Re: possible pair spectrometer magnets (fwd)

["Hrachya.Hakobyan" <hakopian@atlas.yerphi.am>]

Hello Jim,

I'm apologizing, I've missed to mwntion an  option 2, the H-shape magnet 
with Bmax*L>3 T*m, that is quite appropriate and might be used  
for PS construction. The problem of this magnet use might be rather 
technical due to its noticeable weight and sizes. I will try to evaluate  
this case for the choice of  B*L and vacuum chamber.  As I 
undertood you've asked me about that isn't it?  

Hrachya



On Wed, 4 Jun 2008, Jim Stewart wrote:

> 
> Hello Hrachya
> 
> I do not understand this. The vacuum chamber will need to be longer to
> insure that 12 GeV electrons don't go down the beam pipe and to give enough 
> space for shielding. The window cut out for the 9GeV particles also has to 
> be far enough from the beam line to have mechanical strength. These 
> criteria are directly affected by the Int[B*dL]. On the low energy side 
> the particles never hit the yoke on one side so as long as the particles 
> do not curl up inside the field you can still detect them.
> 
> I suggest that you look at what the vacuum chamber would look like for the
> 20x42 and then compare how the design would be with the 24-8-72. The 72 
> inch long pole gives plenty of Int[B*dL] and the 24" pole would still give 
> a uniform field over about 500mm even if we put plates in the gap.
> 
> 
> At some time we may need to exchange sketches.
> 
> Jim
> 
> >>>
> >>> Jim Stewart wrote:
> >>>> Dear tagger
> >>>>
> >>>> While at BNL I went looking for possible magnets for the pair
> >>>> spectrometer. I found several which look like good candidates.
> >>>>
> >>>> The 20x42 looks to be very interesting. It is a C-Magnet with the
> >>>> following characteristics:
> >>>>  pole width  508mm
> >>>>  pole gap    203mm
> >>>>  pole length 1067mm
> >>>>  Max field   1.85T
> >>>>
> >>>> The gap is too large but it would be easy to add plates to the poles to
> >>>> reduce this. A C-Magnet has the advantage that on one side of the magnet
> >>>> we can measure very low momentum particles. Installing the vacuum chamber
> >>>> can also be done without taking the magnet apart.
> >>>>
> >>>>
> >>>> The 24-8-72 is an H-magnet with a field clamp and relatively wide poles.
> >>>>  pole width  609mm
> >>>>  pole gap    203mm
> >>>>  pole length 1829mm
> >>>>  Max field   1.85T
> >>>> To reduce the gap here you would need to add tapered plates. This could
> >>>> be done but requires a simulation.
> >>>>
> >>>> The 18D36 is also an H-magnet. It has a somewhat narrower pole and is more
> >>>> compact.  (18" wide pole and 36 inches long)
> >>>>
> >>>> They may also have power supplies for the magnets above. We would need to
> >>>> install new controls in any supply we got.
> >>>>
> >>>> I feel that the 20x42 is a rather good match to our needs.
> >>>>
> >>>> Please let me know what you think!
> >>>>
> >>>> Jim
> >>>>
> >>>> ------------------------------------------------------------------------
> >>>>
> >>>>
> >>>> ------------------------------------------------------------------------
> >>>>
> >>>>
> >>>> ------------------------------------------------------------------------
> >>>>
> >>>
> >>> --
> >>> /Daniel Sober
> >>> Professor and Chair
> >>> Physics Department
> >>> The Catholic University of America
> >>> Washington, DC 20064
> >>> Phone: (202) 319-5856, -5315
> >>> E-mail: sober@cua.edu/
> >>>
> >>
> >
> >
>