Minutes from target meeting held August 12 2011 in 892-2-009

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2011/

a) Gerhard: On Wednesday 10:00 - 18:00 repolarize target from +89.4 %, 
-88.5 % and +91.0 % to +90.5 %, -89.7 % and +91.5 %. A field rotation
from +646 A to -646 A was started 13:45 and finished at 14:18.
The microwaves were retuned 5 - 6 MHz up for the negative solenoid
field direction. The upstream cell was polarizing quite well with
negative solenoid current, but the downstream started to show saturation.
The central cell polarization could also be improved in this configuration.

b) From time to time noise is seen in the measured NMR-signals in frequency
range 106385 - 106395 kHz. This gives wrong integrated area to the negative 
polarization values in central cell, see 
http://wwwcompass.cern.ch/elog/target_polar/129

c) Yuri: the faster negative polarization relaxation could take place due to
quadrupole interaction of protons with nitrogen-14. The target holder 
thermometers TTH4, TTH5 and TTH6 should be checked in frozen spin mode before 
and after field rotation.

d) Kaori: for the Q-meter gain calibration the Q-curves are measured with 
nominal DC gains of 1 and 200. 

e) Jaakko: simple plots now possible from the online checklist archive, see 
the links in
http://wwwcompass.cern.ch/elog/target_polar/126