Finding LAC value with nomSciOps runs
Berrie and I (David Sanchez) had a look at how the code works with nomSciOps runs.
We found that some events have direct diode deposit on the opposite face. This case is not yet taking into account in the code that generated LAC histogram leading to bad LAC value.
This plot is the LAC value distribution for run 077018222. X axis is p0-Ped . We used the following configurations files:
PED : digitization-licos-v3r9p3_077014293_digi_DIGI.FLIGHT_GAIN.calPed.txt
MuSlope : digitization-licos-v3r9p3_077014313_digi_DIGI.FLIGHT_GAIN.muSlope.txt
All files can be found at /afs/slac.stanford.edu/g/glast/ground/releases/calibrations/CAL/LAT-flight_gain/
This is the LEX8 signal histogram for tower 9, layer 4, crystal 0 Face 1. X axis is ADC value . This crystal is one with weird LAC value. This is due to non-empty low energy bin. In fact the fitting procedure use the first non-empty bin as a reference. In such case, this first bin is not relevant. To tackle this issue we have modify the code that generate LAC histograms to cut the events with direct diode deposit.
the following plot are LAC value distribution and LEX8 signal histograms for the same run and crystal
It remains no bad value. It is probably useful to modify all scripts generating LAC, FLE, FHE histograms to take this case into account.
A look at the new version of the code.
Zach made some changes in the code to be less sensitive to the trigger noise. Here is part of his mail.
Basically I have replaced David's 'firstNonZeroBin' variable w/ a 'firstBin>15%max' which should serve the same purpose - it should avoid sensitivity to any noise triggers in the LAC circuit.
Also I have a gemDeltaEventTime < 500 microseconds cut in genLACHists.exe which should also reduce noise hits.
Also I restricted the threshold fit parameter, making it a little more stable.
I use the new code with the same configuration files and the same run.
LAC value distribution for run 077018222. The new code greatly improve the fit. Only few LAC value are obviously not found.
LEX8 signal histograms for 2 channel badly fitted
LEX8 signal histogram for crystal T3L5C8, the same as above.
Impact on LAC runs, TVAC run 077016907.
There is no major impact. Fitted LAC values remain almost the same.
Python script for LAC, FLE, FHE
I wrote a python script to easily run the code (genHists* and fit*) for LAC, FLE, FHE. It also plot threshold distribution if asked.
The script is located here : /a/sulky36/g.glast.u33/sanchez/CALcalib.py