[Dlsupport] For your entertainment

[David Douglas]

Prinicipal rays through the 4F & 5F regions, starting at the end of the 
last optical cavity chicane dipole and ending at the reinjection point.

Two comments:

1) these can be used to cross-check other models (e.g. elegant as input 
to/extracted from LED)

2) the "parity" of the skew quads is ambiguous; prior running experience 
(with the 3F 5-quad rotator) suggests that the codes and EPICS disagree 
on what the sign - or coordinate system - should be or is). This can be 
resolved by "peering and steering": peer at the plots and then steer the 
beam. If you steer outward (right) in x, the beam should be going down 
after the 1st skew quad. If you steer up in y, the beam should be going 
inward (left) after the first skew quad.

Unless, of course, the coordinate systems and the sense of beam 
direction (direction of rotation around the ring) are not the same in 
the machine and them model. Which they aren't. But, hey, there's only 
three signs here: what is positive x, what is positive bend, and what is 
postive quad rotation angle, so there's a 1 in 8 chance we have it 
right... ;)


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