Data Analysis - Commissioning Tasks

Pedestal Defaults

The FADC250 modules used for data analysis automatically determine the pedestal by looking at the first 4 samples of the programmable lookback (PL), which corresponds to the same four samples of the programmable trigger window (PTW). The average of the fisrt four samples is saved as the Pulse Pedestal, which is saved in the EVIO file and used inside hcana to calculate the pulse integral PulseInt = PulseIntRaw - PulsePed. When any of the first four samples are above threshold of the PTW, the FADC250 sets the Pulse Pedestal to zero. Prior to April 2020 hcana would throw out events, which had a PulseAmpRaw==0. In an April 2020 update, Mark Jones added 'cut' parameters to set a default pedestal for all ADCs that are not the hodoscope. The change for the hodoscope is outlined in the below for the ScintillatorPlane::ProcessHits function of the THcScintillatorPlane Class.

THcScintillatorPlane.cxx Changes

ScintillatorPlane::ProcessHits

• Selects first TDC PMT hit within the TDC_min and TDC_max windows.
• Old code
  • If Raw ADC Amp = 0 , then do not use hit.
  • First ADC hit within ADCTDC_min < TDC_time – ADC_time < ADCTDC_max
  • If no ADC hit is found then PMT hit is not “good”. Need both ADC and TDC info for “good” PMT hit.
• New Code
  • If Raw ADC amp = 0, then use hit and test ADC hit setting ADC Amp =200.
    • Adc Amp=200 sets the timewalk correction to zero.
  • First ADC hit within ADCTDC_min < TDC_time – ADC_time < ADCTDC_max with largest ADC value
  • If none found then selects one with smallest TDC_time – ADC_time .
  • So if there is an ADC hit for paddle PMT, then it will set “good” PMT hit if there is TDC PMT hit.

Mark Jones DocDB ref. 1055 v2.

hcana April-2020 Changes to Other Detectors

• The FADC uses the first four samples of the FADC time window to determine the pedestal.
• In a pulse is detected in the first four samples
  • FADC sets the raw pulse amp for all pulses in the window to zero
  • The pedestal is not the true pedestal for later pulses in the window.
• Old Code : Throw out the detector hits when found PulseAmpRaw ==0
• New Code: When PulseAmpRaw ==0
  • Uses an average pedestal value, PedDefault, that is a parameter for each detector PMT.
  • Calculates the PulseInt = PulseIntRaw – PedDefault
  • Set PulseAmp=0. Can be used as tag to look for these events.
  • Hodoscope detector is special. It does not use PedDefault. The PulseAmp is used for time walk correction. So when PulseAmpRaw==0, set PulseAmp=200.

Mark Jones DocDB ref. 1056 v1.

Analysis Procedure (XEM)

• Ensure you have ROOTfiles/<detector>/CALIBRATION/ in hallc_replay_XEM top directory
• Ensure you have REPORT_OUTPUT/<detector>/CALIBRATION/ in hallc_replay_XEM top directory
• Ensure you have loaded the XEM2 software with the setup script.

1. Run the replay and exit when finished

   hcana[0] .L SCRIPTS/<spectrometer>/CALIBRATION/replay_setPedDefault_shms.C
   

   hcana[1] replay_setPedDefault_<spectrometer>(RunNumber,Nevents)

2. Save the ROOTfiles/<spectrometer>_setPedDefault_runNo_Nevents.root to the JSROOT web location

   Add the name of the output root file to the root file viewing script

3. Run the set_peddefault for the given detector

   hcana[0] .L CALIBRATION/set_peddefault/run_ped_default.C
   

   hcana[1] run_<spectrometer>_ped_default("<path_to_file/replayed_file.root>")

4. Copy the determined pedestal defaults to the relevant 'CUT' files by hand (First time)
   1. If the pedestal defaults have not changed significantly, make note and keep the existing defaults.
   2. If the pedestal defaults have changed, add a new 'CUT' file with a relevant name and associate it with the run number range.

Online Running Information
Responsibility	Check Frequency	Reporting Sections
Casey Morean	Every 100 runs	Commissioning Activity
		Page on XEM Web JSROOT