Minutes from target meeting held February 20 2015 in 892-2-009

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2015/

a) Assemble new helium-3 roots WKP4000 bottom plate from Bochum together 
with internal heat exchanger on Monday. Helium leak test heat exchanger 
water cooling circuit on Friday. 

During heat exchanger leak testing it was found that the Alcatel leak 
detector does not show helium peak in rough leak testing mode while in
the fine mode leaks can be located. 

b) On Tuesday remove dilution cryostat safety valves and bring them to 
DGS/SEE/SI for inspection. The valves received back on Wednesday. Leak 
test the valves with helium leak detector. All valves in low pressure
helium-3/4 circuits were leak tight except the +0.2 bar safety valve
in the helium-4 pumping line. This valve is leaking through and will
add air pollution to the returning helium gas. See 

http://wwwcompass.cern.ch/twiki/bin/view/PolarizedTarget/PolTargSafetyValves

Install all the safety valves back to the dilution cryostat circuit. During 
this operation the helium-3 roots pump vacuum was broken and about 0.3 bar 
of air went to the mixing chamber. This air was pumped out with rotary PP4 
and roots PR4. 

c) Helium leak test helium-3 roots pumps and helium-3 gas panel in fine
mode on Friday.

d) The new "proton free" target cells with new NMR coils were received on
Monday from Bochum.

e) Produce new drawings NA58PT20150129-1, NA58PT20150204-1, NA58PT20150205-1
and NA58PT20150206-1 for target holder leveling and laser guidance support
during material loading. The Bosch Quigo cross beam laser module can be 
mounted on this system.

f) Fabrice: magnet precooling with LN2 is going on. About 110 - 120 K
reached already. Next week start to cool down magnet with cold helium gas
from the buffer dewar. Software work on the magnet going on. This includes
the field rotation procedure needed to go from the longitudinal polarization
mode to transverse mode for physics data taking. Also for the thermal 
equilibrium the field needs to be shifted by about +-10 A to see the
Q-meter baseline.

g) Norihiro: fix broken thermometer wires in the mixing chamber volume.
The wires are broken at the end of the expoxy impregnated 4-pin male 
micro-connector.