Gain Notes for Revolution 1225

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.
 

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 very good gain
correction with all except the very first science windows, and a cluster of
outliers at the beginning of the revolution,  having a Xe level 
within 23% of the ideal. Only a few real data points lie outside 2%. 
As usual however, it is recommended that users
avoid the first few science windows for energy-sensitive applications.
The cluster of outliers/scatter at the beginnning of the revolution suggests either a period
of grey filtering, or some lingering charge/noise on the plate from the radiation belt passage.
The behaviour of calibration source four and the (mis)fit to the problematic data points shows
the strong variation in countrate that produced this instrument noise, and how sensitive the
unused/damaged fourth calibration area is to plate charging due to high countrate.


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 very very good gain
correction with all except the very first science windows, and acouple of misfitted
outliers having a Xe level 
within 2-3% of the ideal. As usual however, it is recommended that users
avoid the first few science windows for energy-sensitive applications.
To a lesser extent this unit also shows the negative effects of countrate variations
at the beginnning of the revolution.

CAO 30/10/2012