Detector 4

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This page contains information about changes/issues for RHESSI detector 4 after the 2014 anneal. Detector updates from 2012-mid 2014 can be found here: Detector 4 anneal 2012

Post 2014 Anneal

After the 2014 anneal, detector 4 is UNSEGMENTED.

  • On May 21 starting at 19:24 UTC we raised up the Slow threshold for the Front segment.
15-141-19:24:10 start idib_chg_thrshld (4, FRONT, SLOW, 0x68)  --> Was 0x60
15-141-19:24:22 /IDPUDUMPTABL TABLE=DIBTBL4
15-141-19:24:22 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
15-141-19:24:31 /IDPLOAD VALUE=0x68
  • Raised front fast threshold due to elevated counts. This change reduced counts and increased livetime
2015-152-17:00:18 /IDPUTABLE4 OFFSET=FRONTFASTDAC
2015-152-17:00:31 /IDPLOAD VALUE=0x60  ; was 0x50
  • On 2015 July 7, D4 front fast threshold was raised due to decreased livetime.
2015-188-18:48:17 /IDPUTABLE4 OFFSET=FRONTFASTDAC
2015-188-18:48:34 /IDPLOAD VALUE=0x70  ; was 0x60
  • The front fast threshold was increased on July 10 2015 due to low livetime due to high fast rates. This action was effective in raising the livetime.
2015-191-19:21:17 /IDPUTABLE4 OFFSET=FRONTFASTDAC
2015-191-19:21:25 /IDPLOAD VALUE=0x80  ; was 0x70
  • The front fast threshold was increased on July 24 2015 due to low livetime due to high fast rates. This action was effective in raising the livetime, to ~90%.
2015-205-17:22:21 /IDPUTABLE4 OFFSET=FRONTFASTDAC
2015-205-17:22:30 /IDPLOAD VALUE=0x90  ; was 0x80
  • 2015-08-13: Front slow valid threshold was raised by 10 steps; trying to get the slow valid rates down.
 2015-225-16:45:08 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
 2015-225-16:45:20 /IDPLOAD VALUE=0x80  ; was 0x70
  • On Aug 20, 2015 the front fast threshold was raised, in two commands of 16 steps each, in order to lower fast rates and free up livetime. This was successful but probably needs to be repeated. Livetime rose from ~0% to ~50%. The D4 threshold should be raised again to further raise the livetime.
15-232-22:17:53 start idib_chg_thrshld (4, FRONT, FAST, 0xA0)
15-232-22:18:12 /IDPUDUMPTABL TABLE=DIBTBL4
15-232-22:18:12 /IDPUTABLE4 OFFSET=FRONTFASTDAC
15-232-22:18:25 /IDPLOAD VALUE=0xA0

15-232-22:19:13 start idib_chg_thrshld (4, FRONT, FAST, 0xB0)
15-232-22:19:23 /IDPUDUMPTABL TABLE=DIBTBL4
15-232-22:19:23 /IDPUTABLE4 OFFSET=FRONTFASTDAC
15-232-22:19:32 /IDPLOAD VALUE=0xB0
  • On Aug 24, 2015 the front fast threshold was raised twice to free up livetime. This was successful. Note that these changes are working, but we're almost out of head room!
2015-236-20:44:08 /IDPUTABLE4 OFFSET=FRONTFASTDAC
2015-236-20:44:22 /IDPLOAD VALUE=0xD0  ; was 0xB0

2015-237-00:02:14 /IDPUTABLE4 OFFSET=FRONTFASTDAC
2015-237-00:02:22 /IDPLOAD VALUE=0xE0 ;  was 0xD0
  • As was discussed during the last meeting, detector 4 showed elevated slow front rates. Following the suggestions of the previous tohban, on August 27 the slow front threshold was increased but no change was observed at all. As the front fast rates were also elevated, a change in the front fast threshold was performed. This change increased its livetimes and the slow front rates, as was expected. Then we decrease D4 HV by 200V, a very conservative value as we would like the detector to segment. However the HV change did not have any impact the front slow rates. The detector remains in the same condition with the slow front threshold at 0xC3.
2015-239-17:55:53 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
2015-239-17:56:02 /IDPLOAD VALUE=0x90  ; was 0x80

2015-239-17:56:56 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
2015-239-17:57:05 /IDPLOAD VALUE=0xA0  ; was 0x90

2015-239-19:34:23 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
2015-239-19:34:32 /IDPLOAD VALUE=0xC0  ; was 0xA0

2015-239-19:37:01 /IDPUTABLE4 OFFSET=FRONTFASTDAC
2015-239-19:37:09 /IDPLOAD VALUE=0xF0  ; was 0xE0

2015-239-19:39:38 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
2015-239-19:39:47 /IDPLOAD VALUE=0xC3  ; was 0xC0

2015-239-21:14:24 /ihvdac detector=4, voltage=226
2015-239-21:15:53 /ihvdac detector=4, voltage=221
  • The front fast threshold was changed on Sep 9 2015 due to low livetime. HV was lowered.
2015-252-17:50:20 /IDPUTABLE4 OFFSET=FRONTFASTDAC
2015-252-17:50:35 /IDPLOAD VALUE=0xFF  ; was 0xF0
2015-252-17:49:33 /IHVDAC DETECTOR=4, VOLTAGE=200 (3898 V)
  • On September 14 2015, HV was lowered again, with no long term effect.
2015-257-17:36:45 /IHVDAC DETECTOR=4, voltage=185 (3602 V, was 3897 V)
  • Sept. 23 2015: Despite our best efforts, there's been no success in recovering livetime from D4. The front segment livetime is essentially 0. Since desperate times call for desperate measures, we're lowering the HV by 1000V to try and recover some performance. (This was temporarily tried last week, for an orbit, and the livetime did rise to 30%.) The detector does not seem to be anywhere near segmenting. UPDATE Sept. 24: this drop was successful in bringing the fast rates down some, from 4x10^5 to 10^5. This freed up some livetime, which is now at ~35%. However, it also allowed the slow rates to skyrocket, to about 3000. This is probably cutting into the SSR, and so now the SSR fill is gradually rising (13% min today vs ~4% min yesterday). Action MAY need to be taken to reduce the fill rate.
2015-266-19:25:51 /IHVDAC DETECTOR=4, VOLTAGE=134 (2598 V)


  • 5th October 2015: G4 was primarily responsible was the increasing SSR fill level (max ~68%). Over the weekend the behavior of D4 changed causing very high fast valids and live time at or near 0%. This low live time has prevented G4 from putting a lot of noise into the SSR. However over the previous few days, the fast valids declined and the livetime rose to around 74%. This has allowed G4 to begin putting more than 9k events per second. Because of this, we further increased the G4 front slow valid, in steps up to max threshold 0xFF. This had no effect whatsoever (slow valid counts appear to be stuck on just one value). This is similar to some of the strange behavior was previously saw in G9.
15-279-00:37:28 start idib_chg_thrshld (4, FRONT, SLOW, 0xE0)  ; was 0xD0
15-279-00:37:32 /IDPUDUMPTABL TABLE=DIBTBL4
15-279-00:37:32 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
15-279-00:37:42 /IDPLOAD VALUE=0xE0

15-279-00:38:20 start idib_chg_thrshld (4, FRONT, SLOW, 0xF0)  ; was 0xE0
15-279-00:38:24 /IDPUDUMPTABL TABLE=DIBTBL4
15-279-00:38:24 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
15-279-00:38:29 /IDPLOAD VALUE=0xF0

15-279-00:39:19 start idib_chg_thrshld (4, FRONT, SLOW, 0xFF)  ; was 0xF0
15-279-00:39:23 /IDPUDUMPTABL TABLE=DIBTBL4
15-279-00:39:23 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
15-279-00:39:30 /IDPLOAD VALUE=0xFF

In order to deal with the high SSR fill level we halted collection of detector 4 events. We also loaded a modified version of RTS 26 so that G4 events would stay off, when the other detector events were turned back on, after each eclipse exit. We noted an immediate decrease in the SSR write rate, as soon as G4 events were turned off. This SSR fill level has since begun to decrease.

Turn off G4 events
15-279-02:16:10 /itmoff value=dib4

Load modified RTS 26 so the G4 events stay off 

15-279-02:17:05 start sc_tbl_loadpkt("T15271SLTN61_No_G4_G9.00")
  • 2015 December 10: lowered HV down to 1000 V. Before GRIPS launch, we wanted to test what happens if we turned D4 events back on. HV was lowered to prepare for the testing.
2015-344-21:37:30 /ihvdac detector=4, voltage=53 ; was ~1519V
  • 2015 December 12: D4 events turned on temporarily
from 346-00:32:44 to 346-00:36:16 UTC (day 346 = December 12).
  • 2016 January 8: A experiment was performed consisting in lowering the voltage of the detector from 500V to 200V, start taking events, then stop taking events and ramp back the HV to 500V.
2016-008-01:31:37 /IHVDAC DETECTOR=4, VOLTAGE=10 ; 200 V
2016-008-01:32:07 /ITMON VALUE=AFE3 ; turn on G4 events

2016-008-01:35:37 /ITMOFF VALUE=DIB4 ; turn off G4 events
2016-008-01:35:46 /IHVDAC DETECTOR=4, VOLTAGE=28 ; return to 500 V
  • 2016 January 13: A experiment was performed consisting in lowering the voltage of the detector from 500V to 200V, start taking events
2016-013-21:21:18 /IHVDAC DETECTOR=4, VOLTAGE=11 ; 200 V
2016-013-21:21:41 G4 events on
2016-013-21:24:39 G4 events off

2016-013-23:00:55 G4 events on
2016-013-23:08:06 G4 events off
  • On January 27 the slow front the threshold was changed to A0 to evaluate the impact of such change on the SSR fill level. The threshold change was made for the duration of the pass, returning to the original value of C0. The result of this experiment demonstrated a minimal impact on the SSR fill level.
2016-027-20:13:52 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
2016-027-20:14:00 /IDPLOAD VALUE=0xA0  ; was 0xC0

2016-027-20:19:10 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
2016-027-20:19:18 /IDPLOAD VALUE=0xC0  ; was 0xA0
  • On January 29, we changed the detector slow front threshold to A0 for one orbit and egain evaluated the impact of this change on the SSR fill level. Again the impact was minimal. At the end of the orbit the slow front threshold was changed to C0.
2016-029-17:44:48 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
2016-029-17:45:10 /IDPLOAD VALUE=0xA0  ; was 0xC0

16-029-19:26:50 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
16-029-19:27:07 /IDPLOAD VALUE=0xC0  ; was 0xA0

At 22:43:12 UT on January 29 the slow front threshold was changed to A0. Since then no detrimental repercussions on the SSR fill level have been observed. 

16-029-22:43:12 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
16-029-22:43:22 /IDPLOAD VALUE=0xA0  ; was 0xC0

Post 2016 Anneal

  • 2016 April 27 (DOY 118): Started turning on D4. HV reached 3995 V by April 29, ~03:40
16-119-00:49:49 start ihv_ramp_stage1_g1_g4_g7 (HV = 0x0A, ~200 V)
16-119-02:27:48 start ihv_ramp_stage2_g1_g4_g7 (HV = 0x33, 980 V)
16-119-04:08:00 start ihv_ramp_stage3_g1_g4_g7 (HV = 0x67, 1985 V)
16-120-00:22:16 start ihv_ramp_stage4_g1_g4_g7 (HV = 0x9A, ~3000 V)
16-120-02:01:36 start ihv_ramp_stage5_g1_g4_g7 (HV = 0xB3, ~3500 V)
16-120-03:41:12 start ihv_ramp_stage6_g1_g4_g7 (HV = 0xCE, 3995 V)
  • 2016 April 29, Front fast and front-slow thresholds were raised to 0x38 and 0x30, respectively.
16-120-00:28:14 /IDPUTABLE4 OFFSET=FRONTFASTDAC
16-120-00:28:25 /IDPLOAD VALUE=0x30

16-120-22:21:52  /IDPUTABLE4 OFFSET=FRONTFASTDAC
16-120-22:22:19  /IDPLOAD VALUE=0x40  ; was 0x30

16-120-23:58:19 /IDPUTABLE4 OFFSET=FRONTFASTDAC
16-120-23:58:36 /IDPLOAD VALUE=0x38

16-120-03:45:16 /IDPUTABLE4 OFFSET=FRONTSLOWDAC
16-120-03:45:31 /IDPLOAD VALUE=0x30
  • May 18, 2016 This detector turned off
2016-139-18:52:03 /ihvdac detector=4, voltage=0
2016-139-18:56:31 /idibpwroff value=4

D4 front slow LLD threshold history

post 2014 anneal 0x50
2015 May 21 19:24 UTC 0x70 (was 0x60)
2015 Aug 13 16:45 UTC 0x80 (was 0x70)
2015 Aug 27 17:56:02 UTC 0x90 (was 0x80)
2015 Aug 27 17:57:05 UTC 0xA0 (was 0x90)
2015 Aug 27 19:34:32 UTC 0xC0 (was 0xA0)
2015 Aug 27 19:39:47 UTC 0xC3 (was 0xC0)
2015 Sep 17 06:35:40 UTC 0xD0 (was 0xC3)
2015 Oct 05 00:37:28 UTC 0xE0 (was 0xD0)
2015 Oct 05 00:38:20 UTC 0xF0 (was 0xE0)
2015 Oct 05 00:39:19 UTC 0xFF (was 0xF0)
2016 Jan 27 20:14:00 UTC 0xA0 (was 0xC0)
2016 Jan 27 20:19:18 UTC 0xC0 (was 0xA0)
2016 Jan 29 17:45:10 UTC 0xA0 (was 0xC0)
2016 Jan 29 19:27:07 UTC 0xC0 (was 0xA0)
2016 Jan 29 22:43:22 UTC 0xA0 (was 0xC0)
post 2016 anneal 0x30


D4 front fast LLD threshold history

post 2014 anneal 0x30
2014-Dec-8 after 22:05 UTC 0x50 (was 0x30)
2015-Jun-02 17:00:31 UTC 0x60 (was 0x50)
2015-Jul-07 18:48:34 UTC 0x70 (was 0x60)
2015-Jul-07 19:21:25 UTC 0x80 (was 0x70)
2015-Jul-24 17:22:30 UTC 0x90 (was 0x80)
2015-Aug-20 22:18:25 UTC 0xA0 (was 0x90)
2015-Aug-20 22:19:32 UTC 0xB0 (was 0xA0)
2015-Aug-24 20:44:22 UTC 0xD0 (was 0xB0)
2015-Aug-25 00:02:22 UTC 0xE0 (was 0xD0)
2015-Aug-27 19:37:09 UTC 0xF0 (was 0xE0)
2015-Sep-09 17:50:35 UTC 0xFF (was 0xF0)
post 2016 anneal 0x38


D4 rear slow LLD threshold history

post 2014 anneal 0x30

D4 rear fast LLD threshold history

post 2014 anneal 0x45
2015-Sep-17 06:37:27UTC 0x55 (was 0x45)

D4 HV history

post 2014 anneal 4510 V
2015-Aug-27 21:15:53 UTC 4289 V (was 4510 V)
2015-Sep-09 17:49:33 UTC 3898 V (was 4289 V)
2015-Sep-14 17:36:45 UTC 3602 V (was 3897 V)
2015-Sep-23 19:25:51 UTC 2598 V (was 3602 V)
2015-Dec-10 21:37:30 UTC 1000 V (was 1519 V)
2015-12-17 18:47:12 UTC 500 V (was 1000 V)
2016-01-08 01:31:37 UTC 200 V (was 500 V)
2016-01-08 01:35:37 UTC 500 V (was 200 V)
2016-01-13 21:21:18 UTC 200 V (was 500 V)
post 2016 anneal 3995 V
2016-05-18 18:56:31 0V
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