Gain Notes for JEM-X2 Revolution 902
	

JEM-X2:

A quite normal revolution with fine gain fitting. All the data from 
this revolution should be useable. The Xe line analysis confirms the very
good gain calibration for this revolution with all except the very first Science
Windows having a Xe line position within 2% of the ideal value.
As always, however, it is suggested that
users avoid the first few science windows in each revolution since this is
where the instrument warms up and gain variations across the plate settle down.



CAO 16/03/2010

	
JEM-X1: 

This Crab calibration revolution sees JEM-X1 being turned on for the
first time is several months. The revolution begins with a very cold instrument
which slowly heats up in the course of the first day to a very high temperature
of 27 degrees (20-23 degrees is a better operating temperature for JEM-X1).
During the very first science windows the instrument is regaining it's mature
microstrip plate charge distribution, and energy determination is very poor
indeed. By the time the instrument has fully warmed up the strong non-linear
gain effect of the aged instrument is apparent, so that the Xe line position
falls far too low (around 28.2 keV). To correct these problems with the
automatic gain calibration and energy correction and IC gain historyt table,
corrected offline, must be used.

To get optimal results with this revolution it is necessary to use the IC gain history
table that has been created offline at DNSC, instead of the gain history table
created automatically by OSA. If you have the newest package of IC files from ISDC
and these are correctly installed, OSA will find the IC gain history table automatically
and you don't need to do anything. However, if you don't have the IC gain table
package from ISDC you can download the table from the gain history archive by
anonymous ftp through the link provided. Download the table to some suitable
subdirectory for your analysis, then set the hidden OSA parameter gainHist:
gainHist="<my subdirectory>/<IC filename>". These files are used instead of the
automatically generated gain history tables wherever there has been an unusual or
non-linear behaviour of the detector gain.


Calibration source number 4 (purple/orange) is no longer
used for calibration purposes since an anode strip directly under the source
has broken and no useable signal comes from this area of the detector any
longer.

Using the IC table gives Xe line results for which all SCWs except the very
first ones are within 3% of the ideal value. As always it is recommended that
users do not use the first SCWs in the revolution for energy-sensitive
applications since the instrument is still warming up and settling down.


CAO 29/04/2010