Minutes from target meeting held April 14 2005 in 892-1-B09

a) Alain: small leaks being fixed in OD magnet current leads and feed throughs
for suspension cables. The magnet monitoring system upgraded. Start of LN2 
cooling expected from Monday April 18.

b) Fabrice and Yuri: no problem in trimming OD magnet with trim PSUs. Torque 
due to interaction with SM1 magnet about 30 kNm. Alain said that the field
mapping could be extended along the magnet axis to check region between OD 
magnet and SM1.

c) Yuri showed the measured RF power inside the microwave cavity as function
of frequency. The measurement was done with a 2 mm diameter coaxial cable with 
5/4 of wave length inner conductor open for coupling. The orientation of the
antenna is in vertical direction. The horizontal part of the coaxial cable of 
the antenna was fixed with a copper tape on the microwave cavity wall. 
The other end of the coax was coupled to a wave guide. The frequency was swept 
from 70 200 MHz to 70 320 MHz corresponding to the frequency range used in DNP.
During the sweep the power measured by the antenna goes from zero to a maximum 
in irregular intervals of 1 - 5 MHz. Possible explanation is coupling to 
different cavity modes or frequency dependence of microwave feeding from the 
holes on the cavity wall. 5 cm long microwave stopper was measured to attenuate
the power by 20 - 30 dB along the axis of the cavity. 

d) Communication with Tapio: the SMC cavity design and microwave feeding was 
tested by moving a dipole antenna inside the cavity. Dummy target material
with similar absorption properties like the real target material was used in
these tests.

e) Stepan was calculating modes in microwave cavity and making drawings for 
a new Kevlar tube.

f) Re-installation of the SMC magnet was discussed. 4He distribution box now
in Saclay can be installed back since it is not going to be used in the tests.
The big magnet safety valves were inspected by the CERN Safety Commission.
They would have to be reinstalled on the SMC magnet. For the moment these
valves are not used in magnet testing at Saclay. The solenoid PSU and the 
safety system would need to be re-cabled and the cables from PSU to solenoid
recovered. The cryolines for magnet and dilution cryostat would need to be
reinstalled. Part of this work has to be done anyway for the OD magnet. 
The trim coil PSUs needed at Saclay during field trimming would need to be 
recovered for the technical run at CERN.

g) After the re-installation of the target the normal start up procedure of
the target needs to be followed. Total time would be 2 - 3 months for the 
installation and technical run.