Re: MuCap structure

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

Dear Larry and Rick,

Again my apologies for not answering earlier, we just were totally
occupied with the experiment. I asked Penny to pay your June invoice.

On my last days at PSI I could get the required information, so that
we should be ready now for finalizing the concept drawing of the support
structure.

0) I updated the MuCap Webpage -> detector systems with info conc the
   support structure. I will refer to that page as WEB below. Also I
   included a list of relevant e-mails.
   Our coordinate system conventions is
   x horizontal perp to the beam
   y vertical
   z beam direction

1) The PSI surveyers told me that the floor of the MuE4 area where the
experiment is located this year is good to +- 1mm. For this year, we
will directly mount the rails on the floor. 
(If easily possible, we should foresee that the whole construction might
be put on a common plate later on).

2) The rails and wheel box will be provided by PSI. The PSI area
   coordinator made a sketch (see Koeferli on WEB). The rails are
   Type A55 from Pestalozzi (see WEB) and easily should carry 1 ton.
   The relevant height for starting the support structure is thus

   65 mm (rail) + 146 mm (wheel box) = 211 mm from floor 

 
3) We are free to select the distance between the rails. It just needs to
   be larger than the rails for the TPC rails defined in the MuCap.dwg.


4) As stated before, the critical alignment issue is between the ePC
   wire chambers and the TPC, to allow insertion of the TPC vessel. 
   The PSI surveyers suggested to support the ePC on 3 points, not 4
   as originally planned (for obvious reasons). These 3 support points
   then should be adjustable both in x and in y by at least 2 cm. The
   z (beam direction) motion is given by the rails.

5) 
> For the frame supporting the detector, one of you had stated that the
> rings should be aluminum, but that the rest could be steel.  I had assumed
> you meant stainless steel for magnetic reasons, but Larry suggested that
> may not be the case.  Is carbon steel acceptable anywhere?  Painted carbon
> steel would certainly be less expensive than stainless or aluminum.
Carbon steel should be fine 
 
6)
> Is a welded structure acceptable, or would you prefer that everything 
> be bolted together.  This may be affected by the organizations that 
> fabricate the components and assemble them on-site.  Welded would probably 
> be cheaper, but we are concerned that welding may not be easy for one or 
> more of the groups involved.
Please make a suggestion, what should be welded and what should be
bolted. To me it is mainly a transport issue, very big pieces are
more expensive to airship to Switzerland. Any comments, Eric and John?

6)
> 4.  Are the electronics racks 19" x 22" and is the 19" dimension parallel 
> to the beam line?  Do you have an estimate of the height?  If there are 
> cables attached to the backs of the cabinets, how much clear space should 
> we leave between the cabinets and the gondola channels?
Our racks are about 22" wide (in z ) and 30" deep(in x). Height about
80"(in y). Thus the depth of the standard racks is significantly deeper
than the crates(22"). I would leave about 5" clear space between the
gondola channel and the rack. If you think that the length of the
electonics support platform in x is a problem, we can consider using
special racks which are just as long as the crates and thus could
reduce the x length by 20" on each side.  

7) 
The estimated weight of the racks were specified by Steve in a separate
e-mail. Your static assumptions should be conservative. We expect you
to carry the responsibility for the static soundness of the construction. 

Please inform me, if you need any additional info. If not, please
finalize the *concept drawings* of the overall supports structure (as
discussed that does not include the gondola support, which will be 
done by Eric and John). We would then review the concept and discuss
who does the *detailing and preparation of bids*. This later issue
is mostly a budget question, and we have to see how much money is 
left after your concept is finalized. I had a brief discussion at
PSI conc the involvement of their workshop, it was not clear if that
will work on the short time scale required.

Larry, after you have read this mail, probably we should talk. I
will be around this week in my office or could call you.

With my best regards

Peter