Minutes from target meeting held on 26th of September 2002 in 892-1-B09

a) Due to overheating of roots pump #4 up 80 C as measured from side, 
the polarisation build up with EPR-line taking was interrupted on Thursday.
The plan is to do the measurement during the first polarisation build up
of 2003. Jaakko said that 4He operation would still be possible and that
the broken pump #7 could be bypassed by opening the overpressure valve 
in parallel.

b) No modifications to the target are planned for 2003 since there is no
explicit requirement from collaboration. Thus we need only to fix the
NMR problem. Yuri wanted to have one coil inside target material in each
target cell. Jaakko said that we had already 2 coils inside this year, but
one of them was shorted.

c) Kaori estimated that with the new TE-calibration about 1 month is needed
to analyse the NMR signals to determine the polarisation. The data presented
in the COMPASS workshop was the online data for 2002.

d) Unloading of target material in planned on Monday 7th October. Weighting
of material is to be done after unloading separately for upstream and 
downstream cells. Liquid argon will be delivered on Thursday 3rd October. 
The detectors and concrete blocks upstream of target are removed on 
Tuesday 1st of October. During the slow warm up only little LHe is needed
to cool down the screens and separator line. The LHe transfer to magnet
was stopped on Monday 30th of September. There might be ice blocking
the target holder so we should be prepared to force the target holder out.

e) Status of microwaves: 2 EIO tubes "CERN" with old PSUs (FM), EIO tube 
"Nagoya" with new PSU (no FM). Inquiry to Varian resulted offer with no 
FM possibility. Stefan found 1 W IMPATT/GUNN diode with 500 MHz mechanical 
tuning and 100 MHz electrical tuning, and FM with 100 - X00 Hz possible. 
Stefan estimated that with this power level it is possible to install 
the semiconductor microwave source to the control room. Jaakko said that
for fast microwave polarisation reversal high power is needed. 
The polarisation build up time with the new system should be tested.
Yuri said that polarisation can be started with the EIOs, but a microwave 
switch is needed to switch from EIOs to IMPATT/GUNNs. Bochum will buy
2 new IMPATT/GUNNs 27kEuro/piece. Werner said that for proton polarisation
in 2006 we may need more tuning width. Yuri asked about possibility to
modify of new Nagoya PSU in Bochum workshop to allow FM.

f) The problems in the dilution cryostat pump system was discussed. Jaakko
asked who pays repair work for the 3He pump system. Norihiro commented that
there are quite many problems with this system and it is probable that these
will continue 2003. Jaakko said that complete overhaul at Pfeiffer was done 
before the installation to pump room. Jean-Michel organised M. Delacharlonny 
from Pfeiffer to check the problem on site. Gunter said that last year 
Pfeiffer requested that the broken pump is send there for service since there
are no spare parts available for this old system. Jaakko said that he will 
change oil,  purge zeolith filters and remove cooling water before winter 
shutdown. 

The possibility to buy new roots pump system was discussed. Werner asked what
would be price of a completely new roots pump system. Jaakko said that the 
pump system was specially designed for pumping 3He of dilution cryostat with
certain flow rate and new specifications should be written down carefully. 
Jaakko asked if there is significant progress in roots pumping technology, 
which could motivate such an investment. Stefan suggested manual bypass 
valves for all the pumps. Yuri said that in SMC there was a big cooling fan 
that could be used to cool the motors, if one of the cooling fans is broken.
Jaakko said that the cooling fans are easy to exchange and this has already
been done. Jaakko said that we should buy spare cooling fans and possibly 
spare motors. Some spare material is already available in pump room.


g) The oxygen impurity problem assumed to come from evaporation pumps was
discussed. Norihiro said leak could be from roots pump since the purge
rate of LHe liquefier slowed down by factor 2 after we reduced the consumption
of LHe by switching off the roots and pumping only with rotary. Jaakko said
that if the the relative contamination level stays the same, then this is 
expected to happen and it does not show that there is leak in the root pump.
After warming up we will check the leaks by ourselves. If there is money
available, the 4He pumps can be send to service at Alcatel or external
company can be payed for leak testing. The quality of piping could also 
be improved. This could include missing solid piping between pump room and
concrete wall for the cavity. Also connecting tubes to cavity and horizontal
screen at cryostat should be better mechanically supported. The standard
service for the pumps is to change the pump oil after the run, the oil 
filters and oil mist filter material. Also oxygen analyser could be purchased.