[Fwd: Re: Permanent magnet costs]

[Elliott Wolin <wolin@jlab.org>]

FYI:

Free permanent magnets from Fermilab?  See below!

Can we afford a 50 foot tunnel to house the magnets...alas, probably not.

Anyway, I received this from Fermilab.

				Elliott


==============================================================================


-------- Original Message --------
Subject: Re: Permanent magnet costs
Date: Mon, 15 May 2000 14:52:06 -0500
From: "G. William Foster" <gwf@fnal.gov>
To: Elliott Wolin <wolin@jlab.org>
References: <39202FA4.986DF97@jlab.org>

Hi Elliott,
    The cheapest thing that you could do would be to talk us out of
the four leftover vertical bend dipoles for the 8 GeV line.
Each of the four have physical length 145in, magnetic(pole tip) length
of 140in, magnet gap 4"x 2"(HxV) and integrated bend strength of
0.822 T-m.  So all four combined would bend a 12 GeV beam by
4*0.822/(BRho~40T-m) = 80 mrad =4degrees approximately.
This would require 4*145in of tunnel, is this is a problem?

These magnets were built and installed and worked fine but turned
out to be an aperture problem due to halo from Booster extraction,
and therefore were replaced by magnets with 3"x6" throats.  I don't
know what happened to them but if you are interested I could try to
track them down.

If you need to build stronger magnets but can live with a smaller
aperture then a good starting point is the 2-d cross section in
http://www-ap.fnal.gov/VLHC/vlhcpubs/pubs1-100/7/perm_magnets.pdf
which is a 0.7T design developed for 120 GeV beam transport lines.
My guess is that building 3 Tesla-meters of these from scratch would
cost $50K in EDIA and maybe twice this amount in parts, if you build
them the way we do at Fermilab. However if you build them at LBL
or LANL it will cost you more than $1M.

-Bill Foster


Elliott Wolin wrote:

> Hi,
>
> I saw your paper on the 8 gev permanent magnet design and was looking for some
> information.
>
> We need to build a permanent magnet for a new beamline at Jefferson Lab (aka
> CEBAF), and need some preliminary cost estimates.  The magnet is part of a
> safety system that keeps the (proposed) 12 gev electron beam from leaving the
> photon tagger building and reaching the photon experimental hall (normally the
> tagger magnet does this).
>
> We just need to bend the e- beam down a few degrees into the ground.  I guessed
> that a 4m magnet bending the 12 gev e- beam 3-5 degrees would suffice...I get
> 0.5-1T needed.  Active region probably 2cm x 5cm.  Precision is not
> important...this is the 3rd component of a safety system...just need to get the
> beam into the ground if the other systems fail.
>
> Any information you have would be useful...talking to one of you on the phone
> would probably be more useful!
>
>                                 Sincerely,
>                                         Elliott Wolin
>
>                                         wolin@jlab.org
>                                         757-269-7365
>
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