Minutes from target meeting held June 23 2011 in 864-2-B29 These minutes are available also from: http://wwwcompass.cern.ch/compass/detector/target/Minutes/2011/ a) Start helium-4 evaporator pumps on Friday afternoon. Condense helium-3/4 mixture and last tank filled in by Friday evening. Ramp up the magnet Saturday morning 10:00. Start to polarize central cell to negative polarization. Average cell polarization of -80 % reached by 20:00. The microwaves stopped Sunday morning 2:00 due to PLC interlock. Continue to polarize from Sunday morning 8:00. -90 % reached by 17:00. Go to frozen spin mode. See http://wwwcompass.cern.ch/elog/target_polar/115 b) Yuri: start to polarize up- and downstream cells to positive polarization from Monday 9:00. +84 % reached for upstream and +82 % for downstream. Start frozen spin mode 21:30. Restart polarization Tuesday 10:00. +89 % and +87 % reached. Frozen spin mode from 17:00. c) On Tuesday morning 3:00 Q-meter varactor power supply stopped working. Attempt to recover by switching off and on several times in the morning. Open the NMR rack and remove the power supply from the rack. Check the voltages for different channels. Reinstall the power supply to the NMR rack and normal NMR signals are recovered. See http://wwwcompass.cern.ch/twiki/bin/view/PolarizedTarget/PolTargVariCap d) On Wednesday 12:00 go from 2.5 T to 1 T to reduce helium consumption. The dilution cryostat consumption reduced to about 20 l/h while the magnet consumes about 30 l/h giving total of about 50 l/h. The helium liquefier stopped for a few hours and the purifier warmed up for cleaning. e) Jaakko: AVS1 resistance bridge range needs to be set to "6" in frozen spin mode. Otherwise incorrect temperature is shown. f) On Thursday 9:00 back to 2.5 T to measure the polarization. Switch on the microwaves and increase the polarizations to +86.9, -84.0 % and +86.8 %. Start frozen spin mode from 13:15. g) Werner: the visible color centers in the new ammonia are the probable reason faster polarization build up. It would be interesting to compare polarization relaxation to the old ammonia in transverse 0.63 T field.