31 March 1995
To: Distribution:
From: Stan Ecklund
Subject: "IR +- 1m Engineering"  Meeting Notes 31 March 1995

Martin showed sections of the mask on the up beam LER side with 
cooling passages indicated.  Sections are at z=0.25, 0.28, and 0.3 
m from the IP.  The mask would consist of slices brazed together.  
Adequate length of vacuum to water brazes must be maintained; it 
would be better to have no vacuum to water brazes.  A design which 
accomplishes this using copper rectangular tubing was also shown.  
It has the disadvantage of using more radial space between heat 
source and water cooling.  Mike will look at the possibility of a 
fourth mask tip based on the spacing shown.  Note that these 
figures are not yet flipped to the new orientation.

Roy gave a status on the attempt to remove the interference with 
the first block.  He believes he can by shortening the block by a 
factor of two and also shortening the first silicon layer.  This 
still leaves B1 too weak.

Stan showed the calculated fields for a geometry with outside 
blocks tapered.  A summary of the configurations since the CDR 
shows the taper can recover the B1 strength.  It would be more 
costly and more difficult to build.

Dieter reported on his looking into the feasibility of a tapered 
permanent magnet block.  It looks possible since blocks are 
usually cut with EDM from a larger log after sintering.  More 
study will be needed here, for example with the vendors that can 
supply the particular material we plan to use.

Stan showed study by Yuri Nosochkov on the quad strength changes 
needed to move the LER IP by 10 mm.  The answer is at most 0.6%.  
(see attached transparency for details).  Machine people are still 
reluctant to do this without a longer period of study.

The above study was for moving the IP with no change in magnet 
positions.  Hobey pointed out we could also consider keeping the 
IP to quad spacing the same and only shifting the B1 location.  
Mike suggested the two B1 magnets could be different to get the 
largest parasitic crossing separation for each case.  Given the 
masking is different this may help increase the strength of one or 
the other B1's.

Information on beam abort radiation detectors is still being 
collected.  Present thinking is to use four diodes around beam 
pipe on each end.  Some redundancy is required to avoid false 
aborts and ensure coverage.

Roy reiterated the schedule:
  6/1/95   Freeze silicon dimensions.
  5/1/95   Decide on B1 dimensions.
  5/15/95  Design review for B1 and freeze B1.

Action Items:
1.  Investigate B1 temperature stabilization.  [John H.]
2.  Try to fix interference of SVD with first block  [Roy K]
3.  Show location of SVD gimbals on drawing  [Roy K]
4.  Get radiation detector dimensions for drawing.  [Roy K]
5.  Investigate a four tip mask and reduced inner block 
    radius. [Mike]
6.  Refine mask and drawing. [Martin]
7. Number and location of holes in support barrel. [Gordon]
8. HOM RF calculations with new mask geometry [S. Heifets]

attachments: Transparencies

Next Meeting: 13:00 Friday  7 April 1995 in the Yellow room with 
TV to LBL