RE: MuCap

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

Dear Larry,

Just a short summary of our MuCap discussion yesterday, with
the main purpose to keep Dave informed (who is taking care of
the gondola's within MuCap) and to not forget the follow ups
during my vacation.

Gondola's

Larry made several interesting suggestions to simply the design
and manufacturing:

- He is concerned that the edge tiling does not work because of
  tolerance problems if welding is done after machining. He
  suggested a different assembly techique, where the scintillators
  are positioned on two assembly wheels during installation.

- He suggested to simplify the 2 holders for tube and mixer
  in a single piece. Also he suggested a collar around the
  mixer which is then mounted to the holding piece.

- He was concerned about the plane alignment between tube and
  mixer surface. I gave him a PM with mechanics. We should send
  him one mounting ring for the mizer, which are currently made
  in Boston (Dave could you do that)

- We had some discussion how to minimize support material behind
  the scinitillators to reduce scattering. I formulated the
  criteria in the following way. If the support bar is close
  to the scintillator then we just should minize the overall
  material (using conventional material i.e. Al). However, it
  is an advantage if the support bar (with same mass) is at a
  larger radius, because then less particles will hit is (i.e.
  its solid angle gets smaller). We discussed connecting
  the PM support pieces with straight bars as an option.

Larry asked whether he has freedom to modify the
present design according to the criteria above and whether
his subcontractor of John should do the detailing. My answer
to the first questions was yes, for the second I still wanted
to discuss with Dave, but probably Eric and John are busy
with the scintillator production.

Overall det support structure.

- Larry pointed out that the short PSI platform won't help us :),
  For this year we have to build the construction from the
  floor. Larry will look into some standard rails and Peter
  will check the floor quality and mounting of the present
  rail during his visit at PSI early July.

- The chamber, electronics and cable weight was tentatively
  specified. Steve, please send us an update of that including
  a more accurate estimate of the cables.

- The chamber cables should be strain relieved by a ring mounted  
  on the lower part of the scint support ring, so that they stay
  in place when the upper barrel and chambers are lifted away.
  Larry will propose their position and mounting.

- The weight for the electronic crates should be better sepcified.
  Steve please estimate the weight for 3 filled crates plus
  rack on each side and send that to Larry. We should be conservative
  in this construction.

- The gondola support wheel and the gondola support should be AL, the
  rest can be steel.

- We don't worry about the magnet, the baseline design is that this is
  taken care of on the TPC frame.

- Fine adjustment on 4 places should support the wirechamber package.
  For the 2002 run we will use a smaller chamber EPC2 than indicated in
  John's drawing. The support ring of this chamber will be the 
  *inner* diameter of the fiber glass ring of final chamber
  ePC2 shown in outcad.. Eventually, when we have build the real ePC2 it
  should be supported on its outer diameter, of course.

- Peter will try to get the PSI design of the TPC vessel translated 
  into STEP 203 or 214.

- Peter will send Larry his Adad sketch of the support structure.

Peter suggested to explore the possibility of (free) construction at PSI,
but the obstacles regarding a transition from English to European
seem immense.

Because of the significant workload we have postponed the shipping to PSI
date from mid Aug to Mid Sept. Only about for 4 gondolas should be shipped
mid Aug.

Larry will prepare the drawings for bidding, and bids will go out to
Boston and other vendors.
The next step is a design by Larry to be sent to Peter and Dave
for review.

Please update and correct.

With best regards

Peter 
   

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