Minutes from target meeting held August 19 2011 in 892-2-009

These minutes are available also from:

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

a) Alexander: On Wednesday 9:00 - 21:00 repolarized target from +89.2 %, 
-87.2 % and +90.0 % to +90.5 %, -91.0 % and +91.0 %. While balancing the
power between upstream and downstream cells, the remote controlled attenuator
motor decoupled. The helium-3 roots pump #1 temperature gauge showed
up to +48 C while the pt100 in different position on the same pump went up
to +38 C. The water flow indicator of one of the EIO tubes stopped though
from the transparent plastic tubes some flow could still be seen.
An alternative water flow indicator is available from aquatuning.ch 
(no. 71019). Norihiro: the reason for the stop can be also decreasing
flow due to accumulating impurities.

b) Alexander: On Thursday 17:40 the isolation vacuum reached 8.6 10^-6 mbar.
There is long trend which could indicate slow deterioration of the vacuum.

c) On Thursday evening 22:30 the general cooling water stopped in the 
experimental area. From the polarized target the diffusion pump stopped
and the still heater was automatically switched off. The still heater
was put back to operation by bypassing the PLC interlock at 23:00.
An attempt was done to restart the diffusion pump, but this failed due
to error signal from the butterfly valve. No vacuum pumping was done during
the night while the night shift was monitoring the pressure. Norihiro:
small +-0.1 bar supply pressure changes usually help to open the butterfly
valve.

d) Plot the polarized NMR-signals with both positive and negative solenoid
currents. See http://wwwcompass.cern.ch/elog/target_polar/132

e) Check possible external interference at the NMR rack position on Wednesday
afternoon with a FM receiver. France Bleu has strong signal on 106 MHz and can
be heard clearly in this position. Kaori: this kind of interference should
average to zero and should not influence the polarization measurement.