7 July 1995
To: Distribution:
From: Stan Ecklund
Subject: "IR +- 2m Engineering"  Meeting Notes 7 July 1995

Martin and Mike resolved a discrepancy in inner radius of the 
support tube which is 195.95 mm.

Mike presented calculations of the harmonic content of a hybrid 
quadrupole-dipole Q1 with trim coils.  He calculated harmonics at 
17 z locations, about the LEB axis at a radius of 10 mm.  The 
harmonics for the hybrid is better than for the offset Q1 by about 
a factor of 2.  (see transparencies for details)

Tom showed results of a Poisson calculation of fields from a 
hybrid 8 sector Q1.  Radial dimensions are from Mike.  Asymmetry 
in calculation has to do with Poisson meshing.  Overall result is 
encouraging with respect to block demagnetization.  More detailed 
calculations are to follow to quantify B component anti-parallel 
to block magnetization.

Dave reported progress in background calculations.  He has the 
newly frozen LER lattice into turtle to generate lost particles.  
The calculation starts outboard farther, midway in the arcs.  He 
assumes a vacuum of 1 nTorr inboard of 60 m and 10 nTorr outboard 
of 60 m and nominal 2 amp on 1 amp currents.  He modeled  LER 
collimators at 25 m (single jaw) and 49 m (two jaw).  The HER has 
single jaws at 10 and 32 m as before.  He has turtle generated 
rays as input to the detector simulation.  Shielding between B1 
and Q1 includes 0.75 inch of stainless steel to represent 
supports, and 2 cm of W which he switches on/off (off = air).  He 
also switches on/off 2 cm of W around Q1.  So far he has tallied 
hits on the outer drift chamber layer.  Switching on/off the 2 cm 
W is about a 30% change in the total background rate, almost all 
due to the change in the radiative Bhabba background.  The 10 
nTorr vacuum out board of 60 m is a significant contributor and 
should be specified to some lower value.  Next step is look at 
other detector components such as the calorimeter.

Martin and Fred discussed space issues at the inboard end of B1.  
It may be possible to shorten the first block in z by about 5 mm 
and compensate with smaller inner radius.  They will propose a 
solution and check with Mike.

Martin is keeping a list of services which come out the support 
tube ends.

Action Items:
1. Hybrid Q1 calculations. [Tom, Mike, Stan..]
2. Look for ways to reduce cable interference. [Roy, Fred, Alex]
3. Drawing Updates: [Martin Nordby, Fred Goozen]
     Shielding, cables in Q1 section
4. HOM RF calculations with new mask geometry.  [Eddie Lin]
5. Check that a rotated BPM misses synchrotron rad fan. [Mike]
6. Shielding calculations [D. Coupal]
7. Required thickness of Q1 containment. [Martin]
8. Required thickness of Support Tube,
   calculate support tube deflection. [Martin]
9. Mask & B1 3d cooling calculation. [J. Hodgson]
10  Beam generated noise to the drift chamber. [D. Coward]

No Meeting on 14 July due to PEP-II Rally
Next Meeting: 13:00 Friday  21 July 1995 in the Yellow room with 
TV to LBL

attachments: transparencies