[Sane-analysis] Minutes of April 13 Analysis Meeting

[O. A. Rondon]

On Wed, 13 Apr 2011 18:51:25 -0400
  Narbe Kalantarians <narbe at jlab.org> wrote:
> > _*Whit:*_ Looked into scenario of if the target field was reversed.
> > http://quarks.temple.edu/~whit/SANE/talks/sane_magnet_reversed.pdf

Here are the results of my standalone code to track through the target
field, for 4.7 and 5.9 GeV. Whit is right that the beam center is
shifted up only a few mm at the target center.
http://twist.phys.virginia.edu/~or/sane/analysis/targeta.ps
http://twist.phys.virginia.edu/~or/sane/analysis/targetb.ps

The lines going exactly through the center are straight line projections
at the same starting angles.

But the 1 to 1.1 cm raster envelope hits the top of the cup for at least
the downstream half of the cup for 4.7 GeV, and for much of the same
region for 5.9 GeV. The target group should confirm if evidence for
radiation damage to the top of the cups was seen when the inserts were
removed.

In particular, the cups of insert C which were used without reloading
during the last part of the 4.7 perp data and the early part of the 5.9
parallel would have been more likely to show damage signs when removed
during the rotation from 80 to 180. Given the very shallow angle of
incidence on the cup's top, the damage would have been very substantial.

To make the plots I used vertical downward offsets at z =-150 cm from
the target center that correspond approximately to the numbers in the
chicane settings table. Keep in mind that those settings are for the
energies indicated on the table, but for the plots I used the actual
energies of the run. The offsets I used are -7.07 cm for 4.723 GeV
(table is -6.6 cm) and -5.7 cm for 5.892 (table is -5.6), which put the
bent tracks almost exactly at the target center.
http://hallcweb.jlab.org/experiments/sane/rondon/chicane.pdf

I used the vertical angles on the chicane table, although the exact
angles would be slightly different, at about the millidegree level.

The total deflection for 4.7 GeV is 5.8 degrees, which projects to 3 m
above the standard hall dump. In summary, it still seems unlikely the
field was reversed.

Cheers,

Oscar



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