Carl-
	your points are well taken, but I was not refering to the orientation
of the beam line in my note.  I was refering only to the uniformity of
the field map, as a consequence of the alignment of the solenoid to the
yoke.

			nate

Carl Gagliardi wrote:
> 
> Nate:
> 
> My guess is that we (ultimately) need better than ~1mm transverse alignment,
> but I won't claim to know what we should call "zero" for purposes of
> evaluating how close we are.  In particular, we know that the beam wants to
> center itself order of a mm off the nominal beam alignment axis, and Jap's
> polarization calculations indicate that is enough to be of some concern.
> But right now, I don't know whether the "right" thing to do is reconfigure
> the channel to put the beam where it "should" be, while putting the solenoid
> on axis, or to accept where the beam wants to come out of the channel and
> align the magnet to match that.
> 
> >From your numbers, it looks like we may anticipate a tilt in the field of
> order 1/2500 ~ 0.4 mrad.  This level of misalignment between the beam and B
> field is not a problem {1-cos(theta)<10^-7}, but we do need to align the
> detector package to the B field to slightly better than this level of
> precision.  So this is the kind of tilt that shouldn't hurt us -- so long as
> we know about and account for it properly.
> 
> Carl
> 
> +-----------------------------------------------------------------+
> | Carl A. Gagliardi                                               |
> | Cyclotron Institute              Phone:   (979)  845-1411       |
> | Texas A&M University             FAX:     (979)  845-1899       |
> | College Station, Texas  77843    E-mail:  cggroup@comp.tamu.edu |
> +-----------------------------------------------------------------+

-- 
Nathan Rodning, Associate Chair
Professor of Physics
University of Alberta
Edmonton, Alberta   T6G 2J1
Canada
(780) 492-3518  /  Fax:  (780) 492-0714
http://www.thehungersite.com/

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