Subject: JEMX Monday meeting 2004-05-17


Present: NL, CAO, SB, JC, ILR, CBJ, NJW

1) Status of instruments:
    JMX1 has shown high count rates, enough to provoke alerts. The reason
    turned out to be GRS1915+105 in the FOV (rev 193) with rapid variability.
    Unfortunately JMX1 was shut down 1.5 hours due to high count rate
    in IREM.
    
    JMX2: The reactivation will be a single orbit (rev. 208, June 26-29,2004).
    (SPI needs all its telemetry packets in rev 209, which includes the GPS).
    It was agreed that sending a person to ISDC for the reactivation is
    not required since the data analysis can be done just as well at DSRI.
    
    Lab model (FM1): no news.
    
2) Pixel Illumination Function:
    NL has been continuing the search for an adequte detector/collimator
    model. Among the parameters that can be adjusted are:
      - Collimator wall width
      - Tilt of collimator walls
      - Mask-detector distance (Canonical value is 3401 mm, NL gets 3393 mm
        is a better value, CBJ gets 3410 mm)
      - Small rotations of collimator, microstrip plate
      - Position accuracy as a function of energy
      - Curvature of collimator ("blown up" by gas pressure ??)
      
    SB suggested to separate the mask/collimator geometry effects from
    detector effects by using strong sources where background plays a
    minor role and analyze total number of counts.
    
3) Low energy efficiency study with data from calibration sources.

    SB has looked into the efficiency as a function of gain by plotting
    the intensity of the 5.9 keV calibration line (in two of the JMX1
    calibration spots) as a function of line position in PHA channels
    for various revolutions. This can be a tool for finding the
    efficiency of the detector as a function of gain.
    
    The Xe line can also be extracted from the calibration source events
    to check if the high rate/low gain effect is present.
    
4) No news about ISDC representative.

AOB: Extra ISWT meeting about how to handle Galactic Center core program
     observations vis-a-vis Russian proposal. NL will go there on wednesday
     (May 26, 2004) but must be in Nyborg the following day. NL suggests that
     SB covers the ISWT May 27.
     
/NJ
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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