Minutes from target meeting held June 21 2013 in 892-2-009

These minutes are available also from:

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

a) Leak test dilution cryostat safety valves and re-install the valves
into the gas system on June 5. See
http://wwwcompass.cern.ch/twiki/bin/view/PolarizedTarget/PolTargSafetyValves

b) Alcatel ASM 181 t2 failed. Open and clean up analyzer cell. Black carbon
found from around filament.

c) Leak test dilution cryostat helium-3 return volume to the diluted
helium-3/4 volume. The helium-3 outlet tube to the mixing chamber was blocked
with a soldered plug. There is a big helium leak after the needle valves.
Open the step heat exchanger shielding tube for inspection. See the
photos in
http://wwwcompass.cern.ch/elog/target_polar/191
No localized leak could be found from the heat exchangers and the heat
exchangers seem to be in good condition. Helium flow through the heat
exchangers seems to be normal. Close the heat exchanger shielding tube
and leak test for any leaks from vacuum volume. 

d) Remove aquadag graphite from the glass fiber mixing chamber with alcohol.
Close the mixing chamber into a testing tube and pump vacuum to the volume
outside of the mixing chamber. Helium leak test the mixing chamber with
the positive one atmospheric pressure difference. No leaks found. Remove
the mixing chamber from the test volume and reconnect to the step heat
exchangers/access tube. 

e) On Monday June 17 reconnect helium-3 roots cooling pipes to the tap water
lines. Test water flow. Start all the roots pumps to test the operation for a
few minutes and then stop. On Tuesday morning repeat the test with
Pfeiffer engineer to listen the bearings. The sound is normal, but some of
the motor cooling fans may have to be replaced. Unmount the last small water
cooled heat exchanger for inspection at Pfeiffer. 

f) About 200 g of used indium could be found from the cup boards.

g) Kaori: add polarization values to the runs 2011 where the NMR signals were
not recorded correctly due to Q-meter varactor bias supply problem.
See
https://svnweb.cern.ch/cern/wsvn/ptpolaris/2011/Kaori/PTpol2011updated/README

h) Fabrice: for the magnet suspension inside the vacuum vessel permaglass 
cables are going to be used. These have very small thermal conductivity.
The cable tightening system on the cold mass is going to be modified for
easier adjustment. There will be three positioning sensors on each end
of the cold mass.