Final Run 9 BSMD Absolute Calibration


The Run 9 BSMD absolute calibration was made using few-GeV TPC-identified electrons from pp500 running, and has two pieces.  The first is a new CALIBRATION table in the database which will be used in the EMC slow simulator to improve the agreement of of MC ADC with data.  This table starts by combining the previously-determined strip-by-strip relative gains with the existing values in the table.  This is then multiplied by the ratio of the slope of a linear fit to the mean cluster ADC distribution from few-GeV isolated data electrons to the same slope in simulated electrons, where the slope is calculated in four different eta bins.  The second piece is a new GAIN table in the database which allows ADC values to be converted to energy deposited in the BSMD.  This table was determined by combining the strip-by-strip relative gains with a similar ratio as above, but using mean cluster energy deposited in the BSMD instead of reconstructed ADC values (the electron samples used for data and MC were the same) and it is calculated in ten eta bins instead of four.  Both tables are currently in the database with flavor "Wbose2": it is hoped that eventually the CALIBRATION table will migrate to flavor "ofl", but the GAIN table will have to remain "Wbose2" because it is currently used (with values all equal to 1) in some codes to determine the change in the BSMD calibration over time.  While producing two tables which are in some ways overlapping and one of which can never be flavor "ofl" is not an ideal solution, it allows us to avoid making any modifications to currently existing code (in particular the StEmcSimulator) and allows people who prefer to think of reconstructed energy from BSMD ADCs as being the full particle energy instead of the energy deposited in the BSMD to continue as they were with no change.  For more details, please see:

1. Overview of the method

2. Final cut list and data-MC comparison

3. Overall Summary

Additionally, a link to the 2009 BSMD Calibration note will be added here once it is completed.

See also a brief presentation on why we chose not to include the BSMD gas pressure in our analysis.