Minutes from target meeting held on 28th of February 2003 in 892-1-B09

a) Jaakko presented updated target planning and possible warming up rates for
the target magnet to discuss about possible hadron run. The broken roots
pump will be back at CERN around 18th of March. For the Alcatel rotary pump
the repair is expected soon. The material for the new helium pipework has
been received and the work can start soon. The NMR system with target holder
will be prepared after 17th of March. The plan is to start cool down of the
magnet around 11th of April so that it would be at 100 K before Easter.
Thus the material loading could be done on 22nd of April just after Easter.
The target would be ready for polarisation on 12th of May giving some extra
time if there are problems in start up. If the exercise to rotate the target
platform is done after 17th of March, about 3 weeks of extra delay in starting
of the polarised target can be expected. Thus the target would be ready
in the beginning of June or in case of problems later. 

The LHe evaporates from the magnet in 4 - 5 days. If no special effort is 
done the magnet warms up to room temperature in about 50 days. During the
problems of last spring the magnet was warmed up to room temperature in
20 days. If in the end of the muon run there is short 3 days TE-calibration
and the target platform is removed from the beam, the work is expected to take
about 2 weeks. Without TE-calibration and target platform rotation about
1 week. In this planning the magnet has to be moved while it is still
cold about 100 K or below.

b) Stepan summarised the weight measurement of the target material. The values
corrected for the pt100 thermometer are 165.8+-2.4 g for upstream and 
181.1+-2.4 g for downstream. The thermal shrinking of the Kevlar support 
structure used in the target cells was measured by cooling a rod 
and a cartridge to LN2 temperature. No measurable shrinking could be observed.
Thus the uncertainty in the volume is coming from the manufacturing tolerances,
which are conservatively assumed to be diameter 30+-1 mm and length 600+-2 mm.
This gives target cell volume of 424+-30 cm^3. Thus using material density
0.807 g/cm^3 this gives upstream packing factor 0.49+-0.05 and downstream
0.53+-0.05.

c) Yuri said that dispersion corrections could be used to determine more
accurately the frequency shift between positively and negatively polarised
NMR-signals. There is some distortion at high polarisation which is seen
in the local field plots. 2002 data would be interesting since the coils
were outside and different diamagnetisation factor can be expected. Yuri
suggested that the NMR-line shape could be published. Jaakko said that
he had already shown some of these lines fitted to memory function. This 
fitting gives second and fourth moments, which can also be calculated from
the microscopic theory of dipole-dipole interaction. Yuri said that
the local field data is in good agreement with the theory to about 10 %.

d) Norihiro had programmed the PLC system to control valves on the platform
vertical/horizontal screen bypass, 48 V turbopump gate valve, and to
start the 48 V turbo pump system. The vacuum can be monitored with a pirani
gauge in the PLC system in case of a power failure. Also the main still
line gate valve VH1 can be controlled with interlock to its bypass VH2.
The cabling in the pump room for the PLC system was finished by Jaakko
except the pt100 LN2 level gauge, which has to be still done.

e) Fabrice had implemented a new alarm system, which sends a SMS to target
phone if there is problem. Yuri asked if we could have more mobile phones
for the target. 

f) Kaori was looking at the systematic errors in polarisation data. 
Simulations of the mutually coupled NMR-coils were started with Aplac.
Yuri suggested the upstream error could be determined from the change in
the areas after field rotation. Later Jaakko suggested to Kaori that 
the case of high polarisation with all coils measured simultaneously could
be compared to the case when the polarisation was measured coil by coil
to determine to error from the mutual coupling. Assuming geometry 
80 cm x 6 cm for the ground loop its inductance can be estimated to be 
about 1.5 uH for 1 mm wire. The self capacitance of the microwave stopper
can be estimated from simple sphere model to be about 2 pF. Thus the 
resonance frequency of this system is about 90 MHz. In the worst case the
resonance frequency will be at NMR frequency and there is strong coupling
between the coils. The mutual inductances can also be estimated, but needs
3 dimensional modelling of the system.