Post 2016 Anneal Detector Operations

After the 2016 anneal, thermal considerations have led to the necessity of operating a subset of detectors at a time. This page describes the different modes for normal operations, times of high solar activity and campaigns. The document ends with a discussion of the different inputs and considerations in determining these modes.

• This information and campaign modes are largely copied from a document generated by Gordon and Sa"m (distributed to the Tohban list) and discussion during the 2016 May 18 and 2016 May 25 RHESSI operations meetings.

Normal Operation

For thermal considerations, two detectors will be turned on and operated for normal data collection. At this time, D3 and D8, are the best candidates for general microflare studies.

• Good locations from D8;
• Possible footpoint locations from D3.
• Possible “D6- equivalent” low sensitivity imaging data from D8.

Status

• 2016 May 18: D3 and D8 have high voltage turned up and are ready for data collection

Extremely Low Solar Activity

The thermal input from detectors and their electronics contribute significant heat input into the cryostat. It was suggested that under extremely quiet sun conditions we turn off all detectors for a short time so that we can drive down the cryocooler temperature. This option requires much further discussion and has not been agreed upon.

High Solar Activity

When the Sun is active and the forecast calls for heightened activity a third detector will be turned on for monitoring. At this time D1 and D9 are the best candidates for general monitoring.

• Spectroscopy contribution from D1
• Good locations from D9

Large Flare Observations

When the flare forecast calls for a Great Flare watch, enable more than 3 detectors for a short duration

• Use D1 through D9 (or a thermally-limited subset):
• D1, D2, D4, D5, D6, D7 could provide non-thermal imaging data
• D3, D8, D9 and D8, D9 3rd harmonics could provide both thermal & nonthermal imaging data

Inputs and Assumptions

• D1, D3, D8, D9 are viable segmented detectors.
• D2, D4, D5, D6, D7 are viable unsegmented detectors – usable only at ‘nonthermal’ energies.
• Acceptable thermal stability with 2 (TBC) detectors turned on.
• Powering additional detectors slowly raises temperature.
• D7, D8, D9 may provide useful 3rd harmonic response at all azimuths (down by x9 sensitivity) but no useful 2nd harmonic response.
• D3 to D6 3rd harmonic response is limited to selected azimuths.
• D3 to D6 2nd harmonic response is limited to other selected azimuths. (and down by x4 in sensitivity)
• D9 spectroscopy normalization compromised by slow modulation.
• D1 is primarily useful for spectroscopy since in most cases, sources are sufficiently large that D1 maps are not so useful. This will be especially the case if there is a lack of coarser resolution mapping data.
• Very little software development needed to support harmonic imaging

To do

• Confirmation / evaluation of imaging effectiveness of 2nd & 3rd harmonic.
• Working guidelines (parameterized model) for estimating temperature rise (rate and equilibrium) for each extra powered detector.
• Develop ‘turnkey’ scripts for turning detectors ON / OFF.
• User-expectation guidelines for exploiting limited detector & harmonic imaging.
• Review of imaging algorithms to evaluate suitability for imaging with limited detectors and harmonic