View source for Polarized Helium-3 Experiments

= [[Pol He-3 Analysis Resources]] =
{{:Pol He-3 Analysis Resources}}

= Calibrations =

I expect to break each detector/calibration out into its own wiki page as they mature, but for now I think it is best to work on this single (big) page until we have settled on a "good" template.

== Basic Template for each Detector/Calibration Procedure ==
For each detector subsystem we would like to capture/document the following information:
* A list of all (or at least the most useful) ROOT tree variables associated with this detector
* Description of the calibration algorithm (That is, how is it supposed to work -- what is the logic behind it?)
* Files involved in the calibration
** THc* or THa* modules that are needed/used
** Database files that will be modified
** Scripts that will be used
** Dependencies of this calibration
*** Reference time cuts should be verified
*** FADC 'hit selection' timing cuts should be verified
*** Calorimeter calibration relies on good optics calibration for momentum determination
*** If tight timing cuts are used, then the hodoscopes may need to be calibrated first, etc
*** ... etc
* Provide a step-by-step "Howto" that shows
** What commands/scripts need to be run, in what order.
** How do you verify that various cuts (ref times, trigger types, etc) are correct before you run the script(s)?
** What do you look for to verify that the code has run correctly after you run the script(s)?
* Common Pitfalls / Things to watch for
** I have found it useful in the past to provide a list of common symptoms and solutions that people may run into.

== Drift Chambers ==

== Hodoscopes ==
* The hodoscope calibration scripts are in <code>hallc_replay/CALIBRATION/hms_hodo_calib</code> and <code>hallc_replay/CALIBRATION/shms_hodo_calib</code>
* Carlos Yero wrote a pretty thorough guide to the calibration procedure on [https://hallcweb.jlab.org/DocDB/0009/000970/001/hodo_calib.pdf DocDB] as well as some [https://redmine.jlab.org/attachments/download/182/Carlos_ana_workshop2018.pdf nice slides] from the [https://redmine.jlab.org/projects/podd/wiki/Workshop2018 2018 analysis workshop]
* Here are the steps for the HMS. The procedure is the same for the SHMS.
# Set the flag <code>htofusinginvadc = 0</code> to NOT use the hodo parameters from the previous hodoscope calibration procedure. This flag is found on <code>hallc_replay/PARAM/HMS/HODO/</code> directory.
# Replay a run with 1–2 million events.
# In the directory <code>hallc_replay/CALIBRATION/hms_hodo_calib/</code>, run the following code:
#* <code>root -l ''timeWalkHistos.C(<run_num>)''</code>
#*This script takes as input the ROOTfile replayed and creates another ROOTfile with histogram objects that are used to perform the time-walk correction.
# To do the time-walk corrections, run the following code:
#* <code>root -l ''timeWalkCalib.C(<run_num>)''</code>
#*This script takes as input the ROOTfile containing the histogram objects produced by the previous script.  A parameter file containing the time-walk parameters will be produced at
#** <code>hallc_replay/PARAM/HMS/HODO/hhodo_TWcalib_runNUM.param</code>
#* Rename this file <code>hhodo_TWcalib.param</code>
# Replay the raw data file, once again (1 - 2 M events), with the updated time-walk parameters.
# In the hodoscopoe calibration directory, run the following code:
#* <code>root -l fitHodoCalib.C</code>
#* The first part of this script performs a linear fit on the time-walk corrected time vs. hodoscope track to determine the propagation velocity and the cable time difference across each paddle.
#* The second part of this code solves a matrix equation for the lambda parameters mentioned in [https://hallcweb.jlab.org/DocDB/0009/000970/001/hodo_calib.pdf Carlos's guide].
#* A parameter file containing the time-walk parameters will be produced at
#**  <code>hallc_replay/PARAM/HMS/HODO/hhodo_Vpcalib_runNUM.param</code>
#* Rename this file <code>hhodo_Vpcalib.param</code>
# Replay the raw data one last time, and check the hodoscope beta distribution.
#* You may have to apply a calorimeter cut (for example, <code>H.cal.etottracknorm>0.7</code>) to get a clean sample. A good calibration should have beta centered at 1.

== Calorimeter ==

== Gas Cerenkovs ==

=== ROOT Tree Variables ===

'''SHMS Heavy Gas Cherenkov (HGC)'''

*''phgcer_good_pped_vs_pmt'': Good Pulse Pedestal vs. PMT Number
*''phgcer_good_occ'': Good Occupancy
*''phgcer_good_mult'': Good Multiplicity
*''phgcer_npe'': Number of Photoelectrons (NPE) vs. PMT Number
*''phgcer_xytrack'': Tracking Y vs. X (positions in cm)
*''phgcer_x_vs_npe'': X vs. NPE
*''phgcer_y_vs_npe'': Y vs. NPE

'''SHMS Noble Gas Cherenkov (NGC)'''
*''pngcer_good_pped_vs_pmt'': Good Pulse Pedestal vs. PMT Number
*''pngcer_good_occ'': Good Occupancy
*''pngcer_good_mult'': Good Multiplicity
*''pngcer_npe'': Number of Photoelectrons (NPE) vs. PMT Number
*''pngcer_tot_npe'': Total Number of Photoelectrons
*''pngcer_trk_match'': Number of Tracks Matched vs. PMT Number
*''pngcer_trk_fired'': Number of Tracks Fired vs. PMT Number

== Aerogel (?) ==

== Optics ==

== EDTM ==

== BPM ==

== BCM ==

== ... ==