BCAL Calibration
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Contents
CCDB Tables
base_time_offset
Full path : /BCAL/base_time_offset Rows : 1 Columns : 2 Location : Used in DBCALHit_factory.cc , it is added to the hit time Function : To centre the ADC and TDC times at 0 as initial calibration
ADC_timing_offsets
Full path : /BCAL/ADC_timing_offsets Rows : 1536 Columns : 1 Location : Used in DBCALHit_factory Function : To remove the 4 ns timing offset. (No longer needed after firmware fix for the F250 ADCs.)
TDC_offsets
Full path : /BCAL/TDC_offsets Rows : 1152 Columns : 1 Location : Used in DBCALTDCHit_factory , it is subtracted from the hit time. Function : To remove the 32 ns offset.
channel_global_offset
Full path : /BCAL/channel_global_offset Rows : 768 Columns : 1 Location : Used in DBCALHit_factory and DBCALTDCHit_factory , it is subtracted from the hit time. Function : Fine timing calibration
effective_velocities
Full path : /BCAL/effective_velocities Rows : 768 Columns : 1 Location : used in DBCALCluster_factory::overlap() (cluster with hit) Location : used in DBCALPoint_factory to calculate z and throw away points > 60 cm from BCAL Location : used in DBCALPoint to subtract the fiber-propagation-time from the time sum
z_track_parms
Full path : /BCAL/z_track_parms Rows : 768 Columns : 3 Location : Used in BCALPoint to get z position from delta_t
tdiff_u_d
Full path : /BCAL/tdiff_u_d Rows : 768 Columns : 1 Location : Used in DBCALHit_factory and DBCALTDCHit_factory, but we agree now that it should not be.
digi_scales
Full path : /BCAL/digi_scales Rows : 1 Columns : 3 Location : ASCALE not used, but TSCALE is
Timing Calibration Order
- 2 numbers (ADC, TDC) for each system (BCAL, FCAL etc.) Obtained by lining up the timing peak for all hits at zero. (plugin hl_detector_timing)
- Per channel: 1 number to move the TDC distributions mean to coincide with the ADC distribution mean. Average these offsets and apply to base time for TDC.
- Timewalk
- Make correlated offset to each end of the BCAL to set Z=0 at the center. Add time to one and and subtract same time to other end.
- Make correlated offset to each end of the BCAL to set global time correct. Add same time to both ends.
Concrete Steps in Calibration
macros are located at /group/halld/Users/dalton/BCAL/monitoring/macros/
- Remove 4ns ADC hardware offset (pass 1)
- Run reconstruction with BCAL_TDC_Timing plugin to produce the BCAL_TDC_Offsets/Deltat_raw/ histogram
- Run analysis script over output
- script for single run is macros/extract_ADC_Dt_Zcorr.C
- macros/monitor.py --adc4ns can be used to run over all runs
- Load constants to CCDB table /BCAL/ADC_timing_offsets using python macros/commit_CCDB.py -d output/ADCendDt/correction/ --adc
- Remove 32ns TDC hardware offset (pass 1)
- Set CCDB table /BCAL/TDC_offsets to 0
- Run reconstruction with BCAL_online plugin to produce the /bcal/bcal_Uhit_tdiff_raw_ave histogram (pass 1)
- Run analysis script over output
- script for single run is macros/extract_Uhit_tdiff.C
- macros/monitor.py can be used to run over all runs
- Load constants to CCDB table /BCAL/TDC_offsets using python macros/commit_CCDB.py -d output/tdiff/TDCcorrection/runs/ --tdc -v
- TDC timewalk correction (pass 2)
- Prerequisites:
- Remove 4ns ADC hardware offset
- Remove 32ns ADC hardware offset
- Run reconstruction with BCAL_TDC_Timing plugin
- Run analysis script over output
- script for single run is macros/fit_TDCtimewalk.C
- macros/monitor.py --timewalk can be used to run over all runs
- Load constants to CCDB
- Prerequisites:
- Position from end time-difference (pass 2)
- Prerequisites:
- Remove 4ns ADC hardware offset
- Run reconstruction with BCAL_TDC_Timing plugin
- Run analysis script over output
- script for single run is macros/fit_ZvsDeltaT_p1.C
- ./macros/monitor.py --position can be used to run over all runs
- Load constants to CCDB
- Prerequisites:
- Calibrate the point time offset from tracking (pass 2)
- Prerequisites:
- Remove 4ns ADC hardware offset
- Run reconstruction with BCAL_TDC_Timing plugin
- Run analysis script over output
- Linear fit (needs ~1M events per run)
- script for single run is macros/ExtractTimeOffsets.C
- macros/monitor.py can be used to run over all runs
- Quadratic fit (needs 5 files per run)
- Linear fit (needs ~1M events per run)
- Load constants to CCDB
- Prerequisites:
- Attenuation length and gain ratio (pass 3)
- Prerequisites:
- position calibration (pass 2)
- Run reconstruction with BCAL_attenlength_gainratio plugin
- Run analysis script over output
- Load constants to CCDB
- Prerequisites: