KAON-LT analysis instructions

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Replay:

  • We would like the detector check replay to be done on first 50,000 events of every run, and compare plots with the standard ones in the binder. In addition, we want physics replay to be done on every run in its entirety. K+ plots such as missing mass, t, W , Q^2 and φ should be checked for anomalies. Replay instructions are below.
  • Keep the file standard.kinematics up to date with the spectrometer settings for every configuration, so that the physics replay generates meaningful quantities. Use the beam energy determined from the arc measurement in the file, and the spectrometer angles from the TV.
  • Shift leaders are asked to keep a running total of the number of e − K coincidence events falling within the missing mass and fiducial volume cuts set in the physics replay kumac, so that we can better estimate when to move to the next setting.



Detailed Online Analysis Instructions



At a new kinematic setting, edit the file standard.kinematics in the DBASE/COIN subdirectory to add the current kinematic information:

  • First, add a comment to indicate the kinematic setting.
  • Then enter the range of runs the kinematics are valid to (enter 9999 as upper range if ongoing).
  • Next, enter the beam energy determined from the arc measurement, the target mass in amu (available at the top of the file), and the spectrometer angles from the TV.
  • Next are the central momenta of the HMS and SHMS, followed by the mass of the particle each arm should detect (the leading letter indicates which arm: p = SHMS, h = HMS).

After 50,000 events have been taken, check the detectors:

  • On cdaql1, type go_analysis to enter working directory.
  • Type ./run_coin_shms.sh to automatically replay the most recent run and launch SHMS detector GUI. Compare with the histograms in the golden run binder.
  • Type ./run_coin_hms.sh to repeat the process for HMS detectors.
  • For reference, all histos are saved in the HISTOGRAMS subdirectory.

After the run is over, do coincidence physics replay:

  • On cdaq, type go_analysis to enter working directory.
  • Type cd UTIL_KAONLT/ to enter K+ analysis directory.
  • Type KaonYield.sh run_number nevents for partial replay, leave nevents blank for full replay. The script will do scaler replay followed by coincidence replay.
  • When replay is done, you will be prompted to enter a current threshold (typically 5 μA) and the prescale factor used (typically 1).
  • A GUI will launch with physics distributions. Compare to the simulations in the binder, and record the number of K+Lambda events on the run sheet.
  • Displayed histograms, plus several others including e-pi+, e-K+ and e-p coincidences are stored in the UTIL_KAON/Histograms/ directory. Efficiency information in the scripts_KaonYield/ directory.
  • Enter the run details in the run log at https://hallcweb.jlab.org/wiki/index.php/Kaon_LT_Run_List

Heepcheck runs: have a special analysis script:

  • On cdaq, type go_analysis to enter working directory.
  • Type cd UTIL_KAONLT/ to enter K+ analysis directory.
  • Type peepYield.sh to run the script and launch the GUI.
  • Anomalously large missing momentum components or missing mass either indicate an issue with the entries in standard.kinematics or some other problem with the spectrometer or beam settings