Minutes from target meeting held April 1 2010 in 892-2-009

These minutes are available also from:

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

a) Fix helium-3 filling tube heater. Glue Kevlar tube end cap. Cool down 
the target cells in LN2 bath on Tuesday and load the empty cells into 
the mixing chamber. No leak to target holder vacuum detected and indium joint
seemed to be ok. All thermometers and NMR coils working. Pump out helium and
air mixture and start circulating helium-4 in the helium-3 circuit.

b) Start cooling down dilution cryostat on Wednesday morning. Thursday morning
13 K temperature in the mixing chamber reached. At the same time magnet
filled with LHe. The new helium-4 pumping group started on Thursday afternoon
and condensation of helium-4 to the mixing chamber in the evening. Around
20:30 the still (or helium-3 evaporator) full of liquid. Remove extra liquid
volume from the still and helium-4 evaporator. 

c) Rainer: the SM2 inlet cooling pipe destroyed due to too high pressure.
The circuit was closed with valves on the Jura side for pipe replacement.
Unfortunately the inlet valve was leaking a little and some water was found
on the floor. The same water is also used for the target magnet power supplies.
Temporary solution found for the Easter holidays. Fabrice: the pressure reducer
on the solenoid power supply readjusted to give a pressure about 6.5 bar. 

d) Laura: helium-4 pump oil and oil filter need to be exchanged after about
1500 hours of continuous operation for a new pump system.

e) Dilution cryostat PLC CPU failure on Friday March 26 at 18:30. Helium-3 
pumps and isolation vacuum pumps stopped. Yuri: possible to restart the PLC
manually every week.