Problem with wire chamber support

[Larry Bartoszek <bartoszek@fnal.gov>]

Dear Peter,

     I am enclosing a section view through the detector to show you a
problem I have.  It looks like unless you can sacrifice a couple of the
electrical connectors around bottom of the outer wire-chamber, then I can't
see a way to reach in and hold up the wire chambers from the half rings.  It
is really a subtle problem that took me a while to appreciate.  You see, the
rings are further apart in the beam direction than the outer wire chamber is
long.  There is no direct radial connection between the half rings and the
wire chamber.  This means that the wire chamber support is cantilevered in
between the rings.  Either the end that connects to the lower half-ring, or
the end that connects to the G-10 support ring of the chamber must be bolted
down to carry a bending moment.  To make it alignable, it must be
positionable while it is carrying the bending moment.  This is interesting
but not impossible.  What makes the job look impossible is that the
connectors completely surround the wire chamber, and are at a larger radius
than the outer surface of the G-10 support ring at the ends of the chamber,
and there isn't enough room to get a cantilevered support in anywhere.
     The next subtlety arises from the way you said you want to be able to
insert the wire chamber from the end of the detector support, on rails.  You
said I can't bridge between the two rings with the rails because that would
shadow the scintillator.  Let's assume for a moment that you have eliminated
a pair of connectors at each end near the bottom to give me some room for
supports.  I can easily bolt a pair of rails onto the lower half ring that
points upstream so that the wire chamber can be lowered onto these rails and
shoved into the detector.  What happens when I have shoved the wire-chambers
part way into the detector and there is no rail in between the rings?  How
do you hold up the downstream end until it gets far enough inside to engage
the downstream cantilevered support?
     Once I assume that I have the room to make the supports attached to the
lower half-rings, it is easy to see how you could assemble the wire chamber
by lowering it straight down onto the lower scintillator half-ring assembly,
with the upper half off.  I don't know how to do the shoving in
longitudinally part.
     I need you to tell me exactly where you can make some space for the
wire chamber support, or tell me I can put them wherever I need them and
you'll adapt the connectors away from those points.  I also need the
diameter of that G-10 ring that I am supporting verified because I remember
you saying that things did not necessarily look like the drawing.  Talk to
you soon.

                  Thanks,
                  Larry

Bartoszek Engineering-- www.bartoszekeng.com

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