From RHESSI Wiki
This page contains information about changes/issues for RHESSI detector 9 after the 2014 anneal. Detector updates from 2012-mid 2014 can be found here: Detector 9 anneal 2012
Post 2014 Anneal
Detector 9 is SEGMENTED after the 2014 anneal!
- 2014 August 20: Due to sporadic noise in D9, the HV was dropped by 20 counts (now at 3600V). Commanding was at 20:57 UTC. This successfully quieted the noise. The noise was mainly fast counts, which cut drastically into the livetime.
- 2014 October 8: This detector has started to show some periodical spikes during last couple of days. Still is not clear what is their origin. It seems to be periodic with the orbit. So far no action taken.
- 2014 Oct 31: Elevated noise during the period of Oct 31 - Nov 2. The onset, as well as the abatement was sudden. No commanding was done and the noise returned to regular levels.
- On 2015 Jan 8, the rear fast threshold was raised since fast counts were eating up a lot of livetime.
15-008-17:45:50 /IDPUTABLE9 OFFSET=REARFASTDAC
15-008-17:46:04 /IDPULOAD VALUE=0x50 ;(was 0x45)
- Rear fast counts are high again, so we raised the rear fast threshold by 16 steps, in two sets of 8, on the BGS pass starting at ~3:30 PST. The new value is 0x60 (was 0x50). Fast rates as eyeballed from the realtime data were approx 58,000 (pre-adjustment), 12,000 (after 8 steps up), and 1600 (after 16 steps up). Livetime percentages were approx 60%, 90%, and 98%, respectively.
15-021-23:33:58 /idpudumptabl table=dibtbl9
15-021-23:34:03 /idputable9 offset=rearfastdac
15-021-23:34:34 /idpuload value=0x58
15-021-23:36:47 /idputable9 offset=rearfastdac
15-021-23:36:55 /idpuload value=0x60
- The rear fast threshold was raised again for the same reasons as the last two adjustments. The threshold was raised in two jumps of hex 8 each.
15-057-18:43:13 /IDPUTABLE9 OFFSET=rearfastDAC
15-057-18:45:14 /IDPLOAD VALUE=0x68
15-057-20:21:52 /IDPUTABLE9 OFFSET=REARFASTDAC
15-057-20:22:09 /IDPLOAD VALUE=0x70
- Rear fast threshold changed again, usual reason.
15-064-19:39:50 /IDPUTABLE9 OFFSET=REARFASTDAC
15-064-19:40:12 /IDPLOAD VALUE=0x80 ; was 0x70
- And again, on March 11, 2015.
2015-070-22:46:04 /IDPUTABLE9 OFFSET=REARFASTDAC
2015-070-22:46:19 /IDPLOAD VALUE=0x90
- On March 13, 2015 the rear fast threshold was changed again
15-072-22:06:18 /IDPUTABLE9 OFFSET=REARFASTDAC
15-072-22:06:31 /IDPLOAD VALUE=0xA0
- And then again, on March 16, 2015.
15-075-19:24:13 /IDPUTABLE9 OFFSET=REARFASTDAC
15-075-19:24:28 /IDPLOAD VALUE=0xB0
- And then again, on March 18, 2015.
15-077-TBD /IDPUTABLE9 OFFSET=REARFASTDAC
15-077-TBD /IDPLOAD VALUE=0xC0
- And again, on March 25, 2015.
15-084-21:07:00 /IDPUTABLE9 OFFSET=REARFASTDAC
15-084-21:07:14 /IDPLOAD VALUE=0xFF
- In addition we change the HV on March 25, 2015:
15-084-19:26:07 /ihvdac detector=9, voltage=176
15-084-19:27:17 /ihvdac detector=9, voltage=166
15-084-19:28:33 /ihvdac detector=9, voltage=156
15-084-21:05:17 /ihvdac detector=9, voltage=136 (2622 V)
- As of early April, detector 9 rear segment is now essentially non functional. Rear fast rates have increased to the point where livetime dropped to zero, and the fast threshold is already turned all the way up so we have no way to control those rates. The front segment appears to be operating normally, though its fast AND slow rates are high (but not worringly so).
- 2015 April 7: To deal with slightly reduced livetime in the FRONT segment, we changed the front fast threshold. This does NOT seem to have had an effect!!
15-097-19:58:06 /IDPUTABLE9 OFFSET=FRONTFASTDAC
15-097-19:58:14 /IDPLOAD VALUE=0x30 ; was 0x22
- 2015 April 14: We increase the Front Slow Threshold just to reduce the values on the front slow valid counts
15-104-14:09:00 /IDPUTABLE9 OFFSET=FRONTSLOWDAC
15-104-14:09:12 /IDPLOAD VALUE=0x1A
- 2015 May 13: D9 front fast was increased
2015-133-19:09:39 /IDPUTABLE9 OFFSET=FRONTFASTDAC
2015-133-19:09:52 /IDPLOAD VALUE=0x40 ; was 0x30
- On June 11 2015 the front fast threshold was raised because the fast rates were high and the livetime was low. This action was DID reduce the fast rates but did NOT increase the livetime much! D9 now does not show high fast rates, slow rates, or resets, but yet the livetime is quite low.
- On August 20 2015 the front fast threshold was raised in an attempt to gain livetime, which was at ~15%. This was unsuccessful.
15-232-22:21:09 start idib_chg_thrshld (9, FRONT, FAST, 0x90)
15-232-22:21:38 /IDPUDUMPTABL TABLE=DIBTBL9
15-232-22:21:38 /IDPUTABLE9 OFFSET=FRONTFASTDAC
15-232-22:21:46 /IDPLOAD VALUE=0x90
- On August 20 2015 the rear segment started dumping a huge number of ULD events into the SSR, filling it. Once the problem was pinpointed, D9 events were disabled entirely on the 21st. D9 HV was turned down to 1800V, then 900V, then 800V, in an attempt to bring down the resets. This brought resets down from 30k to 23k and did, indeed, quiet the ULDs. The detector remained segmented. At one point the threshold change to D9 front was reversed to see if that had caused the problem (it hadn't); the threshold change was then re-implemented. Events were turned briefly back on on Aug. 24 and then off, although no danger signs were seen. As of Aug. 25, D9 events are still off. Approximate commanding times are below:
1:15 pm PDT: D9 front fast threshold to 0x60 (was 0x90).
2:50 pm PDT: D9 front and rear events disabled.
4:30 pm PDT: HV drop of ~400V, performed in two steps, to 1838V. No change to resets (30k). RTS load to keep D9 events from being re-enabled after eclipse. D9 fast and slow thresholds to max.
6:00 pm PDT: HV drop to ~900V and then again to ~800V. Rear resets before and after are 30k then 25.7k then 23.5k. D9 front fast threshold returned to 0x90.
- On August 24 2015 D9 events were enabled at 20:42:45 UTC in order to check whether we would still dump too many events into the SSR. The write pointer speed didn't seem to change with this action (although it maybe did change with other detector threshold changes). We left D9 events on, knowing that they'd be turned off again at the next dawn due to the RTS load. As of Aug. 26, D9 events are still off.
2015-236-20:42:45 /itmon value=AFE8 (Detector 9 events turn on)
- On Sept 9-11, 2015, the rear D9 ULD rose, finally going crazy and maxing out on Sept 11. Since events were off, this wasn't noticed until Sept. 28. To try and avoid/mitigate potential damage to the detector, we lowered the HV on D9 on Sept. 29 PDT (Sept. 30 03:00 UTC) from ~800V to 490V. We briefly turned on events for G9 as well. Events were then turned off again at eclipse entry. The ULD event rate should be checked as soon as we get the monitor rate data on it. The detector stayed segmented.
2015-273-03:00:43 /itmon value=AFE8 (Detector 9 events on)
2015-273-03:01:09 /IHVDAC DETECTOR=9, VOLTAGE=26
- D9 ULDs went haywire again, so we decided to turn off the HV and electronics for D9. On Oct 13 Jeremy removed all power from detector 9's HV and turned off DIB (Detector Interface Board) 9. This commanding was done October 13, 2015 at 18:22 UTC. It should be monitored to see if we get any noticeable changes to power or temperature diagnostics due to this.
2015-286-18:21:43 /IHVDAC DETECTOR=9, VOLTAGE=0
2015-286-18:22:48 start idib_single_off(9)
Post 2016 Anneal
- D9 HV ramped up to 4000 V. The detector was segmented around 1700 V. We adjusted the rear fast threshold up from 0x45 to 0x60 then turned on events.
D9 front slow LLD threshold history
| post 2014 anneal || 0x0C
| 2015 Apr 14 14:09:12 || 0x1A (was 0x0C)
D9 front fast LLD threshold history
| post 2014 anneal || 0x22
| 2015-Apr-07 19:58 || 0x30 (was 0x22)
| 2015-May-13 19:09:52 || 0x40 (was 0x30)
| 2015-Jun-11 20:18:44 || 0x50 (was 0x40)
| 2015-Jul-31 21:42:36 || 0x60 (was 0x50)
| 2015-Aug-20 22:21:46 || 0x90 (was 0x60)
| 2015-Aug-21 ~20:15 || 0x60 (was 0x90)
| 2015-Aug-22 ~01:15 || 0x90 (was 0x60)
D9 rear slow LLD threshold history
| post 2014 anneal || 0x30
| 2015-Aug-22 ~1:15 UTC || 0xFF
D9 rear fast LLD threshold history
| post 2014 anneal || 0x45
| 2015-Jan-08 17:46:04 || 0x50 (was 0x45)
| 2015-Jan-22 23:34:34 || 0x58 (was 0x50)
| 2015-Jan-22 23:36:55 || 0x60 (was 0x58)
| 2015-Feb-27 18:45:14 || 0x68 (was 0x60)
| 2015-Feb-27 20:22:09 || 0x70 (was 0x68)
| 2015-Mar-05 19:40:12 || 0x80 (was 0x70)
| 2015-Mar-11 22:46:19 || 0x90 (was 0x80)
| 2015-Mar-13 22:06:31 || 0xA0 (was 0x90)
| 2015-Mar-16 19:24:28 || 0xB0 (was 0xA0)
| 2015-Mar-18 21:52:57 || 0xC0 (was 0xB0)
| 2015-Mar-18 23:32:15 || 0xD0 (was 0xC0)
| 2015-Mar-25 21:07:00 || 0xFF (was 0xD0)
| post 2016 anneal || 0x60
D9 HV history
| post 2014 anneal || 3995 V
| 2014-Aug-20 || 3603V (was 3995V)
| 2015-Mar-25 || 2622V (was 3603V)
| 2015-Aug-03 || 2230V (was 2622V)
| 2015-Aug-21 || ~2000V (was 2230V)
| 2015-Aug-21 || ~1800V
| 2015-Aug-21 || ~900V
| 2015-Aug-21 || 808V
| 2015-Sep-30 03:01:09 || 490V (was 808V)
| 2015-Oct-13 18:22:48 || 0V
| post 2016 anneal || 3995 V