11 August 1995
To: Distribution:
From: Stan Ecklund
Subject: "IR +- 2m Engineering"  Meeting Notes 11 August 1995

John Seeman asked about beam loss monitors.  Space for 6 is 
reserved in both forward and backward directions.  Pat Burchat is 
working out the details.

Roy described the SVT cable runs out along Q1.  The solution uses 
12 mm of radial space over 60% of the azimuth.  In addition there 
are 1/4 inch cooling lines, 3 on the top and 5 on the bottom and 
one nitrogen line.  The scheme only works for a centered (hybrid) 
Q1 and the support tube must be straight under load.  The Q1 cross 
section shown last week had 15.3 mm available for cables and 
clearance, so 3 mm is left for assembly/clearance.  Next step is 
to add machine cables and cooling on drawing.

We discussed the major issues remaining to resolve support tube 
size:
1. Do the cables and all utilities fit?
2. Can the radial field problem on backward DIRC end be solved?
3. Is there enough space for Q1 containment and supports?
4. The current has no tungsten shielding; is that OK?

We brain-stormed solutions to the Q1 radial field problem.  Ideas 
presented were:
1. Since Br ~ r can you reduce to outer diameter of the PM blocks 
near the solenoid pole. 
2. Make the solenoid field go outboard to the end of Q1.
   (-) this makes Q2 shielding harder because of DIRC gap.
3. Leave PM blocks out of region with radial field (~200 mm) and 
compensate with blocks elsewhere or stronger blocks.
4. Decrease aperture of inboard portion of Q1 to compensate.
5. Refrigerate blocks to improve ability of blocks to resist 
demagnetization. (liquid N2 or Freon cooling or ?)  
   (-) requires space for insulation.
6. go back to a superconducting solution for Q1, possibly simpler?
7. Arrange for solenoid to provide 2 kG transverse field rather 
than dipole blocks of Q1.
8. Rotate easy axis of blocks into z plane to be perpendicular to 
field.
9. Use Meisner effect to shield Q1 from solenoid field.  This 
pushes the field lines in a manner to affect Bz uniformity.
10. Spread the Br field out over greater z distance, decreasing 
it's magnitude. (see last weeks notes)
11. Concentrate the Br field to a small region of z and omit 
blocks there.

Program to follow:
1. Get more information on block materials from vendors.
2. Do tests on a variety of materials from several vendors.  Get 
sample pieces, measure before and after attempts to demagnetize.  
We potentially have pieces from the SLD prototype PM quad, and 
others?
3. Continue to look for ways to reduce demagnetizing field.


Action Items:
1. Hybrid Q1: [Martin, Tom, Mike, Stan, Max, Artem.]
     Demagnetization properties of REC (Sm2Co17) materials.
       * Vendor information
       * Block tests
     Required strength of Q1 dipole trim.
2. Machine and SVT Cables and utility routing. [Martin, Fred]
3. HOM RF calculations with new mask geometry.  [Eddie Lin]
4. Check that a rotated BPM misses synchrotron rad fan. [Mike]
5. Shielding calculations [D. Coupal]
6. Required thickness of Q1 containment. [Martin]
7. Required thickness of Support Tube [Martin, J. Hodgson]
    calculate support tube deflection;
    earth quake deflection.
8 Beam generated noise to the drift chamber. [D. Coward]

Next Meeting: 13:00 Friday  18 August 1995 in the Yellow room with 
TV to LBL