Detector 4 anneal 2012

From RHESSI Wiki

• Detector 4 was unsegmented after the 2012 anneal. The entire detector volume is read out through the front segment electronics, so rates look higher for G4 (and also G2) than for the other detectors. (UPDATE: segmentation occurred spontaneously in late 2012; see later entries.)

• 6 November 2012: The front fast and slow thresholds on detector 4 were optimized during 2 passes. The front slow threshold was reduced significantly, down to the nominal value used by segmented detectors, without seeing a large increase in noise. The front fast threshold was lowered a little as well, but not by nearly as much.

G4 Front Slow 0x70 to 0x0C.

G4 Front Fast 0x60 to 0x50.

• 2012-dec-12: D4 has been spontaneously segmenting and desegmenting for approximately the past 30 days, it began on day 317. The high voltage was raised by 5 steps to stabilize the segmentation, and it appears to be initially successful. Brian Dennis made some plots to show that its resolution is as good as before the anneal. He also showed that the calibration used in SSW is not up to date.

• 2012 December 19: D4 was still desegmenting during and after the SAA, so the voltage was raised by 5 steps again on Dec. 17 (DOY 352) to 4215.7 V.

• 2012 December 26: The voltage was raised again on Dec. 21 to 4313.8V. D4 is now segmenting consistently, except for a very brief interval during the SAA.

• 2013 November 9: There were some isolated spikes. No further spiking occurred in the remainder of the week. See: http://sprg.ssl.berkeley.edu/~tohban/browser/?show=grth1+qlpcr+qlpfr+qlprr+monfs+monrs&date=20131109&time=051222