Minutes from target meeting held April 15 2011 in 892-1-B09

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2011/

a) Nine Ziehl PTC-resistor relays MSR220K were replaced with new ones in 
the helium-3 roots control cabinet April 4 - 6.

b) On Monday April 4 test first helium-3 roots pump water cooled heat 
exchanger at 7.15 bar.

c) Start target isolation vacuum pumps. The fuse inside the control
box with PLC was replaced twice before stable operation could be started.
Open cooling water and test diffusion pump. Stop pumping with diffusion
pump and connect isolation vacuum to helium leak detector. Spray helium
on the vacuum o-rings. No leaks found. Connect gas helium line to the
separator and let helium flow through the screen cooling lines and cavity
pumping line. Open the needle valves to the helium-4 evaporator. No leak 
to isolation vacuum seen.

d) Problem with target platform power. Knocking on the AUL box switched off
all the power. Technical service called to fix the cables inside the AUL 
distribution box.

e) Spare flow spinners for helium-3 roots blowers received from Apollo Flow.

f) On Monday April 11 one of the small heat exchangers received as completely
water tight and tested. Connect the vacuum volume of the heat exchanger 
to helium leak detector. Good vacuum reached with low background leak level.
A helium leak located to one of the pipe feed throughs with hard soldering.
The heat exchanger returned to main workshop for repair.

g) On Tuesday April 12 unmount the last heat exchanger from the pump system.
Water leak found also from this unit. Thursday afternoon visit CERN central
workshop. The possibility to glue the water leaks with Ecobond was discussed.
Friday meeting with TE/CRG Johan Bremer to discuss on the heat exchanger 
repair.

h) The roots cooling water inlet pressure was increased with the new water 
circuit for the run 2010 from 3.3 bar to 5.0 bar. In addition the flow
control valve was moved from the inlet to outlet. See 
http://wwwcompass.cern.ch/elog/target_polar/111

i) Two spare heat exchangers were helium leak tested on Friday.

j) Norihiro: order new PLC modules for analog input voltage and current and
for temperature. Make longer test on the diffusion pump. The stable outlet
water temperature around +38 C. Change new power supply to the PC used 
to program the PLC.

k) Hiroki: install new motor to the microwave attenuator.