Detector 6

This page contains information about changes/issues for RHESSI detector 6 after the 2014 anneal. Detector updates from 2012-mid 2014 can be found here: Detector 6 anneal 2012

Notes

After the 2014 anneal, detector 6 began its reincarnated life as an unsegmented detector but segmented shortly after (see below).

• On 2014 August 14, the HV on D6 was raised to 4926V in an attempt to segment it. This was successful, and D6 now operates as a segmented detector. Since its segmentation is borderline as of Aug/Sept 2014, it commonly unsegments during and just after the SAA.

• On 2014 Jan 8, the rear fast threshold was raised since fast counts were eating up a lot of livetime.

 15-008-17:44:55 /IDPUTABLE6 OFFSET=REARFASTDAC
 15-008-17:45:18 /IDPULOAD VALUE=0x50           ;(was 0x45)

• * D6 has been showing some strange peaks in the spectrum; these are best seen as multiple lines (that drift) in spectrograms. On Monday, Jan 28 we raised the slow front threshold on D6 to ~10 keV and kept it there for a day before returning to the nominal ~3 keV. This is intended to see if the slow threshold affects the abnormal spectral lines.

 15-026-21:57:13 / D6 front slow threshold to 0x30 (was 0x0C).
 15-027-21:37:03 / D6 front slow threshold to 0x0C (was 0x30).

• D6 fast rates are a bit high (have been rising slowly over the past week). It would be a good idea to raise the front fast threshold a touch. I didn't want to do this at the same time as the slow threshold experiment!

• D6 front fast threshold was adjusted from default (0x22) due to increased rates, based on the above suggestion. Rates dropped from 3300 to 1250 when the change was made.

 15-030-00:19:54 /IDPUTABLE6 OFFSET=FRONTFASTDAC
 15-030-00:20:17 /IDPLOAD VALUE=0x30   ; was 0x22

• On 2015 February 27 Front Fast threshold was raised

15-058-21:41:11 /IDPUTABLE6 OFFSET=FRONTFASTDAC
15-058-21:41:44 /IDPLOAD VALUE=0x40 (was 0x30)

• Another raise to D6 front fast threshold on 2015 March 9:

 15-068-01:26:56 /IDPUTABLE6 OFFSET=FRONTFASTDAC
 15-068-01:27:07 /IDPLOAD VALUE=0x50

• On 2015 March 13 another raise was made to D6 front fast threshold and a raise of the rear fast threshold was made:

 15-072-22:04:01 /IDPUTABLE6 OFFSET=FRONTFASTDAC
 15-072-22:04:22 /IDPLOAD VALUE=0x60
 
 15-072-22:05:07 /IDPUTABLE6 OFFSET=REARFASTDAC
 15-072-22:05:17 /IDPLOAD VALUE=0x60

• Again 2015 March 17 D6 front fast threshold was increased:

 15-076-20:44:01 /IDPUTABLE6 OFFSET=FRONTFASTDAC
 15-076-20:44:14 /IDPLOAD VALUE=0x70

On 2015 March 20 D6 HV was dropped in two 10 step increments, twice. Also we attempted to lower the front fast threshold to 0x50, but changed this almost immediately when the live time dropped to 3%:

 15-079-21:10:49 /IHVDAC DETECTOR=6, VOLTAGE=243
 15-079-21:12:47 /IHVDAC DETECTOR=6, VOLTAGE=233

 15-079-22:49:23 /ihvdac detector=6, voltage=223
 15-079-22:50:44 /ihvdac detector=6, voltage=213

 15-079-22:52:39 /IDPUTABLE6 OFFSET=FRONTFASTDAC
 15-079-22:52:58 /IDPLOAD VALUE=0x60

 15-079-22:55:07 /IDPUTABLE6 OFFSET=FRONTFASTDAC
 15-079-22:55:19 /IDPLOAD VALUE=0x50

 15-079-22:55:53 /IDPUTABLE6 OFFSET=FRONTFASTDAC
 15-079-22:56:01 /IDPLOAD VALUE=0x70

On 2015 March 25 D6 HV was dropped in 20 steps.

15-084-22:45:15 /ihvdac detector=6, voltage=203
15-084-22:46:45 /ihvdac detector=6, voltage=193 (3750 V)

• April 7 2015: the front fast threshold was raised due to high fast rates that were significantly reducing livetime. This helped, but not a lot, so the action will probably be repeated soon.

15-097-19:56:35 /IDPUTABLE6 OFFSET=FRONTFASTDAC
15-097-19:56:45 /IDPLOAD VALUE=0x80 ; was 0x70

• April 9 2015: The front fast and the front slow threshold were raised up to recover the livetime and trying to reduce the noise on the slow valid counts.

15-099-17:32:59 /IDPUTABLE6 OFFSET=FRONTFASTDAC
15-099-17:33:11 /IDPLOAD VALUE=0xA0

15-099-21:17:16 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
15-099-21:17:27 /IDPLOAD VALUE=0x15

• On April 14 starting at 14:06 UT we made the next changes for detectors 6 trying to decrease valid counts on the Slow Front segment.

15-104-14:11:57 /IDPUTABLE6 OFFSET=FRONTFASTDAC
15-104-14:12:05 /IDPLOAD VALUE=0xA8
15-104-15:45:14 /IDPLOAD VALUE=0xB0
15-104-15:46:24 /IDPLOAD VALUE=0xB8
15-104-15:47:36 /IDPLOAD VALUE=0xB0

15-104-15:49:18 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
15-104-15:49:25 /IDPLOAD VALUE=0x1A
15-104-15:50:30 /IDPLOAD VALUE=0x1F
15-104-15:52:06 /IDPLOAD VALUE=0x15

• On May 21 starting at 19:23 UTC we made the next changes on Front Slow threshold:

15-141-19:25:36 start idib_chg_thrshld (6, FRONT, SLOW, 0x20)  --> Was 0x15
15-141-19:25:46 /IDPUDUMPTABL TABLE=DIBTBL6
15-141-19:25:47 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
15-141-19:25:55 /IDPLOAD VALUE=0x20

• On May 26 we lowered the HV on detector 6 by 30 counts to a value of 1984 V. This change gave detector 6 the lowest voltage of all the detectors. G6 remained segmented through the pass.

2015-146-19:11:11 /IHVDAC DETECTOR=6, VOLTAGE=103 (1985 V)

We also increased the rear fast threshold on detector 6 by 0x08

2015-146-19:13:07 /IDPUTABLE6 OFFSET=REARFASTDAC
2015-146-19:13:25 /IDPLOAD VALUE=0x68 ; was 0x60

• On 2015 July 7, D6 rear fast threshold was raised due to decreased livetime

2015-188-18:49:02 /IDPUTABLE6 OFFSET=REARFASTDAC
2015-188-18:49:19 /IDPLOAD VALUE=0x70  ; was 0x68

• The rear fast threshold was changed on July 13 2015 due to dropping livetime in the rear:

2015-194-16:34:40 /IDPUTABLE6 OFFSET=REARFASTDAC
2015-194-16:34:52 /IDPLOAD VALUE=0x80 ; was 0x70

• The rear fast threshold was changed on July 24 2015 due to low livetime. However, the change probably wasn't needed; the tohban hadn't noticed that a change had already been made a few days ago. The next tohban can reverse the change if desired.

2015-205-17:19:29 /IDPUTABLE6 OFFSET=REARFASTDAC
2015-205-17:19:45 /IDPLOAD VALUE=0xB0 ; was 0xA0

• Aug. 24, 2015: Detector 6: Both front and rear fast thresholds were raised again. This successfully brought the livetime up to 75% in the front, but didn't really change anything in the rear. Another attempt was made with the rear fast threshold, but again no change. The slow threshold was also raised, which brought the slow rates down from 200k to 5k.

2015-236-20:44:59 /IDPUTABLE6 OFFSET=FRONTFASTDAC
2015-236-20:45:10 /IDPLOAD VALUE=0xD0  ; was 0xB0

2015-237-00:02:53 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
2015-237-00:03:04 /IDPLOAD VALUE=0x25 ;  was 0x20

2015-236-20:47:27 /IDPUTABLE6 OFFSET=REARFASTDAC
2015-236-20:47:36 /IDPLOAD VALUE=0xC0 ; was 0xB0

2015-237-00:04:26 /IDPUTABLE6 OFFSET=REARFASTDAC
2015-237-00:04:34 /IDPLOAD VALUE=0xD0 ; was 0xC0

• Detector 6 was showing elevated slow front rates. We made a HV change on August 28, lowering the voltage by 200V. The change made the slow front rates to decrease, but still the detector shows elevated slow front counts. On August 31, the rear fast threshold was raised to increase the detector livetime.

2015-240-17:32:26 /ihvdac detector=6, voltage=93 (from 1984 to 1789 V)

2015-243-18:01:47 /IDPUTABLE6 OFFSET=REARFASTDAC
2015-243-18:01:56 /IDPLOAD VALUE=0xE0 ; was 0xD0 

• The rear fast threshold was changed on Sep 9 2015 due to low livetime.

2015-252-17:53:05 /IDPUTABLE6 OFFSET=REARFASTDAC
2015-252-17:53:18 /IDPLOAD VALUE=0xF0 ; was 0xF0

• On September 14 2015 we raised the rear fast threshold on D6 from 0xF0 to 0xFF and on September 15 we raised the RHESSI D6 front slow threshold from 0x25 to 0x30.

2015-257-17:35:39 /IDPUTABLE6 OFFSET=REARFASTDAC
2015-257-17:35:49 /IDPLOAD VALUE=0xFF ; was 0xF0

2015-258-17:09:29 /IDPUTABLE6 OFFSET=frontslowDAC
2015-258-17:09:38 /IDPLOAD VALUE=0x30 ; was 0x25

• 2nd October 2015: We increased the front slow thresholds, on detectors G3 and G6.

15-278-21:29:49 start idib_chg_thrshld(6, FRONT, SLOW, 0x40)  ; was 0x30
15-278-21:29:53 /IDPUDUMPTABL TABLE=DIBTBL6
15-278-21:29:53 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
15-278-21:30:03 /IDPLOAD VALUE=0x40

• 5th October 2015: We increased the front slow thresholds G6

15-279-00:40:54 start idib_chg_thrshld (6, FRONT, SLOW, 0x50)  ; was 0x40
15-279-00:40:58 /IDPUDUMPTABL TABLE=DIBTBL6
15-279-00:40:58 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
15-279-00:41:08 /IDPLOAD VALUE=0x50

• On October 8, the front fast threshold was raised to try and raise livetime. Prior to these changes, D6 front livetime was at ~20%. As the changes were made on a BGS pass, the D6 front fast rates fell from 100k to 9000, and the front LT rose to 78%, but then worsened a lot the next day, so more action was taken (see next item).

2015-281-21:49:49 /IDPUTABLE6 OFFSET=FRONTFASTDAC
2015-281-21:49:59 /IDPLOAD VALUE=0xFF  ; was 0xE0

• On October 12, the HV on detector 6 was dropped by 200V, to ~1600V. The reasons for this: D6 front livetime had plummeted, and the fast threshold was already maxed. I considered raising the slow threshold but concluded that this is unlikely to help the problem -- the previous two slow threshold raises did no good at all, spectrograms have shown that the event noise is across the energy spectrum, not exclusively at low energies, and right now it's clearly the high fast rates that are eating up all the livetime, not the slows. So something is necessary to reduce fast rates, and an HV drop is the only shot at that. This also may help some of the other issues with D6. A first look at the results indicates that this change was successful in reducing fast rates and raising livetime. Hooray! Livetime is at ~80% after the voltage drop. Continue to watch this detector.

2015-285-21:52:42 /IHVDAC DETECTOR=6, VOLTAGE=83  ;1593 V (was 1789 V)

• On October 28 in an attempt to lower the high reset rates and the front slow counts registered the HV on the detector was changed to ~1397.

 2015-301-20:28:46 /ihvdac detector=6, voltage=73

• November 11, front slow threshold lowered from 0x50 to 0x40. The noise appears

relatively flat at those values, and we shouldn't experience too much additional noise counts.

2015-318-07:03:56 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
2015-318-07:04:07 /IDPLOAD VALUE=0x40  ; was 0x50

• 2015 December 10 & 12, front slow threshold lowered in an attempt to recover energy spectrum before GRIPS.

2015-344-19:58:19 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
2015-344-19:58:28 /IDPLOAD VALUE=0x30 ; was 0x40

2015-346-00:33:12 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
2015-346-00:33:22 /IDPLOAD VALUE=0x20  ; was 0x30

• 2016 January 8: The slow front threshold was increased from 0x30 to 0x80.

2016-008-01:32:23 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
2016-008-01:32:32 /IDPLOAD VALUE=0x80  ; was 0x30

• 2016 January 13, 15: We dropped the D6 HV to 500 V, to reduce noise and see if any spectrum could be recovered. No luck there, so on 15 january, we dropped the HV to 200 V. D6 desegmented and began to fill the memory. We raised the HV back to 500 V, and turned events off.

2016-013-23:02:09 /ihvdac detector=6, voltage=28 ; 500 V

2016-015-01:41:44 /ihvdac detector=6, voltage=11
2016-015-23:40:07 /ITMOFF VALUE=DIB6 ; off permanently
2016-015-23:40:25 /IHVDAC DETECTOR=6, VOLTAGE=28 ; 500 V

Post 2016 anneal

• This detector was turned on on 26 January 2017

• On 9-Feb-2017, the front fast threshold was raised from 0x70 to 0x80

2017-039-20:11:12 /IDPUTABLE6 OFFSET=FRONTFASTDAC 2017-039-20:11:21 /IDPULOAD VALUE=0x80 ; was 0x70

• On 21-Feb-2017, front fast threshold was raised from 0x80 to 0x90

17-052-17:21:46 start idib_chg_thrshld(6,FRONT,FAST,0x90) ; was 0x80
17-052-17:22:22 start show_temps_avg
17-052-17:22:40 CP1: 152.6 K
17-052-17:22:40 CP2: 151.2 K
17-052-17:22:40 CT1: 127.9 K
17-052-17:22:40 CT2: 126.1 K
17-052-17:22:40 TST: 189.0 K
17-052-17:22:40 cp1 - ct1 = 24.61 K
17-052-17:22:40 Cryo Power: 75.4 W
17-052-17:22:40 Cryo Accel: 12.1 mG

• On May 15 at 17:50 we lowered the HV from ~3400V to ~2000 V as an experiment to increase the Livetime. The experiment worked well.

2017-135-17:50:10 /ihvdac detector=6, voltage=103 ; 2000 V

• 16 August 2017, raised front slow threshold to reduce low energy noise

17-228-19:57:37 start idib_chg_thrshld(6,FRONT,SLOW,0x1C)
17-228-19:57:41 /IDPUDUMPTABL TABLE=DIBTBL6
17-228-19:57:41 /IDPUTABLE6 OFFSET=FRONTSLOWDAC
17-228-19:57:48 /IDPULOAD VALUE=0x1C

• On 27-sep-2017, the front fast rate threshold for detector 6 was lowered to 0x20, in an attempt to set the threshold to such a low value that individual fast rate counts would not be distinguished, thus reducing the fast rates and increasing live time. This was not successful, and the threshold was raised back to 0xFF.

Here are the command times (UTC):

2017-270-19:33:14 /IDPUTABLE6 OFFSET=FRONTFASTDAC
2017-270-19:33:24 /IDPULOAD VALUE=0x80 ; was 0xFF

2017-270-19:34:03 /IDPUTABLE6 OFFSET=FRONTFASTDAC
2017-270-19:34:08 /IDPULOAD VALUE=0x40

2017-270-19:34:45 /IDPUTABLE6 OFFSET=FRONTFASTDAC
2017-270-19:34:50 /IDPULOAD VALUE=0x30

2017-270-19:35:30 /IDPUTABLE6 OFFSET=FRONTFASTDAC
2017-270-19:35:35 /IDPULOAD VALUE=0x20

2017-270-19:36:21 /IDPUTABLE6 OFFSET=FRONTFASTDAC
2017-270-19:36:29 /IDPULOAD VALUE=0x10

2017-270-19:37:30 /IDPUTABLE6 OFFSET=FRONTFASTDAC
2017-270-19:37:35 /IDPULOAD VALUE=0x00

2017-270-19:38:14 /IDPUTABLE6 OFFSET=FRONTFASTDAC
2017-270-19:38:18 /IDPULOAD VALUE=0xFF

• 3 November 2017: Rear fast threshold raised to 0xFF

17-307-16:32:54 start idib_chg_thrshld(6,rear,fast,0xFF) , was 0x60
17-307-16:32:58 /IDPUDUMPTABL TABLE=DIBTBL6
17-307-16:32:58 /IDPUTABLE6 OFFSET=REARFASTDAC
17-307-16:33:08 /IDPULOAD VALUE=0xFF

D6 front slow LLD threshold history

post 2014 anneal	0x0C (after segmentation)
2015 Jan 26 21:57:13 UTC	0x30 (was 0x0C)
2015 Jan 27 21:37:03 UTC	0x0C (was 0x30)
2015 Apr 09 21:17:27 UTC	0x15 (was 0x0C)
2015 Apr 14 15:49:25 UTC	0x1A (was 0x15)
2015 Apr 14 15:50:30 UTC	0x1F (was 0x1A)
2015 Apr 14 15:52:06 UTC	0x15 (was 0x1F)
2015 May 21 19:25:36 UTC	0x20 (was 0x15)
2015 Aug 25 00:03:04 UTC	0x25 (was 0x20)
2015 Sep 15 00:17:09 UTC	0x30 (was 0x25)
2015 Oct 02 21:29:49 UTC	0x40 (was 0x30)
2015 Oct 05 00:40:54 UTC	0x50 (was 0x40)
2015-11-14 07:04:07 UTC	0x40 (was 0x50)
2015-12-10 19:58:19 UTC	0x30 (was 0x40)
2015-12-12 00:33:22 UTC	0x20 (was 0x30)
2016-01-08 01:32:32 UTC	0x80 (was 0x30)
post 2016 anneal	0x68
2017-08-16 19:57:48	0x1C

D6 front fast LLD threshold history

post 2014 anneal	0x22 (after segmentation)
2015-Jan-30 00:20:17	0x30 (was 0x22)
2015-Feb-27 21:41:44	0x40 (was 0x30)
2015-Mar-09 01:27:07	0x50 (was 0x40)
2015-Mar-13 22:04:22	0x60 (was 0x50)
2015-Mar-17 20:44:14	0x70 (was 0x60)
2015-Mar-20 22:52:58	0x60 (was 0x70)
2015-Mar-20 22:55:19	0x50 (was 0x60)
2015-Mar-20 22:56:01	0x70 (was 0x50)
2015-Apr-07 19:57	0x80 (was 0x70)
2015-Apr-09 17:33	0xA0 (was 0x90)
2015-Apr-14 14:12	0xA8 (was 0xA0)
2015-Apr-14 15:45	0xB0 (was 0xA8)
2015-Apr-14 15:46	0xB8 (was 0xB0)
2015-Apr-14 15:48	0xB0 (was 0xB8)
2015-Aug-24 20:45:10	0xD0 (was 0xB0)
2015-Sep-21 19:47:33	0xE0 (was 0xD0)
2015-Oct-08 21:49:59	0xFF (was 0xE0)
post 2016 anneal	0x40
2017-Feb-08 20:11:21	0x80 (was 0x70)
2017-Feb-21 17:22:22	0x90 (was 0x80)
2017-Feb-28 20:49:32	0xB0 (was 0x90)
2017-Mar-01	0xFF

D6 rear slow LLD threshold history

post 2014 anneal	0x30 (after segmentation)
post 2016 anneal	0x30

D6 rear fast LLD threshold history

post 2014 anneal	0x45 (after segmentation)
2015-Jan-08 17:45:18	0x50 (was 0x45)
2015-Jan-08 17:45:18	0x50 (was 0x45)
2015-Mar-17 22:05:17	0x60 (was 0x50)
2015-May-26 19:13:07	0x68 (was 0x60)
2015-Jul-07 18:49:19	0x70 (was 0x68)
2015-Jul-13 16:34:52	0x80 (was 0x70)
2015-Jul-29 17:19:45	0xB0 (was 0xA0)
2015-Aug-24 20:47:36	0xC0 (was 0xB0)
2015-Aug-25 00:04:34	0xD0 (was 0xC0)
2015-Aug-31 18:01:56	0xE0 (was 0xD0)
2015-Sep-09 17:53:18	0xF0 (was 0xE0)
2015-Sep-14 17:35:49	0xFF (was 0xF0)
post 2016 anneal	0x45
2017-Jan-27	0x60
2017-Nov-03 16:32:54	0xFF (was 0x60)

D6 HV history

post 2014 anneal	4510 V (unsegmented)
2014-Aug-14 03:40 UTC	4926 V (was 4510 V) (segmented)
2015-Mar-20 21:12 UTC	4500 V (was 4926 V)
2015-Mar-20 22:50 UTC	4142 V (was 4500 V)
2015-Mar-25 22:47 UTC	3750 V (was 4142 V)
2015-May-26 19:11 UTC	1985 V (was 2573 V)
2015-Aug-28 17:32 UTC	1789 V (was 1985 V)
2015-Oct-12 21:52:42 UTC	1593 V (was 1789 V)
2015-Oct-28 20:28:46 UTC	1397 V (was 1593 V)
2016-Jan-13 23:02:09 UTC	500 V (was 1000 V)
2016-Jan-15 01:41:44 UTC	200 V (was 500 V)
2016-Jan-15 23:40:25 UTC	500 V (was 200 V)
post 2016 anneal	0V
2016-Mar-01 12:37:00 UTC	3480 V
2017-May-15 17:50:10 UTC	2000 V (was 3400 V)