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Gain intercalibration procedure at SPS
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The procedure for CAL gain intercalibration at PS and SPS uses the [CalTuple|http://www.slac.stanford.edu/exp/glast/ground/software/status/documentation/EngineeringModel/latest/CalXtalResponse/latest/] of all 4-range readout runs taken at different scanning positions. *It is based on the signal (in MeV) stored in the CalXtalFaceSignalAllRange\[tower\]\[layer\]\[column\]\[side\]\[range\] array*. At SPS we checked the constants obtained at PS (towers 2 and 3), especially for HEX8 for which the lever arm in energy deposit was not so large. We also calibrated tower 1 for which LEX1/HEX8 was not well calibrated at PS. |
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This procedure yielded a list of selected runs for each log end ratio and better results, see e.g. T2-L6-X5-S0. It was applied to all log end and the results were stored in the following files: tower 1, X logs, tower 1, Y logs, tower 2, X logs, tower 2, Y logs, tower 3, X logs, tower 3, Y logs. In these files the 96 first pages are (one per log end) show the same kind of plots as those described above, for each log end, and the 3 last pages show the distributions of the slope, chisquare and the crossing value of the linear fit of the 96x3 profile histograms (the crossing value is in MeV and the range of the plots is +-1% of the R_i+1 spectrum maximum). From these files tower 2 appears to be perfectly calibrated. In towerThese results that tower 2 is correctly calibrated. In tower 3, Y logs are correctly calibrated as well, while 2 outliers (T3-L2-X7-S1-R_1/R_2 slope, T3-L6-X4-S0-R_2/R_3 slope) are observed as underflows in the slope distributions of X logs, also visible in the crossing value distribution with large errors; the individual plots show that the second outlier is due to poor statistics, while the first one should be looked at in much detail (actually we assumed that the calibration is fine, like for all other logs in tower 3...). Finally in tower 1, X logs calibration constants are reliably obtained (1st and 3rd slopes very close to 1, and 2nd slope R_1/R_2 ~1.087 with a RMS of ~0.03), except in layer 0 for R_2/R_3 slope (not used anyway in data analysis) due to poor statistics at high energy since showers start deeper in the CAL in the absence of TKR in front of the 1st CAL module; as for the Y logs in tower 1, calibration constants are also reliably obtained, except T1-L7-X11-S0 which exhibits a strange behaviour (R_1/R_2 and R_2/R_3 slopes, forced to 1...).
In conclusion, only R_1/R_2 (LEX1/HEX8) slopes for tower 1 were propagated in the DB by modifying the HEX8 MeV/DAC.
Update of CAL calibration constants in DB (Aug 7th) pdf resumé
- A new CAL pedestals (700000953) has been recorded. Zach produced a set of xml files (see $LATCalibRoot/CAL/CU06):
cidac2adc.digitization-latte-v1r030603p2_700000446_digi_DIGI.xml
muonAsym.digitization-latte-v1r030603p2_700000276_digi_DIGI.FLIGHT_GAIN.xml
muonMPD.digitization-latte-v1r030603p2_700000276_digi_DIGI.FLIGHT_GAIN.xml
muonPeds.digitization-latte-v1r030603p4_700000953_digi_DIGI.FLIGHT_GAIN.xml
tholdci.CU06.FLIGHT_GAIN.08022006.xml
- After intercalibration of LEX1 and HEX8 (from runs 700000700 to 700000750) the asymmetry and MevPerDac files have been updated:
muonAsym.digitization-latte-v1r030603p2_700000276_digi_DIGI.FLIGHT_GAIN_correct_v2.xml
muonMPD.digitization-latte-v1r030603p2_700000276_digi_DIGI.FLIGHT_GAIN_correct_v2.xml
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