Minutes from target meeting held October 6 2006 in 892-1-B09

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2006/

a) Kaori: Second TE-calibration started on Friday September 22 at 1.5 K. 
Switch to 1.0 K on Sunday midnight. Exchange broken cooling fan in roots #13
on Sunday afternoon. Continue TE-calibration at 1.0 K until Monday 16:00.
Magnet fast discharge due to blocking of the control PC. New instructions
and recovery procedure from Saclay from any field to 1.0 T. Dipole needs to
be set manually to zero field before starting the solenoid recovery.

b) Target was polarized with microwaves from Wednesday September 27 to Monday 
October 2. This was the microwave reversal of the polarization with new
polarization signs -|+|- compared to the +|-|+ before. Frozen spin mode at 
1.0 T was started with polarizations -47.1%, +54.8% and -47.0%. Polarization 
was restarted again on Wednesday October 4. The frozen spin mode in 1.0 T 
field was started in the Thursday morning 8:30 with polarizations -47.7 %, 
+54.9 %, -48.7 %. On Wednesday night 22:00 the pump room air conditioning 
was broken. The door was kept open to let cold air enter the room. On 
Thursday at 11:00 the air conditioning drive belt was replaced and normal 
operation was recovered. 

c) Yuri: EPR measurement was tried on Friday September 22 at 1 K. The magnetic
field was kept fixed and the frequency of the IMPATT microwave generator was
swept. The change in the speer resistors used as bolometers was about 1 ohm
in 1000 ohm scale. Lower temperatures are needed for better resolution. Also
the target material filling factor in the new large cavity is much smaller
than it was with the cavity used with the SMC magnet.

d) The operation of the dilution cryostat was discussed. Smaller microwave 
power than in 2004 is fed to the target cells with the new microwave cavity.
This is seen as smaller 70 mmol/s 3He flow during the polarization using still
heater voltage of 8.0 V. The polarization build up is however as fast as 
before. On Friday October 6 Norihiro reduced the amount 3He in circulation
to reach 5 - 10 mK lower temperature in mixing chamber in frozen spin mode.