Tohban Report 2015-07-15
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Front status notes: | Front status notes: | ||
| - | * D6 has very high resets and high event rates. This could be one of the causes of the high SSR fill. | + | * D6 has very high resets (essentially flatlined with no more orbital variation) and high event rates. This could be one of the causes of the high SSR fill. But HV is low (<2kV) so maybe dangerous to drop more. This behavior has been consistent for weeks. Investigation of whether D6 is returning good data would be useful. |
| + | * D4 and D6 have high slow rates. | ||
| + | * D8 and D9 have very low livetimes. (~80% for D8 and <50% for D9). These have been steadily dropping since about June 24. Before that, there were some slow drops and slow rises. Changes are very gradual, with no large jumps. (Plots of this would be useful.) Both detector fast thresholds were raised on June 11, with only a tiny effect on the livetime. Interesting note: D9’s fast rates dropped dramatically at this change, but D8’s did NOT. Neither detector increased much in LT. This situation persists to this day — D8’s fast rates are quite high. D9 has low slows, fasts, and resets. | ||
| + | * D4's LT is still a little low (90-95%), though the last fast threshold raise helped.. Could raise fast threshold even more. | ||
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== Attenuators == | == Attenuators == | ||
Revision as of 18:15, 12 July 2015
| Tohban Reports | |
|---|---|
| Start Date: | 01 Jul 2015 |
| End Date: | 08 Jul 2015 |
| Tohban: | Lindsay Glesener |
| Tohban email: | glesener@ssl.berkeley.edu |
| Next Tohban: | TBD |
| List all reports | |
Contents |
Solar Activity
Memory Management
The SSR is still not emptying. Source of large fill is unclear.
Temperatures
Spacecraft Status
Data Gaps
Detector Issues
Detector 3 and 4 had low front livetimes, so the front fast thresholds were changed on both of these detectors on July 9:
2015-191-19:20:47 /IDPUTABLE3 OFFSET=FRONTFASTDAC 2015-191-19:20:58 /IDPLOAD VALUE=0x40 ; was 0x30
2015-191-19:21:17 /IDPUTABLE4 OFFSET=FRONTFASTDAC 2015-191-19:21:25 /IDPLOAD VALUE=0x80 ; was 0x70
This action was effective in decreasing fast rates and increasing livetime in both detectors. Afterward, D3 and D4 front livetimes were typicaly XXXX.
Front status notes:
- D6 has very high resets (essentially flatlined with no more orbital variation) and high event rates. This could be one of the causes of the high SSR fill. But HV is low (<2kV) so maybe dangerous to drop more. This behavior has been consistent for weeks. Investigation of whether D6 is returning good data would be useful.
- D4 and D6 have high slow rates.
- D8 and D9 have very low livetimes. (~80% for D8 and <50% for D9). These have been steadily dropping since about June 24. Before that, there were some slow drops and slow rises. Changes are very gradual, with no large jumps. (Plots of this would be useful.) Both detector fast thresholds were raised on June 11, with only a tiny effect on the livetime. Interesting note: D9’s fast rates dropped dramatically at this change, but D8’s did NOT. Neither detector increased much in LT. This situation persists to this day — D8’s fast rates are quite high. D9 has low slows, fasts, and resets.
- D4's LT is still a little low (90-95%), though the last fast threshold raise helped.. Could raise fast threshold even more.
Attenuators
In the last tohban week, we performed an experiment where we had changed the deadtime threshold for shutter insertion from the nominal 5.1% to 10%. This was intended to get better low-energy data for Brian and others to do low-energy HXR investigations. However, we found that with that new deadtime threshold, the shutter inserted not that much later (i.e. when the flare gets bright, it gets really bright, and so you'd have to change the threshold by a LOT to make a difference). Also, in some of the shutter-out intervals the pileup effect was quite high. It didn't seem productive to continue this experiment, so the deadtime threshold was returned to the nominal 5.1%. It was discussed at last week's meeting that at some point in the future we may disable the shutter altogether in order to get Brian his low-energy data for an entire flare, but we will not try this yet.
The return to nominal deadtime threshold for shutter insertion was done on 2015-189-20:05:38 UTC (July 8, 2015).
On July 9 at ~03:25 UTC, the thin attenuator went in and stayed until Jeremy noticed it and commanded it out. On investigation, it was determined that dead time on 1 and 7 had risen to a level which wouldn't allow the thin shutter to come out. (Typical livetime was 98.5%, which is less than the deinsertion threshold of 98.8%.) No individual problems were found in either D1 or D7 (no high fast or slow rates or resets). Furthermore, D1 and D7 LT were tracking each other well, so it was not an individual detector problem. It was therefore decided to change the attenuator deinsertion dead time threshold to 1.96% deadtime (98.04% livetime).
The deinsertion deadtime threshold change was done on July 10. Jeremy's summary: "The attenuator threshold value was changed to "5" at 2015-191-19:22:12 (Friday July 10, 2015). The Thin attenuator should now come out when the average live time of G1 and G7 is above 98.04%"
Spacecraft Management
| Decimation | Normal/Vigorous |
| Night time data (fronts) | No night events |
| Night time data (rears) | No night events |
| Require extra passes? | No |
| Attenuator operation | Sometimes stuck in A1; see notes above. |
