Minutes from target meeting held January 14 2011 in 926-1-039

These minutes are available also from:

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

a) Replacement of the broken self pressurizing (+0.5 bar) 200 l LN2 dewar 
was discussed. First offer from Wessington cryogenics about 10 kCHF. The dewar 
size may not be compatible with the access door to the experimental zone. 
The other possibility XRP200 from Cryodiffusion with rolls, transfer line
and pressurizing system. This model could be refilled by opening the neck
while the Wessington dewar has a separate fill port. Jaakko: renting or
borrowing a dewar for the target material loading could be an option. For 
the target material storage dewar refilling one LN2 transport dewar should 
be enough.

b) The cooling water valves to the helium-3 roots blowers and helium-4 pumps
were closed on December 6. One week later on Monday December 13 three of the
water flow spinners with a glass window were found to have exploded. The 
pump room temperature was +3 C in the morning of December 13. The maximum 
pressure for these spinners is 7 bar.

c) Leak test the helium-3 roots by connecting the leak detector to the roots
outlet. Open the electro-pneumatic valve VHB. Let helium gas into the cooling 
water circuit. No leak detected. Repeat the test by pumping from the roots
inlet side. Start the roots for a few minutes without cooling water and pump
the outlet with a leak detector. No leak from the cooling water circuit 
detected.

d) Three spare water flow spinners found from the stock (Romford Rhodes).

e) Moving of the polarized target platform 220 cm upstream for the Drell-Yan
physics was discussed. This work is similar to the work done in 1999-2000
when the polarized target was installed into the present position. Main 
conflicting part is the loading platform and the hodoscopes. The concrete
blocks may need to be removed where the last beam line magnet is. Also the 
access to the zone needs to be discussed. One option is to move the door 
PPE221 with its shielding blocks. The target holder length is about 2.5 m.
Thus re-assembling the dilution cryostat into the magnet needs at least
3 m of free space upstream of the superconducting magnet. 

f) Yuri: the microwave table could stay in the present position if more
bends are added to the waveguides.

g) Fabrice: new diffusion pump ordered in December. The control system will
not be ready for run 2011. Support from CERN available in case of problems
with the Alcatel diffusion pump system now in use.

h) Jaakko: remove baratron pressure gauge from the helium-3 vapor pressure
rack. Test the electronics unit in office. A flat cable from the main PCB
to a connector PCB was found to be disconnected inside the box. Reconnect the
cable and the baratron starts to respond to pressure changes.