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Archived Messages for HALLA_MIN_1996@cebaf.gov: Minutes
Minutes
John LeRose (lerose@CEBAF.GOV)
Fri, 19 Apr 1996 10:00:57 -0400
Minutes of Hall A Group Meeting 16 April 1996
I. Physics Division Budget is still unresolved.
II. Coordinating Committee Meeting scheduled for 29 April
A. Two items already on the agenda
1. assigning thesis topics
2. encouraging user participation on site
B. Submit ideas and suggestions for other agenda items to
Larry.
C. Job list will be recirculated for updating this week
1. indicate jobs taken on
2. add new jobs
III. EXPINT planning to meet again. No date set.
IV. Engineering: (Bill Schneider)
A. Electron arm doors are OK.
B. Exit beam pipe to be completed today (16 April)
C. Last Friday (12 April) ran 3 magnets (Q2 Dipole Q3)
simultaneously.
D. Preparing for Beam Test: last small details on schedule
progressing nicely
E. Very unlikely, due to manpower limitations, that the
Hadron arm will be operational in June.
1. Fall back mapping plan is to map the electron arm
in June instead of the Hadron arm.
2. Will require some extra time to remove and
reinstall vacuum system.
3. Are looking at the best we to assemble the vacuum
system such that it can be easily disassembled.
V. Commissioning: (Eddy Offermann)
A. Rutgers is still not finished with the collimator box.
S. Nanda says that the toggle valve has been tested,
results unknown.
B. Multi tracking modules in the VDC package are almost
completed
1. showed results of O(e,e’p) simulation
2. resolution looks good (some subtle problems noted)
3. need to add noise effects
4. Question: What is the expected percentage of
multitracks? J.M. Finn answers: depends on the
singles rate. Expect about 40% probability that
two tracks overlap at 1 MHz.
C. Indication is that people are starting to use ESPACE.
VI. Beamline: (Arun Saha)
A. Getting ready for first beam
1. Exit beam pipe is the last item. Should be
completed tonight.
2. Quads are all powered up and cycled.
3. Beamline Test plans are in place
4. Target chamber ready. Solid targets in the ladder.
Some work remaining for remote control.
5. Start trying to get beam in the Hall at 0:00
Thursday (18 April)
B. Meeting re arc energy measurement 11:00 Tomorrow
(17 April)
VII. Chamber gas system: (Howard Fenker)
A. Making progress on assembly. Aiming to be operational
in July.
B. Will have formal review of system when we get closer to
completion.
VIII. DAQ: (Bob Michaels)
A. Have been studying accumulated data from detectors.
Problem: sometimes detectors seem to get out of sync
with each other
1. happens more often in early runs than in late runs
2. checking against Hall C experience
3. adding to on-line diagnostics to flag when it
happens
4. getting flashers operational may help in testing
5. J.M. Finn suggests that modules may not be
clearing properly
B. Fast Raster:
1. comparison made between three options for fast
raster.
a) Hall C air coil
b) Laminated Iron core C magnet: Prototype
tested. Not a significant improvement over
air core because of losses due to shorts
between laminations that could not be removed
with acid etching by the manufacturer.
c) Laminated Iron core that fully captures the
beam pipe: might be worth pursuing.
2. Suggest starting with air coil and do engineering
on last option.
3. Need latest TRANSPORT deck to determine best place
in terms of optics to put the raster magnet.
4. Will review Hall C cryotarget tests at high
currents.
IX. Magnet Measuring and Monitoring and Post-Doc search: (John
LeRose)
A. Ready to make colloidal suspension measurement of the
magnetic axis of Q2 electron on Thursday
B. Fixed NMR probes are ready for installation. Just need
somebody to crawl in and bolt the fixtures to the
mapper rails. Still waiting on vacuum feedthrough
flanges.
C. Have done polarity checks on Dipole and Q2 electron.
Keeping notes, will document.
D. Post-Doc search:
1. Last candidate on short list will be here Thursday
and Friday this week (18-19 April) to give seminar
and interview.
2. Located three letters of reference. Will
circulate.
X. Polarimeters and cryotargets: (Jian-Ping Chen)
A. Møller: no progress on the dipole.
1. Plan in place
2. very busy at Los Alamos
3. Job hasn’t been scheduled
4. Larry will see if we can apply any pressure.
B. Cryotarget:
1. assorted packages have gone out
2. working on supporting stand
C. Hall C Target:
1. have taken data at 60 and 90 microamps. No boiling
seen in 60 microamp data. 90 microamp data being
analyzed.
2. intermittent vacuum leaks have become less
frequent.
XI. Controls: (Javier Gomez)
A. Getting ready to test software on power supply
controls.
B. Beam synchronization signal is missing in BPM
C. Getting control screens up in the counting house (look
but don’t touch!)
D. Larry needs information for letter to Saclay.
XII. User report: (N. Liyanage MIT)
A. Getting VDC’s working. Now have 4 chambers up and
running.
B. Working with Bob Michaels on diagnostic software.
C. Participated in geometrical measurements of VDC
assembly. Preparing documentation.
D. Learning ESPACE.
XIII. Kevin Fissum from MIT has just arrived and is getting
settled in.
XIV. Ed Brash announces:
A. that Rutgers has hired a Post-Doc to be here this
summer and work on EPICS stuff for the FPP
B. that Gilles Quemener is working on the spin transport
through the spectrometer problem.
1. This prompted some discussion of the problem
ending with Larry suggesting we have a special
meeting just to discuss the problem.
C. that with Mark Jones he estimates that the FPP can give
a 10%(of its value) measurement of the beam
polarization in 15 minutes at 2.4GeV beam energy.
XV. Extended presentation of detector status by Bogdan
Wojtsekowski. Many plots of detector characteristics
displayed and discussed.
A. Extended discussions on:
1. How to “correctly” measure the efficiency of
Scintillators.
2. How to “correctly” measure the efficiency of
VDC’s.
B. Bogdan guarantees that tails on Drift time sum spectra
will go away when we use “good” gas. (Larry asks if
he’s willing to bet one month’s salary on it. No
response.)
-JJL