Re: colli cave question

[Elton Smith <elton@jlab.org>]

Hi Jim and Richard,

The permanent magnets are worth considering, but I believe the integral
field is 0.82 T*m and the field strenght is about 0.23 T. See GlueX-docs
574 and 599.


Cheers, Elton.




Elton Smith
Jefferson Lab MS 12H5
12000 Jefferson Ave
Suite # 16
Newport News, VA 23606
elton@jlab.org
(757) 269-7625
(757) 269-6331 fax

On Thu, 22 May 2008, Richard Jones wrote:

> Jim,
>
> This is certainly worth considering.  The main concern that I see right
> away is the real estate.  Right now the sequence following the first
> collimator is 50cm (sweep) + 200cm (iron) + 100cm (concrete) + 50cm
> (gaps) = 400cm.  The iron is there to stop muons from muon pair
> production in the primary collimator and from pion decays.  I think you
> still need the concrete in the forward direction to attenuate the
> forward neutron flux.  All of this could be simulated.
>
> I suppose the permanent magnets are some ceramic material, right?  Any
> rare earths that might activate?
>
> Richard Jones
>
> Jim Stewart wrote:
> > Hello Richard
> >
> > I was wondering if it would be reasonable to take one of the permanent
> > magnet dipoles and use it as the first sweep magnet? The field is large
> > with 1.5TM and we can put spacers in the gap to reduce the aperture to a
> > 2cm hole. If you pack the whole thing in concrete then you still absorb
> > neutrons.
> >
> >   -------------------------------
> >   |                             |
> >   |         concrete            |
> >   |                             |
> >   ------------------------------
> >   |         | dipole |          |
> >   |         |   o    |          |
> >   |         |        |          |
> >   -------------------------------
> >   |                             |
> >   |                             |
> >   |                             |
> >   -------------------------------
> >
> > Maybe you need a concrete block at the back.
> >
> > This may even have enough field to not need a second magnet.
> >
> >
> > Advantages:
> >    We have the magnet.
> >    No active parts.
> >    Nothing to fail.
> >
> >
> > Dis-advantage
> > The magnet is 4m long.
> >
> > Is this worth considering?
> > Jim
> >
> >
>
>
>