Data Analysis - General Parameters

General Parameters

General parameters are broken into two categories; parameters that are not spectrometer specific, and those that are spectrometer specific.

• All general parameters are included using the general.param file, which is spectrometer specific. The general.param file is located at:

DBASE/<spec>/

• Global general parameters used for the hall C beamline and debug modes are stored in:

PARAM/GEN/ directory.

• Spectrometer specific general parameters are included at:

PARAM/SHMS/GEN/

PARAM/HMS/GEN/

Non-Spectrometer General Parameters

As the name implies, these do not deal with the specific spectrometer, but rather the beamline or target componenets. There used to be energy loss parameters included in this directory for the old Fortran analyzer. The C++ analyzer no longer calculates energy loss, so the variables associated with energy loss have been removed.
The main parameters of this section are the BCM scalers and the BPM positions from HARP scans and the raster conversions. These aspects have their own devoted analysis section.

Global GEN Files

• PARAM/GEN/genflags.param

  Only includes the gen_run_starting_event parameter.

• PARAM/GEN/gdebug.param

  No used parameters

• PARAM/GEN/gtarget.param

  No used parameters, Eloss not included in hcana. Eloss handeled in rc-externals

• PARAM/GEN/gscalers.param

  Calibration of scaler BCM branches. Must be set before running the BCM calibration procedure.

• PARAM/GEN/gbeam.param

  Calibration of beam position on target and raster settings.

gscalers

The gscalers.param file currently only includes BCM calibration information. In theory, there could be other scaler calibrations here, but it is unlikely this will change. BCM calibrations are typically applied on a specified run-range based on a BCM calibration run. The gscalers.param Main Parameters:

• gNumBCMs = 6
• gBCM_Names = " BCM1 BCM2 Unser BCM4A BCM4B BCM4C"
• gBCM_Gain = 4795.0, 4092.0, 4000.0, 13020.0, 2042.0, 6238.0
• gBCM_Offset = 250300.0, 250200.0, 393000.0, 432.4, 204.9, 127.8
• gBCM_Current_threshold = 5.0
• gBCM_Current_threshold_index = 3

The naming of these variables is different than any other variable in hcana because of their capitalized letters. Additionally, No other detector has space-separated names like this one does.

gbeam

The gbeam parameter files include information related to the surveys of absolute beam position using HARP scans and the EPICS RAW BPM variables. The naming of these parameters is self-explanatory, but the sign on many of the parameters is not straight forward because the difference in coordinate systems in the hall. Refer to the BPM calibration procedure for specifics on this.

Hall C EPICS RAW BPM values in units of cm

gbeam_{x,y}

gbeam_{xp,yp}

Hall C BPM A, B, and C, slope and offsets based on HARP scans

gbpm{x,y}{a,b,c}_slope

gbpm{x,y}{a,b,c}_off

positions of BPMs relative to target determined from Survey and Alignment

gbpma_zpos

gbpmb_zpos

gbpmc_zpos

Fast Raster Calibration Constants

gusefr = 1

flag if 1 fast raster data used with average beam pos and angles in calculating beam position. If 0 then only use average beam pos and angles in calculating beam position

gfr_cal_mom

gfr{x,y}{a,b}_adc_zero_offset

gfr{x,y}{a,b}_adcpercm

positions of FR magnets relative to target (cm)

gfr{x,y}_dist

Spectrometer General Parameters

As the name implies, these parameters deal with the specific spectrometer parameters. These are more general parameters than detector-specific parameters, which are covered in the next page of data analysis. The HMS and SHMS has its own separate GEN parameters located in:

• PARAM/SHMS/GEN/
  
• PARAM/HMS/GEN/
  

SHMS GEN Files

• PARAM/SHMS/GEN/pcana.param

  Magnetic optics matrix elements used for reconstruction of target variables. Also includes SHMS path length.

• PARAM/SHMS/GEN/pdebug.param

  Dump flags used to debug tracking algorithm for the SHMS. Number of events with different values before resetting pedestals.

• PARAM/SHMS/GEN/shmsflags.param

  Momentum, angle, and delta corrections as well as saturation corrections applied to the central momentum and reconstructed variables.

• PARAM/SHMS/GEN/ptracking.param

  Parameters used to tell hcana which tracking algorithm to use, and which cuts are to be applied to select good tracks.

• PARAM/SHMS/GEN/p_reftime_cut.param

  Location of reference time cuts for the specified detectors. Refer to the Reference time and timing windows section for more information.

HMS GEN Files

• PARAM/HMS/GEN/hcana.param

  Magnetic optics matrix elements used for reconstruction of target variables. Also includes SHMS path length, detector-specific fiducail volumes and corrections.

• PARAM/HMS/GEN/hdebug.param

  Dump flags used to debug tracking algorithm for the HMS.

• PARAM/HMS/GEN/hmsflags.param

  Momentum, angle, and delta corrections as well as saturation corrections applied to the central momentum and reconstructed variables.

• PARAM/HMS/GEN/htracking.param

  Parameters used to tell hcana which tracking algorithm to use, and which cuts are to be applied to select good tracks.

• PARAM/HMS/GEN/h_reftime_cut.param

  Location of reference time cuts for the specified detectors. Refer to the Reference time and timing windows section for more information.