Time-of-Flight/Start-Counter Meeting
Minutes

   FIU: Seema Dhamija
   FSU: Sasha Ostrovidov
   JLab:  Eugene  Chudakov,  Mark Ito (chair), Elton Smith, Simon Taylor,
   Tim Whitlatch

Review of Last Meeting's Minutes

   We review the [17]minutes from the August 7 meeting.
     * Last  week Maurizio Bertoldi and Paul Eugenio came up from FSU and
       visited with Tim. They discussed mechanical support issues for the
       time-of-flight.
     * We  briefly  SiPM  trouble  seen in Hall B. Elton noted that those
       problems were after running with an electron beam and they may not
       be an issue for us. Dose studies should be done in any case.


Time-of-Flight Status

   Sasha  O.  reported on recent progress. They have continued to work on
   the  problem with one of the Hamamatsu not getting to 100% efficiency.
   Switching  electronics  does  not  change  the  behavior. If PMT's are
   swapped  the problem moves with the PMT. Paul is trying to get another
   Hamamatsu  H10534. They are also trying to measure the adc spectrum as
   the  trigger  counters  are  moved  along  the  length of the counter.
   Amplification was suggested; something to try.

Start Counter Status

   Seema  gave  us an update. The 3 mm thick scintillator is being tested
   is  being  tested  with  an  LED  pulser  (120  ps  pulse  with  10 ns
   rise-time).  A  fine-mesh PMT is being used on one side, a SiPM on the
   other. The latter is coupled directly to the scintillator.

   Studies  with  with cosmics rays will be done with a 2 cm wide trigger
   counter.

   Werner  has  been  making  plots of of radiation length as function of
   polar angle for the current geometry.
     _________________________________________________________________

   recorded by [20]Mark Ito

Retrieved from
   "http://www.jlab.org/Hall-D/software/wiki/index.php/Time-of-Flight/Start-Counter_Meeting%2C_August_21%2C_2009"

References

  17. http://www.jlab.org/Hall-D/software/wiki/index.php/Time-of-Flight/Start-Counter_Meeting%2C_August_7%2C_2009
  20. http://www.jlab.org/Hall-D/software/wiki/index.php/User:Marki