[G14_run] linear polarization

[Ken Livingston]

Hi All,
I made a rough fit to some of the collimated data with linear 
polarization from the test we had 4pass beam.
The fractional energies we ran at were about the same as those which 
will be used for 5 pass beam.
ie E_edge_4pass ~ 4/5 * E_edge_5pass

The results look good:
http://nuclear.gla.ac.uk/~kl/g14/

The peak polarization is ~86% at the lowest energy setting, dropping to 
~81% at the highest energy setting.
PARA is slightly broader than PERP, as we saw online.

For all peak positions the mean polarization should be over 75%.
At 5 pass the results should be the about same.  I'll produce some 
similar plots for the 5 pass data soon.


Cheers,
Ken