Minutes from target meeting held October 7 2010 in 892-2-009 These minutes are available also from: http://wwwcompass.cern.ch/compass/detector/target/Minutes/2010/ a) Wednesday 16:45 back to longitudinal field 2.5 T with polarizations -76.7 %, +76.0 % and -74.1 %. Go to transverse dipole field 0.63 T and ramp down the magnet to zero field. The speer resistors on the target cells monitored for release of energy stored in the spin system. Finally solenoid back to zero field at 18:11. To remove polarization use still heater 4 V, but with all the helium-3 roots running. Zero field during the alignment run. Polarization build up started at 21:20. Friday morning polarizations +79.3 %, -76.9 % and +79.4 % reached. Start transverse mode in 0.63 T dipole field 9:14. b) During the polarization build up oscillations observed in the helium-4 recovery line pressure with period of about 50 minutes. Probably due to automatic switching between the helium balloon and purifier at the helium liquefier. These caused also fluctuations in the magnet current lead flow. Back in the transverse mode with microwaves off these oscillations disappeared. c) Jaakko: compare polarization loss rates in frozen spin mode between 2007 and 2010 for the ammonia target. In 2007 both solenoid 1 T and dipole 0.63 T were used while in 2010 only 0.63 T dipole is used. The median loss rates were in 2007 (including 1 T data) 0.39 %/d, 0.43 %/d and 0.64 %/d while in 2010 so far 0.32 %/d, 0.40 %/d and 0.44 %/d (up, middle and down). These numbers have a large error. See http://wwwcompass.cern.ch/elog/target_polar/97 d) Miroslav reported on the Spin 2010 held at Julich. e) Yuri: while sweeping down the dipole magnetic field to zero, the positive and negative polarizations seem to release their energy the same way. The proton relaxation could be mediated by the nitrogen-14 nucleus, which is observed as polarization increase in the nitrogen. This is difficult to observe however since the nitrogen-14 has a broad NMR line due to the quadrupole moment.