Minutes from target meeting held June 1 2007 in 892-1-B09

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2007/

a) Fabrice: dipole field direction was checked with muon beam. The beam 
deviates to wrong direction and the dipole field must point up. On May 31 
the dipole power cables were exchanged to correct the field direction for 
transverse physics data taking. After this the -646 A solenoid was ramped 
to 0.63 T dipole. During this operation magnet fast discharge due to over 
current reading happened. The magnet was refilled with liquid helium in
6 hours. This was followed by field rotation test in deuteron mode
with 346 A, 546 A and 646 A. The 646 A test was done both with trim coil
circuit breakers open and closed. On June 1 the ramp in proton mode +646 A 
solenoid to 0.63 T dipole was done and magnet fast discharge took place.
After refilling the magnet with liquid helium the buffer dewar level was
already low 24 %. The nominal helium level in the buffer dewar was reached
May 2 at 5:00. The Danfysik current transducer position was changed so that
the relay RL12 should not induce currents to it any more. Yuri: Danfysik
power supply could be tested alone without the magnet

For more info on the Danfysik System 854 S power supply and Ultrastab 2000 
current transducer see http://www.danfysik.com/02custom_designed.htm
and http://www.danfysik.com/02rack_type.htm .

b) After the center cell reached the maximum polarization -66 % on May 25
polarizing up and down stream cells was started. On May 27 +65 % up 
and +71 % down stream polarizations were reached and polarization of the
center cell was restarted. On May 29 +66 %, -64 %, +69 % were reached
and frozen spin mode was started.

c) Yuri: HP power meter needs professional service at Agilent. The microwave 
leakage in the downstream stopper is probably in the target holder. Upstream
microwave stopper is ok. Next polarization should be done -|+|- to understand
better the NH3 properties. Bochum could measure NMR signals at different
polarization values to compare with the signals of COMPASS target.

d) Takuma: NMR rack temperature raised a few degrees during the hot weather 
conditions. The use of demineralized cooling water in the secondary circuit
was discussed.

e) Fabrice: problem with dilution cryostat Oracle database connection. Reason
probably the NMR PC that does not close sessions after accessing the database.
The dilution cryostat PC has a small Virtual Instrument application to send 
the magnet currents to the run log book MySQL database and to NMR PC.