[b1_ana] Follow up on Re: Fwd: Re: A_PV with Deuteron Target

[Donald G. Crabb]

Hi Oscar,

 The angular openings for the Hall B magnet are the same as for the late lamented Hall C magnet, ie +/- 17 degrees in transverse and +/- 50 degrees longitudinal. Surely the target group must have drawings. I have a folder of the early draft drawings but not the as-built ones.

   Don








On Mon, 20 May 2013 14:32:00 -0400
 "O. A. Rondon" <or at virginia.edu> wrote:
>One more thought: since the plan is to use the Hall B coils, the option
>of suppressing A_V^d by aligning the field along q is very restricted.
>
>I don't know very well the geometry of those coils, but I found a hand
>sketch on the JLab Target Group pages (there must be something more
>professional somewhere). From the numbers there I get that the coils
>could be rotated to a maximum theta_q < ~ arctan(8/(19+4) = 19 deg,
>keeping a 1 cm upstream clearance for the slow raster's 1.1 cm radius
>envelope.
>
>Given the uncertainties in surveys, and beam wandering, especially with
>a chicane (needed to correct the beam deflection for rotated coils,) 1
>cm is the minimum clearance I would advocate.
>
>The dimension along the beam to the target center 19cm + 4 cm comes from
>taking 1/2 the coils' 8 cm split, per NIM paper on the CLAS target. If
>one sticks to the numbers on the sketch, the target center is at 19cm +
>9cm (per note on the right), so theta_q < 15.9 deg.
>
>The above consideration indicates that it's most likely that my 19 deg.
>estimate is way over optimistic, and since our two high x points have
>theta_q > 19 deg., trying to align the field along q to suppress the
>target-only A_V^d does not compensate for the trouble of setting up the
>beam line.
>
>The rough sketch of the Hall B coil dimensions is here
>https://userweb.jlab.org/~ckeith/EG1/Autopsy/banjo_dim.jpg
>
>Again, I encourage everyone to review the above points carefully.
>
>Cheers,
>
>Oscar
>
>
>
>
>

-------------------------------------------------------------
D. G. Crabb
Research Professor of Physics
University of Virginia
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