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Archived Messages for HALLA_MIN_1996@cebaf.gov: Minutes
Minutes
John LeRose (lerose@CEBAF.GOV)
Mon, 30 Sep 1996 09:58:30 -0400
Minutes of Hall A Group Meeting 24 September 1996
1 General Announcements:
1.1 Meeting next Monday morning (30 September) re Møller Polarimeter
installation. See Arun Saha for details.
1.2 Technical Review of Septum Magnets, Thursday 3 October, 9-12,
L207. See John LeRose for details.
1.3 Telephones:
1.3.1 Staff are reminded of lab policy re long distance personal phone
calls, you pay for it.
1.3.2 Users are informed that the lab is no longer permitted by DOE
to pay for user long distance calls to their home institutions.
Various ways of paying for such calls discussed.
1.4 PAC:
1.4.1 The laboratory is planning to hold the next meeting of the PAC
in late January.
1.4.2 There are several vacancies on the committee. Anyone with
suggestions should contact Roy Whitney, John Domingo, Betsy
Beise, or Larry Cardman.
1.4.3 Hall A users are welcome to submit new proposals but are
encouraged not to at this time. We should be devoting our
efforts to commissioning the spectrometers not dreaming up new
experiments.
1.5 Beam Schedule: New schedule (different from what previously appeared
on www) for end of 96 and 97 due out tomorrow (25 September). Will
be reviewed in public meeting on Monday 30 September.
1.6 Volunteer needed to work on ozone control/dissipation in end stations.
Arun Saha accepts the job.
2 Engineering: (Bill Schneider)
2.1 Electron-arm now at 45 degrees. Pointing is now correct within 0.5 mm.
Roll of dipole correct to within 0.5 mm. Vertical position correct to
within 2 mm and is being corrected.
2.2 Hadron-arm:
2.2.1 Magnets are full except for Q1
2.2.2 Checking out dipole.
2.2.2.1 getting help from Dynapower
2.2.2.2 quench protection circuit tested
2.2.3 Quadrupoles are ready to be tested
2.3 Water Fall target to be installed during the week before 12 October
2.4 Horizontal and Vertical Positioning Systems (HPS, VPS):
2.4.1 long discussion of work to be done and when
2.4.2 Can J. Proffitt use software help? He’d prefer to do it himself. If
someone else took over they would have to take over the whole
system not just VPS, and HPS.
2.4.3 How long does it (and will it) take to change angles? Bill says 2-
3 maybe 4 days now, 1 day maybe 1 shift in the December -April
timeframe when we have more experience. This time we got
lucky, the spectrometer didn’t require much realignment after
moving.
3 Electronics: (Jack Segal)
3.1 Flammable gas is now flowing in the detector tent.
3.2 Jack requests that people be careful when working around or having
work done around detector stacks. Protect the detectors and their
cabling from exposure to dust and debris. Know or find out what’s
fragile. Check the setup before work is actually done.
4 Chamber Gas: (Howard Fenker)
4.1 System is up and running. Don’t ignore alarms!
4.2 Reviewed gas supply system and interlocks.
4.3 Explained procedure for bringing back on-line after replacing an empty
bottle. (low pressure override and resetting excess flow valve)
5 Beamline: (Arun Saha)
5.1 Installing slanted target tomorrow (25 September)
5.2 Beam current measurements over the weekend were calibrated against
the Faraday cup. Report on results next week.
5.3 Run Summary sheets are available on the www.
(http://www.cebaf.gov/halla/beamline/beamline.html)
6 Møller Polarimeter and Ops Manual: (Sirish Nanda)
6.1 Møller and Compton dipole magnet power supplies ordered. Bids are
due this Thursday (26 September)
6.2 Møller installation schedule reviewed. Will be discussed at meeting on
Monday (see above)
6.3 Ops Manual: Have received two more contributions. There are still a lot
of holdouts.
7 Commissioning: (Eddy Offermann)
7.1 Last weekend finished elastic peak scan with and without sieve at 845
MeV/c, y0=0. at 16 degrees.
7.2 Plan to do extended target studies next (i.e. systematically vary y0).
7.2.1 PROBLEM: Previous count rate estimates were off by a factor
of 1000. Can’t do sieve slit measurements at 45 degrees on 12C
at 845 MeV/c.
7.2.1.1 30 degrees not immediately possible because of window
limitations on scattering chamber. Bill will look into this.
7.2.1.2 Considering alternate targets.
7.2.1.3 Thicker sieve to allow angle reconstruction studies in QE
region not practical.
7.2.2 PLAN: Will do extended target studies with full solid angle this
weekend and extended target studies with sieve the following
weekend at a more forward angle.
7.3 Discussion of migration to the common UNIX environment, problems
and advantages.
7.4 Recommend that people do their data analysis in their own directories
8 Detectors: (Bogdan Wojtsekhowski)
8.1 Preliminary results from gas Cerenkov using CO2 shown. Number of
photelectrons goes from 4 with air to 10 with CO2
8.2 FPP status: (Mark Jones)
8.2.1 Cosmic ray studies underway.
8.2.2 10 dead wires out of 2000
8.2.3 Showed estimate of efficiency vs. HV.
8.2.4 Gas Leaks: 150 cc/min in gives 100 cc/min out. With 2000
straws there’s a lot of plumbing.
8.2.5 Carbon analyzer almost completed mechanically
8.2.6 4 of 9 S3 panels mounted
8.2.7 Chamber 4 ready to be shipped from Rutgers
8.2.8 Ron Gilman starts one year sabbatical at TJNAF tomorrow
(25 September)
8.3 Help needed on shower counter analysis software!
8.4 Bogdan asks for constructive feedback on poster display for DNP
meeting.
9 Magnet Measuring and Monitoring: (John LeRose)
9.1 Still working on dipole field maps. Preliminary indications are that the
dipole magnet is very close to what it was designed to be.
9.2 Calculations of optical properties of the Spectrometer based on current
settings used in the quadrupoles and the measured quadrupole strengths
are in substantial agreement with the measured properties. Previous
disagreements were mostly the result of clerical errors leading to
comparing measured optical properties to calculated optical properties
for different magnet settings.
10 DAQ: (Bob Michaels)
10.1 Analyzing results of trigger tests last weekend
10.1.1 Pedestal suppression worked fine
10.1.2 Had problems with buffering
11 Controls: (Javier Gomez)
11.1 Wrote EPICS code for carbon blocks (FPP)
11.2 Working on debugging GPIB handler with Yves Roblin
11.3 Looking into parts for alignment system.
12 Cryotarget: (Jian-Ping Chen)
12.1 Meeting next Friday at 1400 to discuss scheduling.
12.2 Design: Platform layout and gas panel started.
12.3 Techs: leak checking heat exchangers
12.4 Students and Postdocs working on:
12.4.1 EPICS alarm builder installation
12.4.2 Digital I/O and lifting mechanism control
12.4.3 Wiring cryocan to target loop
12.4.4 Breakout box for temperature monitoring and control
12.4.5 Solenoid valve control elctronics design completed
12.4.6 Assembling parts and electronics for J-T valves
12.4.7 Frequency controller for motor
12.5 Pressure transducer stability test results look good.
-JJL