Detector 9 anneal 2012

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Revision as of 23:29, 17 March 2014

Notes

Some "historical record searching" has revealed that noisy intervals have occasionally shown up in D9 ever since the March 2010 anomaly. It is not clear that these were associated in any way with the anomaly, but no instances have been found before it. These noisy intervals are easiest to see in the rear slow monitor rates or rear event rates. See a presentation (2013-04-17_Detector_9_weirdness) by Albert Shih for more info.

• 15 Feb 2012: Final stages of the anneal, all detectors, are back to 4000 V, except for detector 9 (which showed some arcing after SAA passages).

• 7 - 14 March 2012: Some noise was observed on detector 9. On March 8 at 01:24 UTC detector G9 HV was lowered by ten counts. Some sporadic noise was observed, but the detector appears to fixed it-self.

• 11 - 18 April 2012:
  • Rear fast threshold from 0x45 -> 0x60
    • /IDPUDUMPTABL DIBTBL9
    • /IDPUTABLE9 REARFASTDAC  ;Load address 0x262C
    • /IDPULOAD VALUE=0x60  ;Byte 10, Rear Fast threshold

• March 4-19, 2013, March 29-April 11, 2013: Noise on D9; see Tohban_Report_2013-04-17 for more info.

• May 3-7+ 2013: Noise is back on D9. Once again, it's occasional short intervals (a few minutes) of noise in the event rates. This usually shows up as dropouts in the rear slow monitor rate plots. The occurrences this week were short and not severe. They happened around the following times:

 May 7: 11:09
 May 6: 11:19, 9:42
 May 5: 9:54, 1130
 May 4: 1937, 1803, 1625, 1004
 May 3: 1152, 1015

No action was taken since the problem was not severe. See more notes in the Tohban_Report_2013-05-08 tohban report.

• The D9 dropouts returned the week of Sept 4 - 11, 2013.

 They began in short and non-severe dropouts on the 4th. By the 9th, their duration and severity increased to a maximum before beginning to
 wane again on the 10th. 

No action was taken since their severity and frequency was comparable to those seen in the past, and there were no consequences to livetime or SSR.

• 11-Jan-2014: The D9 rear fast LLD threshold was raised from 0x60 to 0x70 at 07:01:37 UTC.

• 24-Jan-2014: The D9 rear fast LLD threshold was raised from 0x70 to 0x80 at 00:53:41 UTC.

• 28-Jan-2014: The D9 front fast LLD threshold was raised from 0x22 to 0x30 at 22:13 UTC.

• 29-Jan-2014: The D9 front fast LLD threshold was raised from 0x30 to 0x40 at 22:11 UTC.

• 15-Feb-2014: Around this time, fast rates for D8 and D9 rose, and became very high for the next several days. The D8 behavior may be pickup of noise in D9. On Feb 27 a test will be conducted to see if temporarily lowering the D9 HV fixes the problems in both.

• 05-Mar-2014: HV commanding on D9r: The experimental decrease of D9 voltage yielded confusing results. The voltage reduction surprisingly increased the reset rates ( ~6500 to ~9000) in D9 without any noticeable change to D8. There was no issue when we lowered/raised HV on D9, and the reset rates returned to ~6500. It was decided to simply raise the thresholds on D6f, D8r and D9r. D9r threshold change: This also yielded confusing results when D9 rear fast valids shot up (10,000 --> 50,000) as a result of the increased threshold. Over the intervening week, the D9 rear fast valids have slowly come back down to ~5,000 with no additional commanding. The G9 rear fast LLD was changed 0x80 to 0x90 at 2014/058 19:25 UTC.

D9 front slow LLD threshold history

D9 front fast LLD threshold history

D9 rear slow LLD threshold history

D9 rear fast LLD threshold history