Re: possible pair spectrometer magnets (fwd)

[Richard Jones <richard.t.jones@uconn.edu>]

Alexander Somov wrote:
> Hello Richard,
>
> Obviously I don't want to spend much time on optimizing
> beam line components and leaving them out from the current
> design.
>
> However, I get the feeling that the current design is not
> optimized:
>
> where do you get 0.2 T, 0.5 m long magnets from (do we have them
> in JLab) ? They seem to be rather weak...
>
> Just a simple example (based on p = 0.3 H R): 6 GeV electron
> flying along the beam is deflected by ~0.13 cm after the magnet
> and has a deflection angle sin_theta ~ 5e-3, i.e. it would go
> directly to the target (p = 0.3 H R). Most of low energy electrons
> will interact with a beam pipe after the collimator cave.
> There are quite a few electromagnetic interactions as there
> is no vacuum pipe before the second sweeping magnet (~3% rad.
> length). Do we need this background at all?
>
>
> Cheers,
>        Sascha
>
>   
Sascha,

The magnetic field integral of the sweep magnets has not been 
optimized.  I don't think that the SLAC publication stated what the 
sweep fields were.  At any rate, we postponed that optimization.  The 
number and order of the elements was taken from the SLAC beamline.  You 
are right, it is the field integral of those sweeps that needs to be 
optimized.  Once that is done, we can write a spec for the sweep magnets.

Richard Jones