Summary of E614 Beams Subgroup meeting 2000/05/15

Present: J. Doornbos, D. Gill, P. Gumplinger, J. Macdonald,
G. Marshall, D. Ottewell, T. Porcelli, J.-M. Poutissou,
N. Rodning, V. Selivanov, H.-C. Walter

This is mostly from memory rather than recorded notes; please
send me significant corrections... GM

G.M. described a possible layout for measuring beam particle
positions and divergences using two fast wire chambers and
trigger scintillators. H.-C.W. pointed out that scattering in the 
vacuum window (assumed 50 microns mylar thickness) and especially in
the first of the two chambers (assumed 6 x 6.3 microns Al-mylar
plus wire planes) would dominate the mean divergence of the
measured beam such that measurements, at least with surface
muons, would be of reduced value.

Some alternatives were discussed. 

CHAOS could measure some of the relevant beam parameters, at
least at higher beam energies, but there are some drawbacks. The
CHAOS tracks would have to be extrapolated to a plane outside the
fringe of the CHAOS magnetic field. We would need to steal
dedicated CHAOS high intensity beam time in order to control the
beam (jaws, slits, magnets, etc.) to make most tests; low
intensity beam time would make BL1A monitoring difficult. Some
(not total) consensus was reached that this would not be
sufficient.

For surface muons, one chamber could be used in two different
positions to measure only beam profiles at those positions, from
which some idea of divergence could be inferred. Beam simulators
were not convinced that this information would be adequate to
validate their results.

Using a collimator some distance in front of one chamber was also
considered. This could give information on subsets of beam
particle rays which pass through the collimator to a measurable
position on the chamber, without appreciable scattering
uncertainties.

It was pointed out that D.G. and V.S. had made some measurements
in the past. These will be described by V.S. in the next meeting.

The possibility of conflicts, while trying to make measurements
at the same time that the yoke and solenoid are being installed,
was discussed. We are still unsure of the distance between the
end of M13 and the solenoid yoke, in which some or all of our
measuring apparatus must be placed.

Some discussion on the measurement of polarization occurred. This 
should occur at roughly the same time, but will require a
different apparatus (transverse field muon spin rotation).

Date of next meeting: Monday, May 29 at 13:00
Agenda so far: V.S. on previous measurements, software
requirements (requested by Maher), ...

-- 
 Glen Marshall                mailto:Glen.Marshall@triumf.ca
 TRIUMF, 4004 Wesbrook Mall   phone: 604-222-7466
 VANCOUVER, BC V6T 2A3        fax:   604-222-1074

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