different quad for the tagger

[Jim Stewart <jstewart@jlab.org>]

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