Gain Notes for Revolution 1192

This is one of the later revolutions in the mission where the calibration
sources have become so weak that for the best energy determination and
IC Gain History table is needed.

NB: Halfway through this revolution the satellite was hit by protons from a
coronal mass ejection which strongly suppressed the gain on the microstip plates
of both instruments, as well as strongly affecting the relative gain between the
science events and the calibration - causing a strong drop in the position of the
Xe line. Though this drop has been corrected by the IC table as much as possible,
and the Xe line now lies more or less at 29.6keV (within 5-6%) for spectra gathered
of the entirely plate, individual parts of the plate will have reacted very 
differently to the charging caused by the protons, and for this reason the gain
calibration cannot be considered particularly good. Also the unusually low gain
of the plates will mean that many events will have been lost to the onboard lo-end
cutoff filter, causing a loss of flux that cannot be corrected. For these reasons
the last third or so of the revolution is considered a BTI for BAD_CONFIGURATION
and this science data should only be used by people familiar with the instruments.
The BTI starts at IJD 4583.35 and continues to the end of the revolution.

 

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 else. The updated ISDC Instrument Characteristics
can be downloaded from
http://www.isdc.unige.ch/integral/download/osa_sw



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.

	
JEM-X1: 

The Xe line analysis performed using the IC table shows reasonable gain
correction with all science windows (except weak, or strongly grey-filtered SCWs)
in the pre-CME part of the revolution having a Xe level within 4% of the ideal. 
Similarly SCWs in the post-CME part of the revolution have Xe levels within
5-6% of the ideal. However, see the note above about thee effects of strong
plate charging by solar activity.
As usual, it is recommended that users
avoid the first few science windows for energy-sensitive applications.


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.



JEM-X2: 

The Xe line analysis performed using the IC table shows acceptable gain
correction with all except three strongly deviant misfitted science windows 
having a Xe level 
within 4-5% of the ideal for the pre-CME data and within 6-7% for the post-CME
Science windows. As usual however, it is recommended that users also
avoid the first few science windows for energy-sensitive applications.
The BTI beginnning at IJD 4583.35 also applies to this unit.

CAO 14/08/2012