E614 Magnet Status                 J.A.M.
                                                          9 April 1998
                     
Superconducting Coil

-a suitable coil (an obsolete MRI coil) has been identified available
for sale
 by Cryomag Services. We are currently attempting to contact the company
to
 firm up verbal quote for coil, and obtain a full system quote including
 crygenic transfer lines, cables, powersupply, quench monitor system. 
-details for inspection and acceptance criteria still need to be
clarified with
 the help of a qualified expert.
-the current reference design for field parameters and mechanical design
are
 based on this device.
 
Reference shield design

-OPERA2D calculations by Don Lobb gave an iron configuration giving the
 required field uniformity in the spectrometer region with a square
return yoke
 with a hole for the cryostat fill stack and no additional coils; this
was
 verified by Peter Gumplinger and Dennis Wright. 
-We need to check that (a) forces on the coil are also OK and (b)
 alignment of the bulk of the return iron is not critical, i.e.
determine
 tolerances.
-muon beam transport to stopping target needs to be finalized and
confirm
 that no additional coil is needed, and determine shaping of iron around
the
 hole. What are the tolerances for the entrance/exit iron w.r.t.
detector and
 beam?
-Some further optimization for cost and field requirements may be
possible.
 E.g. can the shield be shorter?

Square v. annular return crossection

Square has the advantages:
-can be fabricated from flat plates in modular sections (e.g.,sides,
ends, top)
 easier to handle and transport. At least one end and the top must be
removed
 for cryostat and detector installation and/or access anyway.
-is compatible with the floor-beam height and the cryostat dimensions.
Cylinder
 would require either distortion of the symmetry or a pit in the floor.
-mechanical design of removeable top and roll-away endplate is straight
 forward.
-amount of material is not drastically more; yoke thickness can be
thinner to
 conserve return crossection area (pi/4).
 
Square Shield design concepts:

-shield fixed in place except for (a)removeable top for cryostat
installation
 and access, (b)downstream endplate, and (c) upstream and downstream
hole
 collars.
-top has 40cm diam hole for He fill assembly. Removed by crane (approx
12 T).
-rear endplate (approx 6 T) rolls back approx 2 m on bearings; necessary
 structure for rigidity and stability.
-main chamber support cradle could be cantilevered on the back endplate
 although a detailed engineering study of this has not been done. A
fallback
 option could be a system of rails to support the detector with a
removeable
 extension to be installed when the detector needs to be removed. 
-indexing/alignment system for reproducible positioning of main chamber
will be
 needed.
-attached platform rolls with endplate for chamber frontend electronics
and gas
 system. 
-iron collar around beam hole for (a) precision alignment wrt beam and
chamber,
 and (b) modification/shimming for field.
-need to design necessary access holes in iron for cables an gas lines.
-layout in M13 illustrated in attached sketch. Actual location along
beam axis
 yet to be confirmed. Possible conflict with BL1B shielding wall for
rear
 endplate movement.

Costs and preliminary engineering assessment

George Clark has been assigned to assess this concept and determine a
rough
cost estimate. (The preliminary scaled estimate --- material by weight,
fabrication by surface area --- yielded a guesstimate of $125000). There
is no
TRIUMF budget for the shield in this year. 

Reference Nominal Dimensions
                      
Many of the following dimensions have been taken or scaled from drawings
or plots and may be prelimilary or inaccurate.  

Detector W.C.         O.D.	   750 mm    29.5 in
	              I.D.	   370 mm    14.6 in
    	              length	   900 mm    35.4 in
    
Cryostat   	      O.D.	  2100 mm    82.7 in
	   	      I.D.	  1000 mm    39.4 in
	   	      length	  2290 mm    90.1 in
	    	   total height   2495 mm    98.2 in
	    	   cyl. height    2140 mm    84.3 in

	    	   base - C.L.  	     43.0 in

Iron shield/yoke  length (inner)  3200 mm   126.0 in
		 	 (outer)  3400 mm   134.0 in
		  endplate thick.  100 mm     4.0 in
		  width/height
		 	 (inner)  2210 mm    87.0 in
		 	 (outer)  2540 mm   100.0 in
		  yoke thickness   165 mm     6.5 in
               entrance/exit hole  400 mm    16.0 in 
                     (diameter)

--
John Macdonald		phone: (direct line) (604) 222-7348  
TRIUMF 			       (switchboard) (604) 222-1047 
4004 Wesbrook Mall	fax  : (604) 222-1074 
Vancouver, BC		email: jam@triumf.ca
Canada, V6T 2A3

Filename: e614layout1.ps

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