Minutes from weekly target meeting held 26th of July 2002 in building 888

a) Meeting to discuss long term planning of COMPASS polarised target
until 2005 (man power, financial issues etc) will be held in the
first days of September at CERN. A date proposed by Werner is Thursday 5th 
of September at 18:00, since the Nagoya members are at CERN at that time.
From Helsinki Peter Berglund prefers a few days earlier date.  From Bielefeld
not yet any comments. The purchase list for 2002/2003 will be discussed in
this meeting. The list needs to be update before the meeting. On the list 
renewal/modification of microwave PSUs, servicing of magnet solenoid PSU etc.
Also the possible production of spare 6LiD target material can be discussed.

b) The first offer for the Siemens Simatic S7-300 PLC is 2 253 CHF from IT/CO.
A 116 mm x 87 mm touch screen TP170A (black and white) is 704 CHF and
same size in color TP170B is 1417 CHF. The price for OP-170B with normal 
membrane keys should be checked. Norihiro made the first exercise to program
such a PLC using ladder diagrams for control of LN2 filling.

c) Kaori produced the preliminary polarisation file for the run 2002 until
26th of July. Average saturation polarisation stays very well constant. 
The spread in measured polarisation values between different coils looks 
similar to the 2001 data. The maximum positive values are measured by 
coils #7 (56.5 %) and #8 (57.6 %) close to the maximum of 57.8 % for 
coil #1 and 56.7 % for coil #5 in 2001 run. The coils #9 and #10 measure
52.1 % and 51.8 % using the preliminary TE-calibration. Thus the spread 
for positive side compared to average (53.3 % 2002 and 54.2 % 2001) is 
8.1 % (coil #8) for 2002 while for 2001 it was 6.6 % (coil #1). 

Note that in the 2001 the upstream had positive polarisation while for 2002 
until now the down stream has had positive polarisation. The same coil 
positions gave 2001 high negative polarisation results (but we should be
careful when comparing positive and negative polarisation values). 

Comment from Jaakko about the spread in polarisation measurement: 
if the average spin temperature measured by the coils is about 1 mK, 
this means that one coil is measuring Ts 1.08 mK while the 
other 0.97 mK - since the material is cut into many small pieces with random 
crystal direction (practically no interaction between the beads) and there 
is no spin ordering or other phenomena to get coherent spin system
and the spin system is very well isolated from lattice - 
this does not seem so surprising.

d) The EPR line should be used to verify the measured polarisation values.
This can be done with the EIO tubes, but the IMPATT diode system from
Bochum is prefered due to the smaller noise.

e) The schedule for the transverse spin mode was discussed in the weekly
COMPASS meeting. 

	1) On Wednesday 31st during MD the field rotation is stopped
	in the middle with zero solenoid current. The polarisation is 
	checked for about an hour in the longitudinal mode before starting
	the field rotation. The transverse mode measurement is started after
	16:00. 

	2) On Thursday or Friday the field rotation is continued to check 
	the polarisation in the longitudinal field. After this the field 
	rotation is started again and stopped at zero solenoid current.
 
	3) The transverse mode continues until MD of Wednesday 7th of August
	10:00. After this the polarisation is again checked in longitudinal
	mode. The polarisation is then destroyed by setting solenoid current
	to zero or by going to high temperature of 1 K to see spin 
	magnetisation relaxation to zero polarisation value.

	4) The polarisation is rebuilt with positive polarisation in the 
	upstream target cell and negative in the down stream target cell
	in longitudinal mode until Saturday 10th of August.

	5) On 10th of August at 10:00 the field rotation is paused in the
	middle with zero solenoid current. The transverse field mode is 
	continued until Saturday 17th of August 10:00.

Some precautions: the dipole PSU was serviced by Corryl before it was put into
use, never the less we should check that there is no excessive heating
in current lead connections or some where else during the long high power
operation, probably it is better to remove back panel of dipole PSU, the trim
currents should be set to zero for the transverse mode operation.

f) Kaori checked the change in the integrated areas of D, 6Li and 7Li NMR
signals before and after field rotation. The change is well reproducible
and seems to give the same relative magnitude for all the three spin 
materials when going from positive field to negative and back.

g) The field rotation from Wednesday 24th of July is done at 10:00, 18:00
and 02:00. It is not necessary to remove the production target. Before
24th of July the field rotation was done after 12 - 13 good runs.

h) Ishimoto commented that the NMR coil problem resembles the problem
of deuterium coil made of CuNi foil in SMC -94. Werner said that
the problem is now only in the upstream target cell. Jaakko said that
the material filling is now better than it was in 2001. The target material
of 2001 was weighted by Jaakko, Kaori and Naoki in April/May. This data can
be used to estimate the filling factor of 2001 (add to to-do list).

i) Werner told about plan to organise 3 day polarised target workshop at
Bonn 2003 end of October.

j) Fabrice corrected some calibrations of dilution cryostat parameters
on the target web page.