In late September, we found during operations that the lattice
4260_092605_v1 exhibited improved injection and dynamic aperture
characteristics over the previous lattice 4260_min_v1.
MJF noticed the curious fact that the beta
function at the electron injection point was counter-intuitively
smaller in 4260_092605_v1. I added comments on wall clearances,
on the qualitatively different horizontal pretzel orbits wrt the
parasitic crossing points in the 9x5 configuration,
and on the influence of the BBI on the maximum beta around the
ring and on the Welch/Temnykh B parameter.
A web page summarizing this discussion is here:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/3oct05/report_03oct05.html

More recently, in response to a query from MAP, I added to the BBI
analysis some plots concerning alpha* and beam waist motion.
This discussion for the lattice 4160_fromdlr4200 can be found here:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/21oct05/report_21oct05.html

I thought it would be interesting to compare the alpha* and beam waist
plots for the two 4260 lattices to see if they might give an indication
of why one appeared to show operational advantages.
The two complete sets of BBI plots can be seen below.
4260_min_v1:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/31oct05/bunch_945
4260_092605_v1:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/31oct05/bunch_946

Perhaps the most remarkable difference between the two lattices
is that the horizontal beta function at the IP DECREASES from 60 to 50 cm
for 4260_min_v1 and INCREASES from 80 to 120 cm for 4260_092605_v1.
4260_min_v1:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/31oct05/bunch_945/P017.html
4260_092605_v1:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/31oct05/bunch_946/P017.html

The consequence is that the horizontal beam for 4260_min_v1 size at the waist decreases by
about 10% as the positron bunch current increases to 2 mA/bunch, while it increases
by a similar amount over the same region for the better-behaved lattice.
4260_min_v1:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/31oct05/bunch_945/P033.html
4260_092605_v1:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/31oct05/bunch_946/P033.html

The vertical beam size at the waist  due to the emittance and beta function increases
from about 0.52 to 0.54 microns for 4260_min_v1 while it is quite independent of
positron current at 0.49 microns over the same region for 4260_092605_v1.
4260_min_v1:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/31oct05/bunch_945/P032.html
4260_092605_v1:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/31oct05/bunch_946/P032.html

-- Jim

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James Crittenden                   Tel. (607) 255-9424
Wilson Synchrotron Laboratory      Fax  (607) 255-8062
Cornell University
Ithaca, New York 14853-8001
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