Separator thoughts

Separator mass resolution is an engineering issue, not a beam dynamics issue. Given correct mechanical, electric and magnetic field stability, can always get the resolution if not concerned about transmission. Transmission is a beam physics issue. It's meaningless to talk about resolution apart from transmission.

After 9 years of using the Chalk River separator magnet, we've never gotten close to the calculated resolution of 10,000. This is not because of anything intrinsically wrong with the separator.

We tune to get something like this:
(0.5mm by 12mrad)
taller one,
S-shaped one
Octupole movie

small emittance

But the high resolution design
was 0.13mm by 60mrad!:

from Pierres 97 paper

Or, comparing on the same scale:

(N.B.: 120 mrad full width is
24 cm wide beam in dipole centre.)

the 2 on same scale

We've never even gotten close. Why not?

We did not finish the engineering:

Why did we never carry out the good intentions?

Get the science out. Given a choice:

  1. Beam now, with some contamination, or
  2. allow beam physicists a couple weeks to commission high resolution,
experimenters prefer option #1, and learn to deal with the impure beam in another way.

Can we set it up once and forget it? No. A high resolution tune is hard to maintain because it is very fussy/sensitive to everything.

So where's the rationale for a resolution 10,000 separator?

What did we do right?

What have we learned (that we would do differently)?

What's a good compromise?

some math

So clearly it's not economically sensible to go to extremely high resolution.

Rick Baartman
Last modified: Tue Jan 22 22:38:00 PST 2008