Re: different quad for the tagger

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

Jim,

I think the inner aperture of 10mm radius is undesirable for the quad.  
This will change our halo spec.  Now that the halo looks non-existent in 
the machine simulation, perhaps we can live with it, but on the other 
hand perhaps we should take that with a grain of salt, given what we 
know about the 6 GeV beam.

The spec on the wiki that you refer to comes from just taking one of the 
standard machine dipoles and copying it.  Before we take and start 
rewriting the halo spec, I suggest that we quantify just how much money 
we save by going with these free quads instead of just asking the 
machine group to add one for us when they make their big order for the 
upgrade.  Are the savings sufficient to justify going back a redoing our 
spec?

Richard J.


Jim Stewart wrote:
> Dear Colleagues
>
> I believe I have found some quadrupoles available here at JLAB which 
> would be
> usable for the  tagger. The quadrupoles from the Helios transfer line 
> are available
> for us to use. I think we can use two of these quadrupoles for the 
> focusing magnet
> in the tagger. The specifications of the quadrupoles are given below 
> along with the
> requirements in the present design and the specifications on the WIKI. 
> Two of the
> Helios quadruples would be able to provide 14 T/m gradient over 400 mm 
> length.
> The present design calls for 5.2 T/m over 313mm. Therefore the Helios 
> quadrupoles would need
> to run at 4.1 T/m in our present design. This is 3.4 times less than 
> their max rating. This
> should be enough. Does anyone know why the WIKI spec call for 20T/m 
> and 400mm?
> The Helios magnets only have a aperture of 20 mm which is 
> substantially smaller than the
> 30mm in the WIKI spec. At present we are planning to use a 25mm 
> beamline through these
> quads so we would have to go to a smaller diameter pipe.
>
> The big advantage of these magnets is that they are free and we then 
> save 20K$.
>
>
> Jim
>
>
> Helios quadrupoles:
> =======================================
>   Aperture diameter                         20 mm ± 2mm
>   Magnetic length                             200 mm
>   Max magnetic field gradient           14 T/m
>   Field Uniformity                            1%
>   Ampere Turns                               2508 A-T
>   Maximum Current                         19A
>   Maximum Power consumption      192W
>
>
> Present Design:
> =============
>   Aperture diameter                         36.2 mm
>   Magnetic length                             313 mm
>   Max magnetic field gradient           5.2 T/m
>
>
>
> Wiki Spec
> ====================================
>  Aperture diameter                         30 mm ± 2mm
>   Magnetic length                            400 mm
>   Max magnetic field gradient          20 T/m