How to generate a new TPC pedestal

There are 3 steps in making a new pedestal for the TPC.
A. Run the TPC to generate the data for the pedestal analysis.
B. Analyze the data, and make the pedestal file.
C. Modify the configuration files so the new file is loaded.


Step A, Generate the raw data

This step is just a run of the TPC without zero suppression.
This step should be accomplished without beam.
  1. Start the DAQ control, and open "Trigger Prescale" in the configuration menu. Unselect all trigger prescales, and then select only the "pulser Prescale". Press the commit changes button.
  2. Open the "Detectors" window in the configuration menu. Press the "toggle TPC ped" button until the config file for the TPC changes to "tpc_ped.txt". Press the commit changes button.
  3. Press the start run button. If the run fails to start (ie: tpcppc[a-d] SIGCHLD errors), simply try starting again. If after three attempts to start the run, the DAQ still complains, then:
    1. Click on the STOP DAQ icon.
    2. Click on the Start Current DAQ icon.
    3. Goto step (3), unless you've already tried restarting the DAQ.
    4. If the DAQ is still not starting, check in the TV monitor that no more than 20 of the sticks are not working (dead sticks will appear as columns of lights in the TPC VME crates).
    5. If there are more than 16 sticks not working, try RelayOnOff -1, wait a few minutes and go to step (1). If that doesn't work, then (in order!):
      1. Power off the Low Voltage Power Supplies (the sticks) and the TPC VME crates.
      2. Power on the sticks.
      3. Power on the TPC VME crates.
      4. Goto step (1).

  4. Run a full subrun (the file must be 1GB). Write down the run number for the next part.

Step B, Make the Pedestal File

  1. Log into e907daq as the daq user.
  2. cd /ppcboot/common/home/mheffner/ped
  3. Figure out the location of the file generated in part 1. It should be on /data/0 or /data/1.
  4. GenerateTPCPedestal.csh {full path of file from step 3}
  5. Wait for script to finish (~10-20min).
  6. Put output of script into the logbook.
  7. Look for any error messages printed to the screen. If any, call or e-mail mheffner@llnl.gov -- 925-422-6762. If error messages, STOP and do not carry out any further steps.
  8. Look at the output and find the "number of sticks". This should be larger than 105. Look for the "Number of pad pads". This should be less than 200. If this is not true go back to Step A, and make sure than the TPC is working.

Step C, Configuring the DAQ to Use the New Pededstal File

  1. The pedestal file is generated in the working directory which should be /ppcboot/common/home/mheffner/ped if you are following these instructions.
  2. The name of the pedestal file has the run number. Find this file and note the full path of this file.
  3. Use emacs to open the file /ppcboot/common/usr/local/mipp/config/pro/tpc_config.txt. Find the keyword pedestal and rename the full-path file name to point to the new file name (note: the directory of the new file name is /home/mheffner/ped, _NOT_ /ppcboot/common/home/mheffner/ped).
  4. Repeat step 3 for the prepro and dev directories.
  5. Reverse stepA parts 1 and 2.
  6. Run the TPC and verify with online monitoring that the TPC is operating properly.