Minutes from target meeting held May 15 2015 in 892-2-009

These minutes are available also from:

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

a) Start to pump out residual helium-4 from mixing chamber on Monday morning.
The mixing chamber empty afternoon. Pump out helium-3 from vapor pressure
thermometer bulb inside the mixing chamber and close the valve at the
target holder flange. 

Change over pressure valve configuration to closed circulation mode. Start 
to condense helium-4 rich mixture from storage tanks. On Tuesday morning 
condense helium-3 rich mixture. The same mixture that was used in 2011 and 
2014 was condensed by the noon. Start all the helium-3 roots pumps.

b) On Tuesday morning test the dipole magnet operation. Afternoon ramp up 
the solenoid and start to polarize the target material with microwaves. 
At 5 o'clock on Wednesday morning magnet slow discharge due to problem
in the differential pressure level meter. 

Continue to polarize target material on Wednesday evening. Frozen spin mode
started at around 20:00. Restart polarization build up on Thursday morning
around 9:00. On Friday morning at 2 o'clock magnet slow discharge.

c) Yuri: more careful thermal equilibrium calibration is needed before 
the preliminary polarization values can be trusted. NMR system operates well.
Dilution cryostat operation seems normal. The power output from the EIO
microwave generator tubes is about two times higher than needed for the
polarization build up. No polarization loss due to hadron beam has been
observed so far. About 0.5 (50 %) polarization was achieved in about two
hours. 

The microwave isolator at the outlet of one of the EIO tubes had to be 
changed.

d) Norihiro: The power converter of the solenoid magnet was changed after 
the second slow discharge on Friday morning.

e) Kaori: internal and external NMR coils show similar behavior during
the polarization build up. The communication between PXI rack and NMR PC
was improved by removing superfluous monitoring of the PXI status.

f) Genki: calculate target cell positions from survey reports and CAD 
drawings.

g) Fabrice: automatic field rotation, solenoid/dipole start and transverse
magnetic field procedures implemented by PH-DT. These are accessible
from the magnet slow control system ICE terminal service (Industrial
Controls & Engineering) provided by EN-ICE.