Attending: W. Briscoe, R. Schumacher, D. Carmen, B. Mecking,
E. Smith, D. Jenkins, A. Yegneswaren, B. Asavapibhop, S. Barrow,
G. Mutchler, S. Taylor, R. Miskimen, S. Phillips, M. Dugger
Beamline:
Arne thinks it may be possible to run the polarimeter with
only one quad at 2.4 GeV, and Volker is also looking into the
possibility. If so, this would free up a P.S. for the sweep
magnet.
Arne plans to bring a lower current P.S. into the
hall that would give 1/4 of full field in the sweep. Bernhard
thinks we should go with 1/4 field and do studies of start
counter and R1 rates versus sweep magnet excitation.
Bernhard thought we might need additional wide angle shielding
after the second collimator, about 4" of Pb. This would provide a
shadow for CLAS. A quick trip to the hall showed that we'll need
to get a support structure built. We decided to first get
some data on the background, and then if necessary quickly put
something together.
We need a helium bag for the exit line by 3/13, and Steve Christo
has been alerted.
Status of tagger electronics:
The ADML boards are ready to be returned to JLab. They will be
installed during down times for e1.
The E-counter gain matching will be finished tomorrow.
The E-counter discriminators are in house. They will be installed
next week.
Commissioning plans:
i. Tagger commissioning starting 2/10. We'll have around 4 hours
to look at the tagger and CLAS when e1 tunes the beam into the
tagger dump. Luc wants to look at signals in the tagger. Elton
wants to look at the TOF-tagger coincidence using several triggers.
DAQ and some software are required. Elton will coordinate the
planning of this test run.
ii. Start counter, tagger, trigger and DAQ commissioning. Simon, Luc
and Steve presented their plans, which require approximately 3,
4, and 2 days of beam time respectively. Writeups on their
commissioning plans will end up in the /home/tagger directory.
We need a commissioning plan for the pair spectrometer. There wasn't a
RPI representative at the meeting to discuss plans for the PS.
Prescale factors:
Reinhard presented a plan for prescaling the tagger that flattens the
hadronic rates, and this plan was endorsed by the group.
Submaster OR Prescale factor
SM1 1
SM2 2
SM3 4
SM4 8
Calibration reactions:
gamma p ->pi N. We can use Arndt's partial wave code
to get a data base of cross sections versus angle and photon
energy, and then use FASTMC, SDA, or GSIM to get acceptances.
The goal is to get cross sections nearly online and then compare
with acceptance corrected cross sections from Arndt. Several
people (Bill, Reinhard, Dave, ...) plan to work on this.
Next meeting:
We'll have a short meeting Friday Feb. 6. Time and place to be
announced.
Rory Miskimen