Progress report on start counter and tagger electronics:
The start counter has been in Hall B this week. The detector was
turned on and looked OK, however they did not have access to DAQ
for further testing due to the Hall A mud slide.
Luc reported on the status of the tagger electronics. The E
counters will be done by today. 23 of the 26 ADML disc. boards
have been returned from Philips, and will be installed during
maintenance time during e1. Other than the ADML's, the tagger
electronics will be completed by Monday 2/9. Tagger trigger logic
needs to be tested.
Tagger test next week:
Elton reported on plans for a short tagger test next week. When
the beam is tuned to the tagger beam dump at the start of e1 the
radiator will be inserted. The plan is to look at the timing of
TOF relative to tagger, and to test the following triggers,
i. Tagger Master OR
ii. TOFSec1and4.trg (reduced sensitivity to cosmics)
iii. AsynchForwardTOFSect1-6.trg*Master OR
For the first two triggers only a small fraction of the data will
have events in both CLAS and tagger, large prescale factors required.
For the third trigger we need to use the asynchronous input to the
level 1 trigger. We need the crates for the Tagger T-counters,
the T-counter scalers, and for the TOF scintillators operational.
New prescaling scheme:
Thought has been given to a prescaling plan that doesn't rely on
prescale factors (unknown accuracy?) within the trigger
supervisor. Elton presented a plan that uses a VME output register
that goes to ECl/TTL to Fan in/Fan out to the veto inputs
of the T_left*T_right*E coincidence gates. The advantage to this
plan is that we're prescaling at the level of the T-counters, and
the T counter scalers are also prescaled. The only hardware we
need for this are two units of Phillips 757 Fan in/fan out and
some cables. This could easily be ready for the start of g1. There's
the issue of how the prescale factors get into the data stream, and
the frequency of the VME output register. To minimize deadtime
the VME resister should probably run at about 1 Mhz.
Commissioning schedule:
The target and photofission installation, and cerenkov removal
will happen 3/10-3/17. After consultations with the g1 spokespersons
and g5 collaborators it was decided to split the available
commissioning time in March and April between tagger commissioning
and g5, with approximately 8 days each.
Date Activity
March 10-17 Target and fission installation, cerenkov removal
March 18-23 Tagger commissioning
March 24-25 Maintenance
March 26-27 Moeller tests
March 28-31 Facility development
April 1-2 Tagger commissioning
April 3-6 Photo-fission
April 7-8 Maintenance
April 9-12 Photo-fission
Arpil 13 Remove fission detectors, start g1.
We will ask for time during facility development for tagger
commissioning, but we shouldn't plan on getting it. Arne will probably
need a day to pull the photo-fission detectors out of the beamline
and to get the vacuum line up.