Minutes from target meeting held August 7 2015 in 892-2-009

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2015/

a) On Monday noon rotate dipole field to solenoid and measure target 
polarization during beam stop. On Tuesday switch on the microwave generators 
to top up the target polarization during work on SM2 cooling water.

b) On Wednesday morning ramp up the solenoid field and start to top up
the polarization. The microwaves stopped at midnight. During field rotation
from solenoid to dipole the dipole current started to go down from 472 A.
Ramp up the solenoid manually when dipole current was below 373 A.
The solenoid current stopped at -400 A while the nominal 2.5 T field
is reached at -647 A. Rotate field back to dipole 0.63 T with nominal
current of +588 A for physics data taking.

On Thursday morning rotate from transverse field to longitudinal and
measure polarization.

c) On Friday rotate field to solenoid to measure polarization during no beam
time.

d) Calculate median NMR peak frequency shift for a typical polarization 
build up for external coils 2011 and 2015. The polarization of run 2015
is based on preliminary thermal equilibrium signal analysis without
measurement of background proton signal. Comparing the slopes 2015 and
2011: 0.3528 kHz/% / 0.2982 kHz/% = 1.183. See 
svnweb.cern.ch/cern/wsvn/ptpolaris/2015/fshiftpol/fshiftpol15.txt

e) Fit SMC three gaussian function NIMA 419 60 to the measured polarized 
NMR signals. In 2011 similar fit was done and the polarization values from
the fit had to be corrected by a median factor of 0.9223 to get measured
values from the thermal equilibrium calibration. Using this factor and
fit value for 2015 signals the mean correction factor for external coils
is 1.182.

The two results indicate that below the measured thermal equilibrium NMR signal
there is about 18 % of protons from different target holder construction 
materials.