Minutes from target meeting held January 29 2010 in 892-2-009

These minutes are available also from:

http://wwwcompass.cern.ch/compass/detector/target/Minutes/2010/

a) Fabrice: new water flow switch for helium-3 pumps installed Friday morning. 
Complete summary of activities below.

b) Yuri: Haake water cooling unit F3 motor broken. New unit about 1600 EUR.

c) Kaori: PXI modules ok. Test DIO and ADC with multimeter and small voltage.
Software versions match. The core sweep program needs to be done. BNC-Lemo
adapters needed. Possibility to do differential or single ended measurement.

d) Norihiro: estimate polarized target figure of merit (FoM) with different
polarization relaxation times. The expected SPS planning was used, with
machine development every 13 days. Typically there is one long MD followed by
a short MD. The SMC buildup time was about 12 hours to reach more than 80 % 
polarization and for COMPASS 24 hours was used in the calculation. 
The relaxation times were 700 h for SMC case and 4000 h for COMPASS case 
at 0.6 T and 60 mK. The overall FoM was better in the COMPASS case.  
Monitoring of polarization in transverse dipole field was discussed.

Summary from Fabrice:

Dear colleagues,

I would like to summarize the ongoing work for which I am taking care
concerning the preparation of the polarized target.

- piping and welding in the pump room for the installation of new helium
pump is over. Only 2 bellows (pumping line and cavity line) have to be
inserted to close the circuits.

- cabling between the new pumps and the new control rack is ongoing. The
work should be finished by the end of next week. 

- helium-4 pumping line connected to the top of the fridge has been
removed once again this week for modification and improvement to
facilitate the next removal. It has been put back in place but the line
is still open for insertion of a below (DN100). This required an
additional helicoflex joint which has been ordered 2 days ago.

- cavity pumping line which was found cut at the storage place has been
repaired and reinstalled on its support this week (ready to be
reconnected to the outlet on fridge). 

- modification of the pipes on the Jura side is over. The quench vent
line is not positioned higher (minutes from Jaakko) but only the flange
was displaced, to facilitate circulation of visitors on the gallery. But
the position of the exhaust and recovery lines were readjusted higher.
Also the end of the quench vent line (Jura side, outside) was modified,
closed with a grid (prevention against entering birds) and a new support
was installed.

- helium distribution box with controlled valves was reinstalled on top
of the helium dewar last week and the main transfer line is reconnected.

- magnet PSUs checked and tested 20 min both (for solenoid & dipole) at
nominal current (power cables disconnected from the magnet!). Magnet
safety system checked, batteries for quench heaters also tested. Trim
coil PSUs verified, display of B1 PSU found unstable (old model) but
stability of the current is OK.

- instruments for magnet (thermometers, pressure gauges, pneumatic
valves for helium, gas heaters) found OK. A thermometer for current
leads replaced (dead in 2007).

- new display for the vacuum gauge ordered (old one disappeared).

- cap of the downstream neck of the magnet was lifted to check its
o'ring : found OK. Cap re-sealed.

- new double water circuit in the pump room was partially tested this
week for the 3He pumps (brute water not available before 12/02). The
"Eletta" water flow switch for 3He pumps seems to be dead. I ask to
replace it as soon as possible (could be this week). As soon as the
cabling will be finished for the new pumping group, I'll ask connection
to the water network (flexible pipes already prepared).

Up to know we are still in track to restart pre-cooling mid February.

Best regards,

Fabrice