Psana reports in keV (using about 16 ADU/keV) as of run 21.
Each camera is calibrated at the ASC using our x-ray generator or using a sealed source, typically in situ. Currently the RGD is offline awaiting safety approvals. Cameras that have not been calibrated get an approximate constant calibration of 0.06 keV/ADU. The gain variation for the camera used to validate the full chain was reduced from ~4% to below 1%. While this is an absolute gain calibration, there are some systematics in fitting the photon peaks used in the calibration so users will want to check the scale of the photon energy in their reconstruction.
The gain file is deployed by makepeds the first time it is run. Makepeds looks for the pixel_gain directory under the experiment /calib directory. Psana and AMI use the gain file to report keV. Note that in AMI one should push the correct gain button if it's not on by default. Add discussion of hitfinding thresholds here. The psana raw object is not affected. Calib will return keV. One can find the pixel gains in psana using det.gain(evt).
Note that if a camera is swapped out during an experiment using the same detector number in the DAQ (ePix100.n) the pixel_gain directory for ePix100.n should be deleted and makepeds rerun - or discuss with an expert to preserve the old calibration information for the original camera.
For cameras with per-pixel gain files or that are calibrated post-experiment, we can deploy gain corrections retroactively for reanalysis. Please talk to the detector group.
Procedure
To make calibration information, do foo. Bhavna
To deploy calibration information to Mikhail's db, see /cds/home/p/philiph/psana/detdaq20/epix100/deployEpix100Gains.sh (make official Bhavna]