Re: CDC report

["Curtis A. Meyer" <cmeyer@ernest.phys.cmu.edu>]

Hi Elton -

    the Rohacell has other issues. The design that we had
considered had us inserting the tubes into a Rohacell
holder. Because the tubes physically touch, this would
have required the drilled holes to all connect and the 
endplate would fall apart. 

    We did not consider a composite with skins, but at this
point you get to the skin being the dominant material. I 
have not had a chance to write things up yet, but we are 
looking at several possibilities:

  4mm G10      (have material in stock)
  6mm Delrin   (not sure we can get a big enough sheet)
  4mm Carbon Fiber (special order to get it big enough)
  Aluminum Honey Comb (skins get fairly thick for the stereo)

What we are doing is measuring "stiffness" before and after
drilling, and have data on the above. While the Delrin is not
real stiff, if we could support it during stringing, it would be
good. I am actually not convinced of the Aluminum Honeycomb,
but we have it and are looking at it.

  What we found with the Rohacell was that it was quite "crumbly",
little pieces falling off the edges. We could put a skin on it, but
it needs to be about 2.5 to 3mm to support the stero. This is not 
too different from some of the materials we are looking at above.

   I am convinced that we will have an endplate that has substantially
less material than the 6mm Al in the current design. I am just not
100% sure of what it is yet.

- Curtis


On Mon April 2 2007 14:31, Elton Smith wrote:
> 
> Hi Curtis,
> 
> I noticed today that Mike had prepared an update on the CDC for the
> collaboration meeting, although it was not presented. This is likely
> because it was scheduled originally and the lack of time. However, I did
> briefly take a look at it and have a question about the downstream
> endplate studies. One of the conclusions is that Rohacell will not work
> but the honeycomb is the most rigid. Since this was not discussed, I do
> not know if this was considered as a composite with skins. Clearly foam
> alone would not be sufficiently rigid, but our experience is that a foam
> composite with carbon fiber or stainless skins is as rigid as honeycomb
> and more uniform. Accuracy in drilling can be established in the skins
> with oversized holes in the foam.
> 
> Cheers, Elton.
> 
> p.s. I have also noticed that no one from the CDC group is subscribed to
> the halld-tracking-hw list and I have taken the liberty to add you to the
> list. This is one of the primary communication mechanisms for drift
> chamber discussion.
> 
> 
> Elton Smith
> Jefferson Lab MS 12H5
> 12000 Jefferson Ave
> Suite # 16
> Newport News, VA 23606
> elton@jlab.org
> (757) 269-7625
> 

-- 
Professor Curtis A. Meyer        Department of Physics
Phone:  (412) 268-2745          Carnegie Mellon University
Fax:    (412) 681-0648            Pittsburgh PA 15213-3890
cmeyer@ernest.phys.cmu.edu  http://www.curtismeyer.com/