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Minutes of Hall A Group Meeting 14 October 1997
1 General Announcements: (Kees de Jager)
1.1 Kees will be out of town from 16 October =20
until 31 October. Javier Gomez will as group=20
leader in his absence.
1.2 Scheduling committee has made good progress on=20
making a schedule for the 2nd half of next=20
year.
1.2.1 Details will be posted on the web probably=20
by the weekend.
1.2.2 Hall A will have 2 major downtimes during=20
the summer.
1.3 Arc Dipole measurements originally planned for=20
January will be postponed until July.
2 Installation: (Ed Folts)
2.1 Moving into new trailers.
2.2 Ed is technician on call. (Don=92t call Mark.=20
He=92s on vacation)
3 James Proffitt reports:
3.1 Hadron Dipole power supply is up and running.
3.1.1 Precise current transducer is not working. =20
Regulating on the shunt which is not as=20
stable. With field regulation activated=20
field is still stable at better than 10-4=20
level.=20
3.2 Collimator problem was cleared up by rebooting.=20
Don=92t know what caused it.
4 Al Gavalya reports:
4.1 Joyce Miller is out for the week receiving=20
computer design training.
4.2 Susan Esp is 2 weeks from completion on the=20
radiator mount and drive. Ron Gilman should see=20
her to review status and answer questions.
4.3 Al is checking on parity detector mount. Expect=20
to sign-off this week.
4.4 Work continues on polarized 3He.
4.5 Question re S3 support frame status. Was built.=20
Pmt and scintillator mounting will require=20
additional unistrut which must be cut and=20
welded. Once that is done pmt=92s and=20
Scintillators must be mounted by hand. Frame is=20
in the Test Lab.
5 Cryotarget Commissioning: (Jian-Ping Chen)
5.1 Completed D2 boiling tests.
5.2 Got no beam for parity tests.
6 Experiment report, 91-026: (Javier Gomez)
6.1 At present things look reasonable.
6.1.1 Got first beam 2200 yesterday
6.1.2 Spectrometer checkout matches Monte Carlo=20
calculations very well.
6.1.3 Had beam problems during H2 boiling tests.
6.1.4 Accelerator having IOC problems
6.1.5 Schedule still looks good.
6.2 Kees suggests that since our transition from=20
runner nonstandard energies is dependent on=20
progress in Hall C. Javier should keep in touch=20
with Hall C.
7 M=F8ller Polarimeter and Ops manual: (Sirish Nanda)
7.1 He=92s working on analysis of FPP results.
7.2 Ops manual should be ready to go on the web=20
this week.
7.3 M=F8ller collimator did not get put in.=20
7.3.1 Will need to reschedule.
7.3.2 Sirish will try to find time to put M=F8ller=20
target in during 91-026 to establish=20
backgrounds before collimator insertion.
7.3.3 Jian-Ping points out that the TOSP for the=20
M=F8ller Dipole has expired. Sirish already=20
knows.
8 Detectors: (Bogdan Wojtsekhowski)
8.1 Re Electron Arm Gas Cerenkov:
8.1.1 Assorted ADC spectra and scatter plots=20
shown.
8.1.2 Analysis indicates getting 11=20
photoelectrons
8.1.3 Conclusion: Electron Arm gas Cerenkov is=20
ready for Physics use.
9 Jian-Ping Chen reports:
9.1 Meeting planned for Thursday afternoon to=20
discuss analysis of Cryotarget commissioning=20
data.
9.2 Meeting tomorrow (Wednesday 15 October) 1030 re=20
Compton Polarimeter.
9.3 Re Cryotarget:
9.3.1 Both targets warmed up after commissioning=20
run and cooled down again Sunday.
9.3.2 Problems noted during commissioning:
9.3.2.1 High power heater power supplies=20
failed. Power supplies have been=20
repaired and modifications made to=20
prevent future failures.
9.3.2.2 Computerized control of coolant=20
sometimes unstable. Installing non=20
computerized coolant control in the=20
counting house. Should make things=20
more reliable.
9.3.2.3 IOC crashes: working on debugging=20
software.
9.3.3 Reports on Cryotarget operation and ESR=20
capabilities:
9.3.3.1 Two modes of operation
9.3.3.1.1 Normal running: At 70=20
microamps require about 900=20
Watts of cooling power. With=20
both Halls running that goes up=20
to 1400 Watts. This is pushing=20
the limits of the ESR. Need to=20
find optimal temperature for=20
coolant coming from ESR. High=20
T=92s give higher flow rates.
9.3.3.1.2 Cooldown: Consumes almost=20
all of available cooling power.=20
For one Hall to cooldown the=20
other must be in minimum=20
consumption mode (i.e. no beam).=20
Cooldown takes 4-6 hours.
10 Meeting tomorrow (Wednesday) 0900 (A211) re cabling=20
for Compton and M=F8ller magnets.
11 Michael Kuss reports:
11.1 Gas samples taken from tanks and being sent to=20
SLAC for analysis.
11.1.1 Had problem with H2 extraction. There may=20
have been He contamination.
11.2 Working on analysis packages.
11.3 ESPACE can now put raster and BPM information=20
into histograms.
12 Meme Liang reports:
12.1 Preparing talk for Santorini. Talk will be=20
presented Wednesday, 15 October at 1500 in L207=20
CEBAF Center.
13 DAQ: (Bob Michaels)
13.1 Working on solving many small problems for the=20
run.
13.2 Re deadtime jumps: two problems found and=20
corrected. Bad cable fixed and FPP crate=20
removed from readout.
13.3 Last night (13 October) data was taken with the=20
wrong trigger file. Result is that some events=20
recorded as single were actually coincidences.=20
Data is recoverable by looking at coincidence=20
timing spectra.
13.4 John Calarco will be arriving tomorrow=20
(15 October). He=92s interested in further=20
trigger studies.
13.5 Re Helicity flipping scheme: Krishna Kumar has=20
agreed to set up a meeting of all interested=20
parties to discuss the matter. Bob will remind=20
him of his commitment.
14 Ole Hansen reports:
14.1 He=92s spent most of his first week here taking=20
care of administrative stuff.
14.2 Working on becoming familiar with ESPACE.
15 Magnet measuring and monitoring/optics: (John=20
LeRose)
15.1 Latest best numbers on distances between target=20
and collimators presented. (See ps or html=20
versions of minutes)
15.2 Still exploring possible relationship between=20
changing transfer matrix properties in the=20
Electron arm during the Oxygen experiment and a=20
possible change in dipole field index with=20
excitation as indicated by the relative values=20
of the high and low field NMR=92s
15.2.1 Good news is data taken this week=20
indicate that the ratio of low NMR to high=20
NMR has not changed significantly over the=20
past year. (i.e. the magnet is stable. )
15.2.2 Bad news is the information on the NMR=20
readings was not well recorded during the=20
Oxygen experiment. (Computer only logs one=20
of the two. You have to switch probes,=20
i.e. push 2 buttons and type in a number,=20
to get the other.)
16 Slow Controls and Alignment: (Javier Gomez)
16.1 Believe we can get spectrometer angles to +-
0.2 mr without surveying each time.
16.2 Remote movement is possible but not recommended=20
when going close to the Beamline.
17 Geraud Laveissiere reports that the micrometer on=20
the BCM that was reported broken last week has been=20
repaired. BCM has been tuned and calibrated and is=20
working fine now.
18 Installation of a =93trolley=94 (permanent lifting=20
mechanism) above the Beamline to allow easier access=20
to BCM=92s and eeP discussed. Two separate trolleys=20
may be better than one.
-JJL
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