRAFT 09 • – run range used: 108265 (23rd Jul) to 123060 (30th Nov) • Used a sub-sample of ~100 runs taken during this period • Used online pedestal (pre-samples from cosmic events) and pedestal events taken in • calibration sequence • Found 53 channels with online pedestal RMS>6. Their location and frequency are on the next slide

  9. Location of noisy channels Number of runs with RMS>6 Alessio’s channels

  10. Noisy channel list Some persistently noisy channels. Others appear in just 1-2 runs Known noisy channels 12 channels with RMS>10, which are noisy in recent data, and for more than 1 run

  11. History plots – very noisy channels Very similar patterns seen What happened between 24-25 Nov? (no obvious clues in ELOG)

  12. Noisy channels during CRAFT Several channels become very noisy around 20th August… Noise re-appears on 24/25 Nov… Some channels become noisy again in recent data

  13. Different noise patterns Many channels show noisy behaviour in these two “bursts”: a) (CRAFT09 after 20th Aug); b) 24-25th Nov However, a few other channels show different time patterns…

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