Minutes from target meeting held February 1 2008 in 892-1-B09

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2008/

a) The cables from the control room to the target platform were removed on 
Monday. All the pipes except the large helium-3 pumping line were removed 
on Wednesday. 

b) Koari calculated new TE-constants with new temperatures. Only small changes
compared to previous calculation. Also a new method by averaging the NMR-signal
with its mirror image was tried. The results are close to the previous values.
This should eliminate the possible bias due to the dispersion part of the 
NMR-signal. 

c) Yuri: free electron wave function overlaps the neighboring nuclear spins
in the hyperfine interaction. This so called contact interaction is different
from the nuclear dipole-dipole interaction in the spin Hamiltonian. Thus it is
likely to change the NMR-lineshape especially if the concentration of the
paramagnetic centers is high.

d) Jaakko: new plots on the gaussian fits to the TE-signals in elog. The empty
target cell signals are wider than the signals from ammonia. The magnetic field
map from the ammonia during TE-calibration gives a homogeneity around 80 ppm.
This field map is reproduced for the empty target cell measurements except
for coil #4, which shows 0.3 mT higher field than with ammonia inside the cell.

In time plots both integrated area and linewidth behave smoothly, but the 
center frequency has some small jumps. In the beginning of the ammonia 
TE-calibration SM1 probably induced small changes to the magnetic field 
through the shorted trim coil G2. 


Remarks from Yuri:

Dear Jaakko 
if you keep in mind the accuracy of polarization measurements +_5% then You are
absolutely right about Kaori's TE-old constants. In this case she has done 
"only small changes compared to her previous calculations " as you has 
mentioned in you weekly report. 

Unlike this statement, right now we have much better (+_2 %) accuracy used the
same data. We have also recovered the lost calibration of 9_th and 10_th coils.
This was done due to my  cross-checking method as well as the long
recalculations and filtering of bad TE and background data. Very important job
was also done by Tokuma who also helped a lot. As a result the actual special
polarisations over target length become very homogeneous as it should be in the
good operated cavity. 
Please, do not neglect by these important things for COMPASS experiment. 
 
Concerning "mirror image" we should examine her calculations ones more, because
there are still too much discrepancy between the two methods and, let me remind
you, that long before we have recommended this method for Isabell and she has
also used this useful procedure. I permanently apply this method in all
programs.    

The next remark: please, don't try to introduce me to Collaboration as a
theorist. During the Run I kept MW-system without a holiday, together with 
Kaori and Tokuma I work about TE-calibration, temperature measurements and 
elaborated the very useful cross-checking method. We jointly dismounted cables 
and microwave elements and so on.  Now I am trying to understand the situation 
with the NH3-line shape. Let me remind you that for the same calculations you 
have wasted at least half last year without any results and the certain 
conclusions, but nobody allowed the remarks to you attempts. 

Now I stop my comments to you job organization, all the best Jaakko for you. 

Regards, Yuri.