Subject: JEM-X Monday Meeting 2007-02-12
Date: Mon, 12 Feb 2007 13:42:09 +0100 (MET)

Participants: SB, JC, CBJ, NL, NJW.

JEM-X status (SB): Normal status. The temperature is low so the gain is
not so high. We are expecting a single step down of the high voltage
quite soon. Very low hot spot activity.
Dead anodes (JC): RAWX 18 or 19 has low activity. RAWX 20 is also low.
So in a single month we have lost 3 anodes.
Could this have something to do with the exposure to a particle radiation
dose at the end of each revolution.
This makes it more urgent to execute the step down in HV.

Upcoming Crab calibration (NL, SB): Detailed schedule not ready yet.
ISGRI has requested a staring to analyze the ghost pattern.
NL & SB will make a plan.

Dead time analysis (SB): The extra correction of the deadtime required
in conditions of high greyfilter setting follows the probability to
have a greyfilter event after an accepted event.
By manually defining the greyfilter setting this can be tested in
better detail than using the data from revolution 422. The staring
observation of the Crab is well suited for this test.
Also selecting various combinations of anode segments could shed some
light on the cause for the double-trigger origin.
We must plan the length of science windows to match the data transmission
and avoid a premature buffer flushing (Action SB).
We are approaching a better algorithm for the deadtime calculation but
it is not obvious how to incorporate this into the deadtime calculation
for the jemx science analysis pipeline. Action for CAO to come up with
a proposal (an SPR has been submitted already (?)).

/NJW


Additional note from Jerome:

Just a little precision. The 3 anodes lost in the past month are not the 3
above mentioned anodes as it could sound here. They are (chronologically):
RAWX = 144 on 7/01/07, RAWX= 48 on 25/01/07, and RAWX ~ 19 on 7/02/07.

Jérôme