Martin%20Cup

1
Experience with the software of Czech HXRS
X-ray photometer aboard the DoD satellite

• Martin Cupák
• (Martin.Cupak _at_ seznam.cz)?
• The First SphinX Workshop
• May 2007, Wroclaw, Poland

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HXRS Hard X-Ray spectrometer

• 8 Energy bands
• Basic band range 12.6-250 keV
• 2 detectors magnetically schielded and
  non-schielded
• NaI(Tl) crystal detector photomuliplier
• Data rate 256/1280 bit/s
• Key SW features
• Automatic integration time switching (1s, 0.2s)?
• Automatic band division shifting
• Optimized routine for counting X-ray photon
  events in energy bands
• Time-efficient in-flight calibration algorithm

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Automatic band division shifting
Automatic integration time switching

• 1.0s Quiet mode, data rate 256 bit/s
• 0.2s Flare mode, data rate 1280 bit/s
• Condition for integration time switching
• To 0.2s Lowest two energy bands pulses count gt
  150 / 1.0s
• To 1.0s Lowest two energy bands pulses count lt
  20 / 0.2s

• Shift to 18.8 keV (pre-callibrated HV)
• Shift to 38.3 keV (pre-callibrated HV)?
• Automatic shift (HV decreased by fixed value)
• Condition For HV schifting
• Shift ahead gt 6.000 total pulses / 0.2s
• Shift back lt 2.000 total pulses / 0.2s

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Optimized routine for counting X-ray photon
events in energy bands

• 8-bit AD converter 256 possible values, but
  only 8 energy bands
• Task be able to count pulses faster then
  instrument dead time (4us)?
• CPU with limited performance (80C166 at 20MHz)?
• Solution redundant hash table ... 312000 pulses
  per second (3.2us)?

Counts table
HashTable
CountsTable
Band
Count
0
1
2
3
INC
4
5
6
7
INC( CountsTable HashTable ADCvalue
)? example HashTable 86 3 INC(
CountsTable 3 )?
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Time-efficient in-flight calibration algorithm

• As a radiation source, Am241 (with symmetric
  peak at 59.5 keV)
• on a moving arm is used
• Algorithm balancing of two narrow symmetric
  energy bands
• The gain of the photomultiplier is defined by
  High Voltage (HV)?
• HV is controlled by DAC (12-bit, 4096 levels)?
• Linear calibration efficiency n
• Bisection method efficiency log2(n)?

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Time-efficient in-flight calibration algorithm

• Principle balancing of two symmetric energy
  bands
• The pass criteria is the channels balance and
  total number of pulses in both channels
• Start with original/default HV value and initial
  HV step
• Accumulate pulses with HVtest HV(n-1) HVstep
• If balance is better then with HV(n-1), HV
  Hvtest, go to 6
• Accumulate pulses with HV HV(n-1) HVstep
• If balance is better then with HV(n-1), HV
  HVtest
• HVstep HVstep/2
• If Hvstep lt 1, go to 2
• If current status is worse then before the
  calibration, use the HV value before the
  calibration

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HXRS Ground segment data processing SW
AI CAS Ondrejov
NASA / NOAA
Workstation
Data server
SCOS Data server
Binary files storage
HXRS Edit IDL-based Binary/FITS file
viewer/editor
Automatic conversion
NOAA Data server
Solarsoft, SPEX
FITS files storage
FITS files storage
Public access
Web Server
Web browser HXRS View (public version)?
Catalog of Selected Flare events
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• Thank you for attention