[BTeam] XRs the culprits?

[Jay Benesch]

I have modeled the MXR as a vertical bend.  A decade ago this magnet was 
to have it's 11.5" pole chamfered to 9", 1.25" per side, leaving the 
pole face rectangular. This had no skew terms when I modeled it then. 
This is not what was installed.  There is a significant skew quadrupole 
term associated in Z with the tetrahedral taper that was machined only 
on the top of the pole. See images on the second sheet of the 
spreadsheet attached or the png attached.

The summary sheet has my previous results on the XH, XY and XT modeled 
as horizontal bends.  No skew terms.

The model has 355.15A in 60 turns per coil, value taken from early May 
allsave.  BdL on 2218 MeV path is 1.3871E6 G-cm vs 1.3950E6 in EPICS, 
0.57% low.  The BH curve used was that I derived to match MAN/MAM field 
maps up to 1.5T so I expected a better match to EPICS.

Also, the field just inside the Z boundary of this model is 0.8 G, a bit 
higher than I like to minimize back-propagation effects of imposing zero 
at the boundary.  I'm re-running the model with a larger volume of air, 
extending out to 10m vs 4m in the version evaluated in the attached.  As 
Steve pointed out when I mentioned this to him, this means this magnet's 
field extends far enough to affect nearby magnets.  We know the XT 
steers the injected beam; this probably does as well.

The XR steel core drawing is MAG0030010-1802.

Jay
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