Re: Problem with wire chamber support

[Peter Kammel <kammel@npl.uiuc.edu>]

Dear Larry,

Your questions should have been clarified qualitatively in our telephone
conversation yesterday.

For quantitative information I send you John's e-mail with the attached
light guide dwg's. I measured the dimensions in this drawing. That should
give you more space.

Regarding the wire chamber dimensions (to be verified) there is a copy of
the original PSI drawings on the detector systems subpage under
heading electron detectors. The dimensions are for Kammer 3 and 5. i.e.
the chambers we will be using eventually. The 
OD of ePC2 ( measure V) = 677 mm, 
the length to the end of the G10 rings (measure I)=910 mm.

Please keep in mind (as discussed) that for the first run chamber 5 won't
be ready, but we will hold the chambers on the outer of the two
green connecting rings (which are clearly shown in your drawing). The OD
of this connecting ring equals the ID of the ePC2 G10 ring. If you have
troubles supporting this point, we will mount some intermediate structure
on the green ring to extend it to the size of the G10 OD.

I hope the wheel question is clarified now after receiving the photos.
As discussed, please leave the strain relieve to us to reduce the cost.
We should stay within the 20K boundaries.

Thanks for your timeline memo and the bill for July. The timeline is
pretty obvious to me, but what I am missing in the summary is
a clear statement what has been achieved by the end of this billing
period, and what remains to be done. Could you please provide
such a statement.
Also, in an earlier bill  (May) you promised a forthcoming report on
the magnet forces. I don't want to hold you up with that stuff this week,
but when the job is done we are still interested in Rick's report. 

Good luck and best regards

Peter 


On Sun, 4 Aug 2002, Larry Bartoszek wrote:

> 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
> 

Peter Kammel  /  pkammel@uiuc.edu
Department of Physics, Loomis Laboratory
University of Illinois at Urbana-Champaign
1110 West Green Street, Urbana, IL 61801 
Tel (217) 333-5424 / Fax (217) 333-1215