Tohban Report 2015-09-30

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(Spacecraft Management)
(Detector issues)
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== Detector issues ==
== Detector issues ==
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* On Sept 23, it was decided that the last changes to the slow threshold were probably too drastic, especially considering that the fast threshold was changed at the same time.  We backed the front slow threshold back down to 0x1C, which is what it had been before the last adjustment.  This needs to be monitored to see how D3 operates in this state, and keep an eye on the slow rates + SSR.
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* On Sept 23, it was decided that the last changes to the slow threshold were probably too drastic, especially considering that the fast threshold was changed at the same time.  We backed the front slow threshold back down to 0x1C, which is what it had been before the last adjustment.  This needs to be monitored to see how D3 operates in this state, and keep an eye on the slow rates + SSR.  UPDATE Sept. 24: the D3 event rate did not significantly change with this threshold drop.  Livetime is still ~90% (same as before the drop) so I think this is a stable, working condition.  If more livetime is desired, the fast threshold could be raised again.
  2015-266-19:24:00 /IDPUTABLE3 OFFSET=FRONTSLOWDAC
  2015-266-19:24:00 /IDPUTABLE3 OFFSET=FRONTSLOWDAC
  2015-266-19:24:12 /IDPLOAD VALUE=0x1C  ;was 0x80
  2015-266-19:24:12 /IDPLOAD VALUE=0x1C  ;was 0x80
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* 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.
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* 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 should be taken to reduce the fill rate.
  2015-266-19:25:51 /IHVDAC DETECTOR=4, VOLTAGE=134 (2598 V)
  2015-266-19:25:51 /IHVDAC DETECTOR=4, VOLTAGE=134 (2598 V)
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== Other notes ==
== Other notes ==

Revision as of 17:56, 27 September 2015


Tohban Reports
Start Date: 23 Sep 2015
End Date: 30 Sep 2015
Tohban: Lindsay Glesener
Tohban email: glesener@ssl.berkeley.edu
Next Tohban: TBD
List all reports



Contents

Solar Activity

Memory Management

Spacecraft Status

Data Gaps

Detector issues

2015-266-19:24:00 /IDPUTABLE3 OFFSET=FRONTSLOWDAC
2015-266-19:24:12 /IDPLOAD VALUE=0x1C   ;was 0x80
2015-266-19:25:51 /IHVDAC DETECTOR=4, VOLTAGE=134 (2598 V)

Other notes

Spacecraft Management

Decimation Active/Vigorous
HLAT Decimation Rear decimation weight 6, no front decimation
Night time data (fronts) +/- 4 minutes
Night time data (rears) +/- 4 minutes
Require extra passes? No
Requirement for moving pointer? No
Attenuator operation See Above
Detector problems? See notes above.
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