Minutes from target meeting held September 15 2005 in 892-1-B09

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2005/

a) Yuri tested microwave coupling to the existing conical cavity from the 
holes on the wave guide. All of the holes were closed with copper tape. 
Both ingoing and reflected powers were measured from the wave guide 
connecting flange in frequency range from 70 200 to 70 300 MHz. 
The holes #7 (most downstream, 7.5 mm wide) to #1 (most upstream, 1.0 mm wide) 
were opened one-by-one. When the one of the holes #4 to #7 was open the 
reflected power was the same like when all the holes are open. Opening 
of #1 to #3 did not have influence on the reflected power. Thus the microwaves 
couple to the cavity through the holes #4 to #7 only.

b) The fringe field from the new magnet at NMR-rack is about 30 mT with 1.6 m
distance from the solenoid center axis. For the SMC magnet it was 5 mT.
The reed relays in the original design of the Q-meters that allowed to 
excite coils one-by-one have been removed making the Q-meter less sensitive
to magnetic field. The balanced ring modulator SRA-1 has ferrite cored 
transformers inside. The Ultra-Physics documentation says that it should
be kept in a field less than 10 mT. The Q-meters are now inside a box made of
high permeability metallic sheet, which screens the fringe field. The forces
from the field on these sheets is to be estimated. The NMR-rack needs to be
fixed on the platform. For the best NMR-signal sensitivity short cable length
between the Q-meters and coils is preferred.

c) Jaakko leak tested the safety valves for dilution cryostat. They were also 
mounted in the dilution cryostat circuit. Summary of the leak check:

http://wwwcompass.cern.ch/compass/detector/target/Safe05leaktst

d) The dilution cryostat gas flow diagram was updated. New version is available
from Jaakko for AutoCAD CERN Mechanical 2005. The diagram was also given 
to Laura Stewart who is responsible of the helium liquefaction and liquid
nitrogen supply.