Subject: g-2 Ring News
						1 April 1996
						G. Bunce

g-2 Ring News
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	We will meet today in the large conference room, AGS, at 3, to
summarize our understanding of the coil motion and the fix.

	Bill is writing a detailed note on the work.  Very briefly, we
have found that the coil takes an oval shape with 4 stops, based on Sergei
Redin et al.'s radial field measurements.  Chien Pai has modeled this (3D),
and obtains very good, qualitative, agreement with our observations.  The
qualifications are that we find that the radial force on the coil, as given
by 2D modeling, depends very much on the mesh used.  Chien's results match
observations for a force within the range of the field model.  These results
include steps--the coil will move to a new stable position at one current,
then to a new stable position at a higher current.  It is qualitative because
these steps depend on friction on the stops.  Francis Farley has studied
the buckling of an I-beam analytically, and his result is that with 4 stops,
the coil will go oval somewhat above half-current for an assumed force in the
range of the field model.  For 8 stops, the coil would be stable for any
current.  We have also tested the straps for azimuthal motion--they can bend
the amount seen elastically, and also contribute to the restoring force
which acts to keep the coil from becoming oval.

	The proposed plan is to use 8 stops, with larger diameter stoppers.
The forces on the coil, stops, and cryostat are much larger, but a factor of
2 lower than acceptable limits.  The forces come from the 3D model, and have
been checked analytically.  We are exploring using a very nice spring system
developed by Lou Snydstrup and Jim Cullen, which would reduce the forces, and
still provide fixed coil position.

	The coil has been lowered 2 mm.  The new position is based on Chien's
3D modeling.  We are also installing 7 windows so that we can monitor the coil
position at each step, radially, vertically, azimuthally.  Flanges for the 
windows and new stop design were produced by BU, welded into place, and we are
testing the changes for vacuum tightness.

	We expect that the remaining ring work will take 1 month.  We also have
a cryo problem that developed--a bad leak in the 1st heat exchanger in the
cold box.  The cryo group is preparing an external heat exchanger, and this
work will also take 1 month.  Therefore, we expect to start cooling again
May 1.