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Archived Messages for HALLA_MIN_1997@cebaf.gov: Minutes
Minutes
John LeRose (lerose@CEBAF.GOV)
Fri, 30 May 1997 14:11:33 -0400
Minutes of Hall A Group Meeting 27 May 1997
1 General Announcements: (Kees de Jager)
1.1 In light of last week’s attempts to deliver simultaneous beams to three
halls, Larry Cardman has prevailed upon the Accelerator Division to
make a major effort to improve beam availability with the final goal of
being able to deliver reliable simultaneous beam to three halls.
Meetings are ongoing and decisions are pending as to how this will be
achieved. Possible immediate implications for us:
1.1.1 Some loss of facility development time (e.g. the upcoming PID
run) to Accelerator operations development work.
1.1.1.1 Hall to be closed late this afternoon anyway
1.1.1.2 Withdraw target to blank position.
1.1.1.3 Hold off on spectrometer moves. Will have to move
back where we are for Oxygen.
1.1.2 Small (2-3 day) blocks of time during the next few weeks to
one month being dedicated to machine development.
1.1.3 Cryotarget installation starts 11 August anyway. If oxygen is
not finished they can come back later.
1.2 Measurements of the distance from the target to the collimator box
indicate that the collimator is about 6 inches closer to the target than
previously thought.
1.2.1 Want all parties to agree on the distance.
1.2.2 Need to measure the Hadron arm
1.2.3 Need to measure and record all distances along the
spectrometer
1.2.4 Need written report of all measurements
1.2.5 Ultimately want a consistent set of data on all locations and
apertures in the spectrometers.
1.3 Re secretaries: Our secretary is Rachel Harris. Please bring all
secretarial work to Rachel unless she tells you to do otherwise.
2 Run Report: (Meihua “Meme” Liang)
2.1 Reviewed achievements:
2.1.1 H2O Target thickness measurements.
2.1.2 Magnet reproducibility tests (2E-04 shift in elastic peak
position, don’t know whether the shift comes from the beam or
the spectrometer or both)
2.1.3 White spectrum studies
2.2 Problems encountered:
2.2.1 Poor beam quality and availability
2.2.1.1 60 Hz noise
2.2.1.2 Positional instabilities (Bill Kahl volunteers to compare
with data collected by parity)
2.2.2 Beam dump radiation level trips (trip levels have been raised)
2.2.3 NMR cable in trajectory path on Hadron arm. (has been
corrected)
2.2.4 NMR communications problem.
2.2.5 Protective plastic window not removed from scattering
chamber (has been added to the checklist)
2.2.6 Hall A operational problems:
2.2.6.1 Inadequate logbook keeping
2.2.6.2 Failure to fill out checklists
2.2.6.3 Failure to inform run coordinator immediately if there is
a problem.
2.3 Discussion of absolute energy calibration problem for 16O experiment.
3 Installation and Engineering:
3.1 Ed Folts reports:
3.1.1 Moving various items in and out of the Hall.
3.1.2 Will start tomorrow (28 May) on:
3.1.2.1 Møller target cooler
3.1.2.2 Raster bench
3.1.3 Working on waterfall target water interlock.
3.2 James Proffitt reports:
3.2.1 Javier is working on NMR communications problem
3.2.2 James requests that he be given a list of anticipated magnet
settings before each run. (Needed to set flow rates correctly
and set software limits)
3.2.3 Lead flow problem for Q3’s discussed.
3.3 Paul Brindza reports:
3.3.1 Working on solid target extension for the Cryotarget
3.3.2 Starting on Møller target cooler assembly. (All parts are ready)
3.3.3 Stand modification for Dick Lindgren is done.
3.3.4 Septum magnets are out for bid. Due back 1 July
3.3.5 Working (in consultation with John LeRose) on modification
to vacuum tank between Q2’s and the dipoles to allow better
control and management of field monitoring cabling.
3.3.6 Cryogenics is looking into automatic control of He pressure in
magnets
3.3.7 Trying to find ways to reduce and stabilize He usage in the
Hall. We use more He when the magnets are off than when
they are on! Trying increasing standby flow rates.
4 Møller Polarimeter: (Sirish Nanda)
4.1 Completed 5 minute test of target with 2 microamps of beam last
weekend. Uncooled target showed no observable damage, as
expected.
4.2 Reviewed commissioning plan. Expect to be ready foe 20 microamp
operation in early July.
4.3 Dan Dale is installing last plane of detectors. Dan reports that all is
going reasonably well. He’s now debugging electronics.
4.4 Howard Fenker reports on further studies with the auxiliary wire
chambers. Now have improved statistics over last week. Things still
look OK.
5 Detectors: (Bogdan Wojtsekhowski)
5.1 Detectors ran well last weekend. (e.g. No VDC trips )
5.2 Problem with reset boards conveyed to Jack Segal.
5.3 Wondering about long tails in shower spectra suggesting very high
energy particles. Will be discussed at data analysis meeting Thursday
(29 May)
5.4 Reviewed plans for facility development run.
5.5 Discussion re Aerogels:
5.5.1 Aerogel will be removed at the start of the FPP run.
5.5.2 It’s up to 1st Oxygen experiment to decide if they want to
leave it in or remove it before FPP runs.
6 Cryotarget and Polarized 3He: (Jian-Ping Chen)
6.1 Polarized 3He:
6.1.1 Collaboration meeting last Friday and Saturday (23-24 May)
6.1.2 In June Wolfgang Korsch and Emlyn Hughes will be at JLab to
work on design issues with Paul Brindza, Al Gavalya, and Jian-
Ping.
6.1.3 Expect to have final design ready by the next meeting in late
July.
6.2 Cryotarget:
6.2.1 Cryocan and target assembly have been moved back to the
assembly platform.
6.2.2 Dimitri Margaziotis and Jian-Ping had some discussions with
Mike Seely last week re the high power He target. Problems
defined included:
6.2.2.1 getting adequate cooling power
6.2.2.2 Acquisition of 3He is becoming problematic
6.2.3 Ed Folts asks to see installation plan in order to better
coordinate manpower
7 UPDATE 5/28:
8 From the Benesch report of the 8:00 5/28 accelerator meeting:
9 The next four shifts will be devoted to optics work to the BSY, all passes.
The halls will lock up on swing shift tomorrow (Thursday) and the optics will
then be cleaned up to each hall. Owl shift Friday is to be devoted to relatively
steady running to three halls while beam quality checks are made, with optics
iterations as required.
10 Follow-up from 13:30 meeting in MCC: Accelerator will work until owl
shift Friday to clean up the beam at which time each of the three halls will
perform whatever they consider to be valid tests of the beam quality and
report back to the Accelerator. There will be a meeting Friday at 13:00 to
review the results of the tests. Accelerator will then spend the rest of Friday
and Saturday until swing shift taking remedial action. Swing shift Saturday the
Halls will again evaluate the beam quality after which if all goes well beam will
be returned to the experiments.
-JJL