Minutes from target meeting held June 21 2007 in 892-1-B09

These minutes are available also from:

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

a) Target Elog is now in http://wwwcompass.cern.ch/elog/target_polar/ .

b) Polarizing of the target was started on Saturday morning 08:00. On Monday 
frozen spin mode was started at 17:00 with polarizations -62.92 %, +62.03 % 
and -65.88 %. For middle cell ten times smaller power than before was used. 
On Tuesday 23:00 longitudinal mode was started for the alignment run. 
The transverse data taking was resumed on Wednesday morning 3:00. 

c) Yuri: the NMR signal asymmetry depends on the sign of the polarization.
Possible reason Q-meter nonlinearity. 

d) Jaakko: in the 6LiD target NMR coils embedded into the target material had 
1.5 - 1.6 times higher second moment compared to the coils mounted on the 
target cells. This can make comparison of the SMC embedded coils signals 
difficult with the COMPASS NMR coils on the target cells.

e) Kaori explained the tuning procedure for the Q-meter. First the cable 
length is checked with an oscilloscope and pulser. Then the tuning capacitor
is adjusted to get symmetric Q-curve. Finally the phase cable for the ring
modulator is adjusted using the diode output from the Q-meter. Jaakko: further
phase correction can be done in a computer with  Kronig-Kramers dispersion 
relations (for example with -p option in plotsig).

f) Norihiro showed analysis of the polarization relaxation from June 6 at 
0.63 T. Coil #5 showed relaxation time of 10 000 h and coil #6 6500 h. 
From the measured NMR-signal dipole field map was produced. 

g) Ishimoto: new carbon fiber epoxy vacuum chamber in preparation for the 
hadron target.