Gain Notes for Revolution 1388

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!!!!!
This revolution is affected by a strong gain suppression caused by solar activity. 
The effect of this suppression is largely removed by the offline IC tables used to do
the gain correction. However, despite the relatively good gain correction for the individual
events, it should be remembered that extreme instrument gain can cause problems where the
events may be spuriously rejected by either the hi og lo-end rejection criteria, in a way
that cannot be corrected by the software. This will affect spectra produced in the second
half of the revolution. Users therefore should not read too much into changes in spectral
shape during periods of high solar activity. 

For JEM-X1 it has simply not been possible to correct for the 30% drop in gain the
instrument suffered, and therefore at BTI for bad instrument response has been declared
for this instrument alone. BTI (JEM-X1 only) IJD = 5169.1 to 5170.9. This BTI can be
overruled by a user GTI if you really know what you're doing, otherwise steer clear of
this data.

 

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-X2: 

The Xe line analysis performed using the IC table shows very good gain
correction with all SCWs, except the very first science windows and two outliers,
 having a Xe level within about 2% of the ideal. As usual however, it is recommended that users
avoid the first few science windows for energy-sensitive applications.

CAO 23/03/2014



JEM-X1: 

The Xe line analysis performed using the IC table shows very good gain
correction for the data before the BTI.All except the very first science windows having a 
Xe level 
within about 2% of the ideal. As usual however, it is recommended that users
avoid the first few science windows for energy-sensitive applications. The BTI that
covers the last 1/3 of the revolution means that the later data should not be used, 
especially for energy/spectral purposes.


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: Results coming soon.

CAO 24/03/2014