Minutes from target meeting held April 9 2010 in 892-2-009

These minutes are available also from:

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

a) Empty target cell thermal equilibrium calibration at 1.5 K started on 
Friday. Problem in setting magnet trim coil currents on Friday solved. 
Baratron for helium-3 vapor pressure thermometer did not work. Use piezo 
pressure gauge instead. NMR coil #1 DC offset card (Yale card) broken. 
Intermittent problems in ethernet communication between NMR PC and PXI crate. 
Switch to 1.3 K temperature on Saturday afternoon and to 1.0 K temperature 
on Sunday evening. On Tuesday morning exchange the broken Yale card to 
coil #2. Start pumping out helium from mixing chamber in evening. Stop 
helium-4 pumps and open manual bypass valves. Stop filling magnet with LHe.
About 80 K reached in the mixing chamber on Thursday morning and magnet
was also empty at this time.

b) Kaori: open Q-meter varactor power supply on Tuesday afternoon. Record the
varactor bias voltages. No problems found in this simple linear power supply. 
The units in the NMR signal files are now volts instead of millivolts.

c) Pump room warmed up to +24 C when both helium-4 and helium-3 pump groups
were running simultaneously. Fabrice: air conditioner thermostat replaced. 

d) Reconnect cables for the pt100 thermometers on target gas outlets. 
The COMPASS DCS panel for temperature monitoring needs to be recovered. 

e) Magnet trim coil G2 was discussed. Norihiro: field rotation procedure could 
be used to eliminate any trapped current.