Minutes from target meeting held June 17 2011 in 892-1-B09

These minutes are available also from:

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

a) Most of the magnet thermometers stopped working on Sunday morning 5:30.
The problem solved on Tuesday by switching CABTF1 inside the magnet cryogenics
rack off and on again. Fabrice: thermometer failure could cause the current
lead heaters to switch on permanently. Possibilities to detect this failure
are being discussed.

b) Condense helium-3/4 mixture on Tuesday. Restart dilution cryostat on 
Tuesday evening. On Wednesday when still heater switched on large pressure 
difference between PV8 (still) and P1 (roots inlet). Probable blockage in 
the internal heat exchangers due to the liquid nitrogen from target loading. 
Set still heater to 8 V and start to polarize the central cell. About -40 % 
reached in two hours. Set still heater to 12 V and polarize upstream and 
downstream cells only. About -30 % reached in two hours. See
http://wwwcompass.cern.ch/elog/target_polar/114

c) Stop polarizing at 14:00 and start putting helium-3/4 mixture back to
storage tanks. The dilution cryostat empty 21:20. Stop helium-4 evaporator
pumps and pressurize the evaporator to atmospheric pressure. The evaporator
empty at around 1:00. Mixing chamber warmed up to 41 K by Thursday morning 
8:00. The evaporator warmed to 32 K. Analyze circulating residual gas: 
7.5 % helium-3, 78.5 % helium-4 and 14 % of nitrogen. Pump the residual gas 
to tank #9 and fill in helium-4 from bottle. Circulate the gas a few hours 
and pump out. This repeated a few times. Analyze clean helium-4 sample
21:00. Restart cooling down of the mixing chamber from 58 K and evaporator
from 51 K. Friday morning 8:00 evaporator at 10 K and mixing chamber at 53 K.
Increase helium flow to mixing chamber to cool down faster.

d) Target shift instructions 2011 in wiki
http://wwwcompass.cern.ch/twiki/bin/view/PolarizedTarget/PolTargShift

In addition to target week coordinator a target on call person can help in 
more difficult tasks. 

e) Fabrice: helium-3 roots water drain fixed with pasta. During rain some
of the water has leaked out from this connection.

f) Norihiro: to use Step 7 for PLC PVSS was installed to PC since it includes
the license for Step 7.