Minutes from target meeting held January 31 2014 in 892-2-009

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2014/

a) Gerhard: new one loop 10 x 50 mm NMR coils made from OD 1 mm tube with 
0.25 mm wall thickness. The two coils at ends of the target cell are going
to be mounted inside the target material. The three other coils outside of
the cell. The coils need to be rotated by 90 degrees to reduce their mutual
inductance. The NMR cables need to be installed along the helium-3 filling
tube on the bottom of the target cell. The NMR coils can not be installed
on the bottom due to the closeness of the NMR cables and helium-3 filling
tube.

Kaori: for the transverse polarization measurement the best dipole field
homogeneity is in the center of the magnet. Thus the coils inside the
target cells close to the microwave stopper should be mounted in vertical
direction.

Jaakko: update the target cell drawing with the two possible NMR coil
configurations. See http://wwwcompass.cern.ch/elog/target_polar/196

b) Remount the three rebuild water cooled heat exchangers back to the 
helium-3 roots blowers. Run the pumps without cooling water for a short 
time. The stainless steel cover plates with milled water channels have a 
small manufacturing error and were sent back to Pfeiffer.

Pump the helium-3 roots inlet with a leak detector. At level 3 10^-5 mbar l/s
no leaks observed when spraying helium on the heat exchangers below pumps
#13 and #16. Reconnect helium leak detector to the roots outlet to test
the heat exchanger below pump #20. Small helium leak observed on lateral
OD 42x5 o-ring on Saleve side.

c) Fabrice: magnet filled with about 450 l of LHe. Liquid consumption about
12 l/h and the magnet helium vessel needs to be filled every day manually
from a dewar.

The power supplies need to be re-programmed to allow controlling the current
in both directions. For the initial test it is probably easiest to change
the polarity by switching the cables. The power supply long term stability
test already done (one card burned).

d) Kaori: Lauda water cooler for the EIO tube received. Need to get a 
connection to an external water circuit. Trying to find more of the thin
coaxial cable for the NMR. Microcoax UT-034-B was used last time.

e) Yuri: calculate magnetic field from different trim coils. Try to calculate
the main coil magnetic field too.