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Archived Messages for HALLA_MIN_1997@cebaf.gov: Minutes
Minutes
John LeRose (lerose@CEBAF.GOV)
Thu, 05 Jun 1997 11:29:21 -0400
Minutes of Hall A Group Meeting 3 June 1997
1 General Announcements: (Kees de Jager)
1.1 Recalls last weeks efforts to get stable
simultaneous beam to all three Halls
1.1.1 First Milestone: Stable beam to all three
Halls for evaluation by the halls during
owl shift Friday morning.
1.1.2 Second Milestone: Repeat setup of stable
beam for evaluation owl shift Sunday
morning.
1.1.3 By closely following established procedure
the accelerator was successful in meeting
those milestones.
1.1.4 Main outstanding problem is 60 and 180 Hz
noise in the beam position whose amplitude
is small enough not to be a problem for
the experiments presently on the floor.
Nevertheless, Accelerator Division is
working hard to identify and eliminate the
sources of that noise.
1.1.5 Lesson for us is that we should regularly
monitor the quality of beam in the Hall.
2 Run Report: (Meme Liang)
2.1 Started at 1700 on Sunday (1 June) (845 MeV and
70 microamps CW) had 30 hours of data as of
0800 today
2.2 Completed calibration and test runs this
morning and began production on 16O at 1200
today.
2.3 Expect to take 10-12 hours of data at present
settings then move and survey Hadron
spectrometer (either late tonight or early
tomorrow if all goes well)
2.4 Showed and discussed various sample spectra
from calibrations.
2.5 Problem: We don’t have good knowledge of the
absolute beam energy. Estimates range from 1 to
2E-03.
2.6 If things continue to go as they have we could
be finished with 845 MeV by Thursday.
3 Installation:
3.1 Mark Stevens reports:
3.1.1 Hall B has been having problems with their
crane moving around on its own when
unattended (Beware of the haunted crane!)
and have instituted a policy of shutting
off the main power when the crane not in
use. We will do the same. Jack Segal says
that this has been normal procedure
anyway.
3.1.2 Bogie control modifications are ready for
installation on the Hadron Arm (will make
spectrometer movement easier). Planning to
install them while the Hadron Arm is being
measured.
3.1.3 Gary is working on the heat exchanger
3.2 Paul Brindza reports:
3.2.1 Drawings of vacuum piece between Q2’s and
dipoles has been located. Will make
modifications as follows:
3.2.1.1 Add an access port for arrangement
of magnet monitoring signal cables
3.2.1.2 Add a viewing port for verification
that cables remain in place.
3.2.2 Progress is being made on reduction of He
consumption in the Hall.
3.3 James Proffitt reports that he is working on
the spare parts issue.
4 Magnet Measuring and Monitoring and Beam Quality
checks: (John LeRose)
4.1 Oversaw the beam evaluations last Friday and
Sunday.
4.1.1 Achieved beam was small with very little
motion observed. (Thanks to Rich Holmes
and Bill Kahl of Parity for help with
position measurements) All movements were
well within allowable limits.
4.1.2 Perception is that the only thing
different was that time was taken up front
to do everything carefully and properly as
regards setting up the Accelerator
4.2 Talking with Javier Gomez about implement new
level of control that will allow the
experimenter to type in a value of the central
momentum and have all magnets set
automatically. Warns that after implementation
the experimenter will still be responsible for
seeing that the computer has done everything
correctly.
5 Cryotarget and Compton Polarimeter: (Jian-Ping Chen)
5.1 Cryotarget:
5.1.1 Lifter problem has been fixed.
5.1.2 Long (10”) bellows and 7” pipe are being
welded on.
5.1.3 Motion survey tests are going on now.
Things look pretty good.
5.1.4 Machining of upstream window is proving
difficult. Will try machining to 5 mil
thickness and etching down to 3 mil.
5.2 Compton Polarimeter:
5.2.1 Power supplies are in France but not yet
at Saclay
5.2.2 Saclay has requested BPM’s and bushings
for the assembly. We don’t have BPM’s on
hand now. Sent spool pieces instead along
with bushings.
6 Detectors: (Bogdan Wojtsekhowski)
6.1 Showed Cerenkov pulse height spectra data
6.1.1 Modified PMT bases give better spectra
6.1.1.1 Clear single and double photo
electron peaks
6.1.1.2 Still have problem with lower than
expected number of photo electrons
6.1.2 Looking into nonlinearity of
photomultiplier tubes.
7 Controls: (Javier Gomez)
7.1 Writing documentation on recent controls
changes.
8 Mike Finn introduces new student, Jason Powell.
9 Final Comments: (Kees de Jager)
9.1 No meeting next week (users group meeting)
9.2 Meetings in October, DNP and Santorini, have
abstract deadlines coming up. Spokespeople on
Oxygen experiments and Jian-Ping are urged to
submit abstracts.
9.3 Drawings: In many cases drawings of various
system parts in Hall A are not very good or
non-existent. Negligent parties can expect to
be asked to provide good drawings.
10 Late News: As the meeting was breaking up Nilange
Liyanage came in with latest results from Oxygen.
Data are looking good with missing mass resolution
of about 600 KeV.
-JJL