Minutes from target meeting held September 27 2013 in 892-2-009

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2013/

a) Some of the obsolete magnet cables from the target control room to target
platform were marked to be removed. Two of the racks in the control room
have magnet trim coil power supplies and these racks will not be used anymore.

b) Radiation hardness of the ruthenium oxide thermometers on the target cells
was discussed. Lakeshore has some data on this
http://www.lakeshore.com/Documents/LSTC_appendixB_l.pdf

c) Fabrice: magnet vacuum closed and leak tested to 6 10^-9 mbar l/s. After
the test the upstream and downstream flanges were re-opened and mounting of
conical horizontal screen to the downstream end was tested. The magnet is
ready for cooling down with LHe. 

Both previous protection system and power supply racks are going to be
re-used. The protection diodes and contactors are going to be placed into
latter while the first will have the power dumping resistor. The weight of
these two racks is 200 - 250 kg and 400 kg.

Work in progress on the slow control. Document on the power converters
produced. Installation platform for the racks put together in building 180
on the magnet test zone. The same platform will be used for the permanent
installation in 888. LHe recovery line ready in the test zone. The new 
isolation vacuum diffusion pump will be used, but with a more simple control
system that is installed into target control room of building 888.

d) Target loading platform modification was discussed. The top rail that is
used to support the weight of the target holder needs to be shortened.
In transverse direction the platform could be extended by 50 cm on both
sides.

e) Yuri: test CPI microwave power supply after connecting cooling water and
mains power. Problem in initial start up due to high voltage interlock in
the power supply. Finally the power supply started working normally. The
power after the power controller on the microwave table was measured to be
6 W for the old EIO tube used for the downstream end of the microwave cavity.
The new upstream EIO tube for upstream gave 8 W of power. The isolator
after the EIO tube did not warm up during the short test. Longer test is
needed for training. About factor of two in power is lost in the wave
guides going from the control room to the microwave cavity. The PLC interlock
with pt100 thermometers on the isolator needs to be reconnected. The third
microwave feed through in the dilution cryostat was closed with copper tape.
A spectrum of peaks is observed when applying microwave power into this 
multimode cavity. The peak height attenuation between the two parts of the
cavity is between 16 and 100.

New water cooler is needed to maintain good microwave frequency stability
during polarization. Presently a Haake cooler is used.  

f) Kaori: the CPI power supply was at Canada for the matching test with the
new EIO tube. Last February the company found an inverter problem which could
be fixed by resetting the control unit inside the power supply.