[g2p_ana] Minutes of the septum meeting

[Jixie Zhang]

You can find Jixie's slices here:
http://www.jlab.org/~jixie/talks/SeptumField.pdf

On Mon, May 2, 2011 at 11:17 AM, Jixie Zhang <jixie at jlab.org> wrote:

> Minutes:
>
> 1) Jixie showed some slices to introduce the information and status of the
> septum:
> A) The filed map:  Bx vs. X|Z and By vs. X|Z, which shows that the current
> in the Tosca is opposite to the real
> B) Currently the septum center is located at z=686.46 mm, which is proved
> to be wrong.
> From Jixie's Geant4 simulation, it should be 772.40 mm, which is about 8.6
> cm more downstream.
> John's prediction also suggested some position down stream.
> C)Confirm by Al that the septum can not be moved at all due to the fact
> that there is no space down stream.
> D) With current design,  target located at -876.93 mm and septum at 686.46,
> the prediction bending angle by theory is 5.56 degree (some offset value of
> the septum itself not taken into account).
> E) Jixie's G4 simulation shows that the bending angle is 5.66 degree, using
> the septum map corresponding to
> 3400 MeV electron.   But we knew that the septum can not reach such a high
> current.
> F) Based on 2 map Robin provided, one for 400 MeV another one for 3400 MeV,
> Jixie scale the 400 MeV one by 8.5 then
> compare it with the other. There is about 0.2 Tesla difference in the
> field. which shows that in the 3400 map, the iron
> of the septum is saturated.  John mentioned that the number 400 and 3400
> itself could have large uncertainty due to
> the fact that these numbers is from a BdL accumulated along a straight line
> in the Tosca model, not the real trajectory
> of an electron.  But the conclusion that in high field of 3400 MeV, the
> iron is saturated holds.  Robin's "B vs I" plot also proves this.
> G) Robin provides the field map with the maximum current. The vertical
> range covers up to +/- 25 cm (requested by Jixie),
> the real opening is a rectangle with vertical cover +/-12 cm only.
>
> 2) The septum was found by Howard and John that there is one coil wired
> wrongly.  Jixie will schedule with Howard to
> make a cross check for each coil to make sure all coils are wired properly.
>
>
> 3) Al need to redesign the beam dump opening
>
> 4) Al need to change the design of the sieve slits.
>
> 5) Robin will try more efforts to check  the maximum current of the septum
> and provide a new map.
>
> 6) Once have the new map, Jixie will finalize the effect angle with Geant4
> then finalize the beam dump opening,
> also provide some fitting to Karl to calculate the kinematics and rates
>
>
> --
> Best Regards,
> Jixie Zhang
> Jefferson Lab - Hall A - A112,
> 757-269-5352
> _______________________________________________
>



-- 
Best Regards,
Jixie Zhang
Jefferson Lab - Hall A - A112,
757-269-5352
_______________________________________________
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