How to Set EDTM Frequency with the DVCS Pulser

From Hall A Wiki
Revision as of 22:06, 13 October 2021 by Skbarcus (Talk | contribs)

Jump to: navigation, search

return to Shift How-To

The EDTM (electronic dead-time monitor) is controlled via a DVCS pulser in the bbhodo crate. This pulser creates a pulse, normally 20 Hz, that is injected into the trigger decision logic of BB and HCal coming from their summing modules. This will create a signal that looks like a real trigger, however there will be no useful data associated as the trigger is simply from a pulser. To distinguish these fake events in later analysis copies of the EDTM pulser are sent into F1TDCs of both BB and HCal. So, if an event in either detector has signal in the F1TDC channel that contains a copy of the EDTM pulser we know that this was an EDTM event and not a real physics trigger. We can then find the electronics dead-time, coupled with the DAQ dead-time still, by comparing the number of EDTM events BB and HCal saw versus the number of EDTM pulses in a scaler.

  • Controlling the EDTM DVCS Pulser:
  1. Log on to sbs-onl@adaq1 and navigate to the /adaqfs/home/sbs-onl/bbhodo/ directory with the usual sbs-onl password.
  2. Make sure the environment is setup correctly. echo $REMEX_CMSG_HOST should return adaq2 and echo $REMEX_CMSG_PASSWORD should return SBSDAQ. If either are not correct run the following (default $REMEX_CMSG_HOST currently returns 'tedbbdaq' which needs to be changed).
 export $REMEX_CMSG_HOST adaq2
  1. Use remex to give commands to bbhodoROC5.
  2. Load the DVCS pulser library.
 remex -d bbhodoROC5 linuxvme/dvcsPulser/
  1. Initialize the DVCS pulser. The first argument is the address of the pulser. Note: initializing the pulser will turn its output off if you wish to disable the pulser.
 remex bbhodoROC5 'dvcsPulserInit(0x1300,0)'
  1. Enable the pulser output.
 remex bbhodoROC5 'dvcsPulserEnable(0x1d)'
  1. Set the pulser frequency to one of the following rates given in Hz: 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, 2000, 5000, 10000, 20000, 50000, 100000, where the argument is the frequency.
 remex bbhodoROC5 'dvcsPulserSetFrequency(20)'