Detector 8 anneal 2012

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Revision as of 19:21, 11 April 2014

July 24 2012: Due to an excess of low energy counts coming out of the SAA, the HV on detector 8 was lowered by 5 steps, from 193 to 188 at 20:25 UT. This reduced, but did not eliminate, the excessive counts. Since the noisy count rates were not so high that memory fill or livetime were compromised, no further voltage reductions were taken at this time.

24 October 2012: The HV was lowered by 5 counts on at 21:09UT. The voltage now sits at 3455.9 V

5 November 2012: The HV was lowered by 5 steps from 3456 V to 3358 V at 2012-310-19:31:18 and another 5 steps to 3260 V at 2012-310-21:10:52.

2012 December 12: D8's decay coming out of the SAA has greatly increased over the past week. In some cases, its decay extends through the entire following orbit. These elevated counts filled the SSR to ~70% and would only allow it to empty to ~40%. For the time being, the D8 counts are not being stored in an effort to empty the SSR. D8 voltage was lowered by 10 steps to try an alleviate the issue, but it has not done so. We will try lowering the voltage incrementally, by 10 steps, until the problem abates.

2012 December 19: The noise in D8 was determined to go up to hundreds of keV. The voltage was stepped down by 10 steps on Dec. 14 and again on Dec. 17 (days of year 349 and 352), leaving the voltage at 2617.6V. D8 events remained off this week.

2012 December 26: D8's voltage was stepped down another 10 steps on Dec. 21 (DOY 356) to 2475.5V. This finally brought down the noise, which is now not present even coming out of the SAA. The last easily noticeable noise in the rates was recorded on Dec. 19. Detector 8 events will soon be turned back on.

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: G8 rear fast LLD was changed from 0x45 to 0x60D on 2014/058 19:25 UTC. fast valids dramatically decreased from 100,000 --> 1,000 counts. Within the past week its drifted back up to ~5,000 counts.

2014 March 10: D8 rear fast threshold was changed from 0x60 to 0x70 at 2014-070-03:00 UTC due to decreased livetime down to 80%. The livetime immediately recovered to 97%.

2014 March 18: D8's rear fast threshold was raised again, this time to 0x80. Commanding was at 23:31:31.

   14-080-23:01:58 /IDPUTABLE8 REARFASTDAC
   14-080-23:02:16 /IDPULOAD VALUE=0x90

   14-086-18:18:15  /IDPUTABLE8 REARFASTDAC
   14-086-18:18:24  /IDPULOAD VALUE=0xA0

   14-097-17:11:51 /IDPUTABLE8 REARFASTDAC
   14-097-17:12:14 /IDPULOAD VALUE=0xB0

2014 Apr 10: D8 rear fast threshold was raised again (because, even after the change on Apr 7, the livetime continued to decrease rapidly down to 5%).

   14-100-18:10:59 /IDPUTABLE8 REARFASTDAC
   14-100-18:11:12 /IDPULOAD VALUE=0xC0

2014 Apr 11: D8 rear fast threshold was raised again (because the livetime recovered up to only 50% after the previous threshold change).

   14-101-17:55:41 /IDPUTABLE8 REARFASTDAC
   14-101-17:55:52 /IDPULOAD VALUE=0xD0

post 2012 anneal	0x0C

post 2012 anneal	0x22

post 2012 anneal	0x30