[Halld-tagger] Tagger magnet excitation studies

[Alexander Somov]

Hello all,

I don't think that we'll need any answers/decisions before.
Dan will be traveling, but we can certainly discuss the strategy
during the next meeting.

Cheers,
       Sascha


On Thu, 13 Jun 2013, Richard Jones wrote:

> Hello Dan and all,
>
> Let's put this at the top of the list for the next biweekly meeting's agenda, 
> on 6/24.  Sascha, do we need answers before then?
>
> -Richard J.
>
> On 6/11/2013 4:09 PM, Daniel Sober wrote:
>> I have finally gotten around to analyzing Yang's Tosca midplane maps at 
>> excitations of 6, 9, 12, 14, 15, 16 and 17 kilogauss.  The results are 
>> posted at http://faculty.cua.edu/sober/HallD/Excitation .
>> 
>> The most informative single plot is probably the one labeled "Plot vs B" 
>> (http://faculty.cua.edu/sober/HallD/Excitation/Bnorm_vs_B.pdf). If the 
>> permeability were infinite, the field per ampere-turn would be constant at 
>> about 0.83 gauss/amp-turn.  The figure shows that the saturation effects 
>> are already significant at the operating field of 15 kG.  If you look at 
>> the "fine" plots of B/NI versus z, you will note that the saturation 
>> effects are not uniform through the magnet.  For B>15 kG, the field at the 
>> ends of the magnet (z = ±300 cm) is slightly higher than the field at the 
>> center (z=0), while at lower fields the z-dependence is negligible.
>> Conclusions for mapping:
>> 1.  If there is any possibility of running above 12 GeV, we must map at the 
>> highest conceivable field.  (What is the expected power supply limit?)
>> 2.  To allow for running at beam energies other than 15 kG, we should map 
>> the magnet at 16, 15, 14, 12 and 6 kG.  Some of these maps may be made at 
>> coarser granularity if time is short.
>> 3.  Note that the Tosca calculations were made using the "default steel" 
>> permeability table, so we must make measurements at several excitations to 
>> test the reliability of the Tosca calculations.
>> 
>> I will be traveling in Europe from June 13-July 14.  See you next month.
>> Dan
>> -- 
>> /Daniel Sober
>> Professor
>> Physics Department
>> The Catholic University of America
>> Washington, DC 20064
>> Phone: (202) 319-5856, -5315
>> E-mail: sober at cua.edu <mailto:sober at cua.edu>/
>> 
>> 
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>
>