CDC configuration

[Beni Zihlmann <zihlmann@jlab.org>]

Hi All,

I had some information exchange with Slava this morning. And I realized many
different parameters and issues regarding the end-plate are not familiar 
to everybody.
like the following:
1) from mechanical tolerances there need to be a "gap" between tubes
     in a given layer of about 0.1mm to 0.15mm depending on the tolerances
     of the tube itself and its parts at the end.
     this is true not just at the end-plate but also at the center of 
the CDC for axial and stereo layers.
     Distances of 20 micro meters between straws is not realistic 
considering that there are no
     numbers available for tolerances of the tube diameter, wall 
thickness, glue joints, etc.

2) at the same level one could rather change the number of tubes in a 
given layer then changing
    its radius and play with the gap between straws (-> point 1)

3) there needs to be sufficient spacing after the last straw for the gas 
cover sheet and
    the support rods (about 1.9") as well as the suspension mechanism.

4) since the straws have to be custom made one could think of make them 
a few micro meters
    smaller in diameter to fit 28 layers in the allocated space.

5) the holes into the end plate have to be specified with position and 
angle such that a CNC machine
    can be programmed accordingly.

6) ...other points ??

we really need a meeting to discuss this with all parties involved to 
settle all the issues once and for all.
If we could meet still this week would be great.  How about
Thursday late afternoon say 4:00pm  ?
or Friday morning         say  9:30am ?

cheers,
Beni





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Benedikt Zihlmann
TJNAF
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tel: 757 269 5310 
fax: 757 269 6331                zihlmann@jlab.org
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