Minutes from target meeting held June 14 2007 in 888

These minutes are available also from:

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

a) Target Wiki pages are now in
http://wwwcompass.cern.ch/twiki/bin/view/PolarizedTarget/WebHome

b) Jaakko was calculating the spin temperature, entropy and nuclear heat 
capacity of the proton target.

c) Fabrice: polarizations of +61.4 %, -62.4 % and +61.6 % were reached in 
26 hours. Transverse mode at 0.63 T was started on Saturday June 9 at 17:00. 
In Monday morning June 11 at 08:00 polarizations +59.9 %, -61.2 % and +60.8 %
were measured. This was followed by a field rotation test. No loss of 
polarization. Relaxation was measured in zero field with waiting times 3 min, 
12 min and 17 min. The problem with DCCT was checked again by moving it close
to RL1. Quench was observed during field rotation. On June 14 field rotation
was tried again with the DCCT in the final position and SM1 on. No problems
or extra oscillations were seen. 

d) Norihiro showed analysis of the spin relaxation time in frozen spin mode 
at 0.63 T. Downstream cell would seem to relax faster than the middle and up 
cells. Two different polarization configurations -|+|- and +|-|+ were analyzed.
At zero field in +|-|+ configuration the negative polarization relaxation time
was about 10 min and positive about 60 min. For the 6LiD about 12 - 15 min was
seen at zero Tesla.

e) Yuri: asymmetry analysis of the normalized polarized SMC proton signal gives
calibration curve to check the polarization of the COMPASS target. Correction
factors could be 1.3 - 1.7 depending on the coil and give polarizations
up to +93 %. 

f) Possible modifications to the Q-meter circuit were discussed. In the present
circuit the coil inductances are known, but the Q-value (or loss resistance), 
filling factor and cable losses need still to be determined.

g) Kaori: in transverse data taking coil #5 was used to record the proton
NMR signal. Using the Kronig-Kramers dispersion relations the phase can be 
shifted to get the absorption part of the NMR signal. The integrated areas
allow to monitor the relaxation of the polarization.