[Halld-pid] Time-of-Flight Meeting Minutes, July 17, 2014

[Mark M. Ito]

Folks,

Find the minutes below and at 
https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_July_17,_2014#Minutes 
.

   -- Mark
_____________________

GlueX TOF Meeting, July 17, 2014
Minutes

    Present:
      * FIU: Hussein Al Ghoul, Paul Eugenio
      * JLab: Chuck Hutton, Mark Ito (chair), Sasha Ostrovidov, Aristeidis
        Tsaris, Beni Zihlmann

Installation Update

    Sasha gave the report.

Scaler Read-Out

      * Discriminator-based scaler read-out is working now. Rates have been
        measured with the PMTs at 1250 V and a 30 mV threshold in the
        discriminators. See an example below.

    [20]Tof scalers 1250V snapshot1.png

      * Based on these scaler rates, there appear to be no light leaks in
        the system.
      * There were two channels with zero rate due to cables badly
        plugged-in. These have been fixed.
      * The correspondence between HV channels and discriminator channels
        was checked again yesterday using the HV GUI and scaler read-out.
        Sasha would like to repeat the exercise for the FADCs. We thought
        that the FADC-based scalers would be goof for this.

Cosmic Data Taking

    Sasha showed three events (see below). Bars colored in yellow indicate
    FADC hits, red dots show position determined from end-to-end time
    differences from the TDCs. Note that the TDC times have no calibration
    applied.

    [21]Tof view2.png

    [22]Tof view1.png

    [23]Tof view3.png

    Yesterday a long run of 20 k events was taken. It took about half and
    hour to take the data. The average event size is 80 kB.

Problems

    Over the course of the past week or so several problems were found and
    fixed (mostly).
     1. Last week an FADC with a bad bit was replaced. The new board had an
        old version of the firmware and did not play well with the data
        acquisition. A firmware upgrade fixed the problem.
     2. The HV GUI was in a frozen state that made it appear that the
        voltages were on when in fact they were not.^[24][1] Once this was
        realized it was fixed by restarting the IOC.
     3. At one point during calibration runs to set pedestals, the DAQ
        started crashing. This turned out to be due to a long configuration
        file name.
     4. Cables are plugged into the splitters in a haphazard way. Although
        the front-panel connectors are labeled "in", "A", and "T", these
        labels are not always respected. Since the splitter circuit is
        passive and three-fold symmetric this has no effect on operation
        but is confusing when trying to debug problems.

Near-Term Tasks

      * Sasha and Aristeidis will start a program to raise the voltages to
        their nominal values (determined on the bench at FSU) in small
        steps, checking discriminator rates as they go.
      * There is one channel with a dead ADC channel in cosmic data. This
        channel reported a nominal value in the pedestal runs previously.
        This problem is not understood at present.
      * Paul asked about implementing a system to monitor scaler rates
        independent of the DAQ state. The EPICS read-out of the
        discriminator scalers should be able to do this when it is
        implemented.

Action Items

     1. Ask about the status of the FADC scalers.
     2. Track down the configuration file name bug.
     3. Implement scheme to avoid confusion about HV status.
     4. Get the splitters cabled consistently.
     5. Ask about DAC value read-back capability on the FADC-250.
     6. Ask about the status of EPICS read-out of discriminator scalers.

Meeting Schedule

    We decided to meet weekly on Tuesdays at 10 am. Every other meeting
    will be focused on issues with installation/commissioning in the Hall.

References

   20. 
https://halldweb1.jlab.org/wiki/index.php/File:Tof_scalers_1250V_snapshot1.png
   21. https://halldweb1.jlab.org/wiki/index.php/File:Tof_view2.png
   22. https://halldweb1.jlab.org/wiki/index.php/File:Tof_view1.png
   23. https://halldweb1.jlab.org/wiki/index.php/File:Tof_view3.png
   24. 
https://halldweb1.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_July_17,_2014#note-0

-- 
Mark M. Ito, Jefferson Lab, marki at jlab.org, (757)269-5295