Gain Notes for Revolution 1181

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.

N.B. This revolution was affected very strongly by idiopathic gain suppression on the
microstrip plates of both units (as seen in the science data, Xe line) but not at
all in the calibration spectra, which is why the end of the revolution has huge
scatter and many wild outliers.
 

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 good gain
correction for the first half of the revolution, with all  science windows 
having a Xe level within 2-3% of the ideal. The second part of the revolution
was heavily affected by gain suppression of an unknown cause, so that apart from
some misfitted outliers, the Xe position is within about 3-4% of ideal.
 As usual however, 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 very good gain
correction for the first half of the revolution, with all except the very 
first science windows having a Xe level 
within 1-2% of the ideal. The last part of the revolution is strongly affected
by the unexplained gain suppression, and here the Xe level is only good to
about 3-4% of the ideal.
As usual however, it is recommended that users
avoid the first few science windows for energy-sensitive applications.

CAO 25/06/2012