Minutes from target meeting held April 23 2010 in 892-2-009

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2010/

a) Start 1.0 K thermal equilibrium calibration on Friday evening. The 
ethernet connection between NMR PC and PXI crate broken at the switch in
the experimental area. Use independent cable and switch without network. 
Sunday morning change broken Yale-card from coil #1 to #2. Ramp down the
magnet Monday noon and start pumping out helium-4 from mixing chamber.
Kaori: normal network connection recovered later. The switch to optical fiber 
transceiver was dead and replaced. Software watch dog to the NMR program
was discussed. Fabrice: test direct connection between NMR and magnet
PCs.

b) Tuesday morning set the dilution cryostat safety valves for closed 
circulation. Start precooling the mixing chamber from 25 K to below 3 K.
Helium-4 pumps restarted twice due to high outlet pressure. The helium-3/
helium-4 mixture condensed around 14:00. Start normal continuous helium-3 
circulation. Temperatures 50 - 60 mK reached rapidly with 5 V still heater. 
The speer up resistance bridge broken and gives interference to the other 
thermometers. At 17:00 start removing helium-3/helium-4 mixture from 
the dilution cryostat. Stop removal of helium at 23:00 and continue to 
circulate the small remaining volume of helium-4. Rest of the gas recovered 
back to tanks on Wednesday. 

c) Fabrice: pump room air conditioner maintenance on Thursday. The missing
air duct reinstalled. The measured air temperature about 17 C from the
air conditioning unit.

d) Helium-4 pump oil changed on Thursday. In addition oil filter and oil level
switch replaced. The pump oil needs to be changed about every 4500 hours
or once a year for COMPASS.

e) Helium-4 pumps restarted on Thursday noon. Evaporator filled with 
liquid helium. Start condensing helium-4 again to the mixing chamber. 
Condensation and removal of extra helium-4 completed late in the evening.

f) Target week coordination shifts were discussed. About 30 weeks to be 
covered.