Subject: JEMX internal meeting 2004-03-09



Present: SB, CBJ, JC, NL, IBLR, NJW; CAO arrived later

1) Status for JEMX instruments

   JEM-X1 has been activated. Gain was as both half a year ago
   and one year ago. This value was a little too low so the HV
   has been increased by 1 step.
           
   Two change requests will be submitted 1) Upper PHA limit for JEM-X1
   to be increased from 750 to 1100 to cover the entire Xe-line at 30 keV
   2) The HV to be shifted downwards by 2 steps for JEM-X2
   
   It has been noticed that counts appear outside the active area of JEM-X1.
   This is very likely caused by events very close to the lower threshold.
   
   We must watch out for JEM-X2 behavior (e.g. like this) when the software
   changes are uploaded.
   
   Calibration results for both instruments i.e. the ARF should be available
   in a few days.
   
   We restrain from asking for diagnostic data in slews.
   
2) Results from Crab calibration
   
   Countrate with Crab on-axis      JEM-X1      JEM-X2
                                     110         120  cts/s bkg corrected
           The lower countrate for JEM-X1 is probably caused by the lower
           gain thus introducing a cut at low energies.
            
3) Actions from coordination meeting

   A revised instrument description primarily based on in-flight behavior
   is due July 2004.
   
   The switch-off altitude is now 75000 km when approaching perigeum.
   
4) Microstrip reports from Helsinki and CERN

   A behavior similar to the one observed in the JEM-X detectors (JEM-X2
   in particular) has also been observed in the lab depending upon
   specific glass material and strip metal. The metal seems to diffuse
   into the glass which changes (decreases) the conductivity. These
   reports have been put on the SDAST forum (by CAO).
   
/NJW


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Niels J. Westergaard
Danish Space Research Institute
Juliane Maries Vej 30, DK 2100 Copenhagen O
Phone: +45 35 32 57 05; FAX:  +45 35 36 24 75