Re: Tuning Hall B collimator (fwd)

[Elton Smith <elton@jlab.org>]

---------- Forwarded message ----------
Date: Tue, 12 Jun 2001 11:25:33 -0400
From: Jay Benesch <benesch@jlab.org>
To: Elton Smith <elton@jlab.org>
Cc: Richard Jones <jonesrt@uconnvm.uconn.edu>, sober@cua.edu,
     Jim Kellie <j.kellie@physics.gla.ac.uk>, krafft@jlab.org
Subject: Re: Tuning Hall B collimator

After my experience last Friday in trying and failing to steer the B
electron beam through the collimator with less than half the throw
planned for hall D photon beam, I think I need to go back to the hall D
optics and give myself some more room for corrector pairs on the surface
by shortening the ramp length.  In other words, no locations beginning
at the radiator building wall upstream of the radiator proper would
change.  What will suffer is dipole margin, which is now sufficient for
24 GeV.  Vertical emittance will increase a bit, but I can deal with
that in the final triplet.  We'll probably need a stronger corrector
than any we now have, perhaps with 6mm laminations for relatively fast
response in a feedback loop.  These should go after the final triplet.