Minutes 060609

Notes for item 2, tagger and trigger timing, etc:

1.  We should install He bags;  need official request to H-B for this and other beamline components
    incl. radiator thickness, collimator size, etc.

2.  Tagger trigger timing (thanks to Eugene Pasyuk):
  20 ns      transit time in PMT's
  50 ns      cable to CFD
  10-15 ns   internal CFD
  5 ns       cable to L-R coincidence module
  5 ns       internal coincidence module
  10 ns      cable to Master OR module
  20 ns      internal Master OR
  80 ns      cable to forward carriage
  -----
  200 ns

Note that photon flight time to alcove is approx 100 ns.  If I recall, Richard said RadPhi has both
250 ns cables and 80 ns cables running from the alcove to the RadPhi racks.

3.  Tagger uses LeCroy 1877 multi-hit and CAEN pipelined TDC's; both run in common-stop mode

4.  CAEN V792 ADC (BCAL readout) is slowest and sets front-end busy time.  May skip busy and just 
    use front-end-busy-timer in TS, as V792 has fixed digitization time of approx 7 microsec.