Hall C Pedestal Runs and Determining FADC Thresholds

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This How-To discusses the necessary steps required in order to take a pedestal run utilizing the single arm DAQ's. Furthermore, the steps required in-order to determine the appropriate FADC thresholds are discussed.

Taking Pedestal Runs

  • Ensure that both single arm DAQ's are configured with the "fadcnothr" flag, which is activated via. of the pre-scale GUI, and the configuration has been saved
    • The FADC's can either be in mode 9 or 10
  • With both arms take at least 1000 cosmic or EDTM triggers and note the run numbers

Determining the FADC thresholds

  • The following example will illustrate the necessary steps required to determine the FADC thresholds for SHMS ROC 2
  • On the SHMS side, this procedure will have to be repeated for both ROC's 2 and 4
  • On the HMS side, this procedure only has to be executed for ROC 1
  • With the pedestal runs complete, open a terminal and SSH into cdaql1
ssh cdaq@cdaql1
  • Setup the hallc-online analyzer
  • Descend into the hallc-online hcana/podd directory
cd ../hcana/podd/hana_decode/
  • Exectue the tstfadc_main.C script
  • Input the appropriate configurations: raw data file location, run number, number of events, spectrometer name, crate number
Enter the location of the raw CODA file (raw, cache, raw.copiedtotape): raw
Enter a Run Number (-1 to exit): 1537 
Enter Number of Events to Analyze (-1 = All): -1
All Events in Run 1537 Will be Analayzed
Enter the Spectrometer Name (hms or shms): shms
Enter the Crate Number to be Analyzed: 2
  • If successful, the for file "fadc_data.root" will have been produced
  • In order to produce the threshold text file "thresholds.dat" one needs to execute the calc_thresh_hallc.C ROOT script
root -l ./calc_thresh_hallc.C
  • Input the appropriate configurations: spectrometer name, crate number, FADC mode, threshold in channels
Enter the Spectrometer Name (hms or shms): shms
Enter the Crate Number to be Analyzed: 2
Enter The Mode of The F250's: 9
Enter The Number of Channels Above Baseline the Threshold Should Be [40 (10 mV) recommended]: 40
  • A ROOT file "fadc_ped_data.root" will have been created which contains the final fits and determines the baseline values and thus the threshold values which are written to the text file "thresholds.dat"

Loading the FADC Thresholds

  • In order to have the CRL's load the appropriate FADC threshold files the newly created "thresholds.dat" file must be placed in the correct location
  • SSH into cdaql3 as coda
ssh coda@cdaql3
  • Descend into the respective thresholds directory for the appropriate ROC
cd coda/config_files/SHMS/ROC02/thresholds
  • Copy the newly created "thresholds.dat" into the current working directory
cp hana_decode/thresholds.dat .
  • Tag the "thresholds.dat" file with the current date
mv  thresholds.dat thresholds_DDMONYYYY.dat
  • Ascend one directory and symbolically link the newly created thresholds file as "thresholds.dat"
cd ../
ln -fs thresholds/thresholds_DDMONYYYY.dat thresholds.dat