Summary of 12/12/2006 CESR-c Optics Meeting
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9:30-11:15

We began by reviewing the luminosity performance
achieved since returning to the 2005 3770 conditions
last week.
An overview since 2003 of delivered luminosity per
day can be seen here:
http://www.lepp.cornell.edu/~critten/cesr/talks/12dec06/lumi1.pdf
Although the best day has provided less than half
the typical daily luminosity at the end of the 2005
running, the peak luminosity has reached 80% of
the 2005 level, as can be seen here:
http://www.lepp.cornell.edu/~critten/cesr/talks/12dec06/lum12dec06.pdf
The peak luminosity has now reached 4E31 in the
present 8x5 running configuration.

A comparison to the running conditions at the end of the
last 3770 in 2005, and to the running conditions at the end
of the 4170 run in April 2006 is given by comparing the previous plot
to this one:
http://www.lepp.cornell.edu/~critten/cesr/talks/12dec06/3770_2005.pdf
The more recent plot does not clearly show that we
are dumping electrons and refilling from scratch each fill,
even though we ARE, since the dots are not connected.

JPS pointed out that the characterization of yesterday afternoon
http://cesrelog.lns.cornell.edu/mslog/characterization/2006/auto_chardec11.html
shows two curiosities: 1) there is a big horizontal excursion in the
pretzel-off orbit in the west flare, 2) the horizontal phase has
a 20-degree error around the ring.

MJF assured us that the change in the layout file yesterday afternoon
is not contributing to any errors in phase measurement.

DHR showed a tonality measurement from yesterday and also relayed
a concern from DLH/RT that one source of optics errors may come
from field errors at pretzel maxima in the "more bends," in the north and near
the wigglers, which have an additional coil increasing the field
strength by 50%.

JTH reported on last night's studies of injecting into collision in 8x3.
These can be seen from about 2 am to 5:30 here:
http://www.lepp.cornell.edu/~critten/cesr/talks/12dec06/lum12dec06.pdf
Impressive specific luminosity was achieved at this higher bunch current,
resulting in operational peak luminosity similar to 8x5. Positron injection
into collision was not yet established, however.

Next steps following today's down will be addressing a number of outstanding
practical problems, such as an intermittent problem affecting stability of RF operation,
and recovering from some magnet re-alignments:
http://cesrelog.lns.cornell.edu/elog/2006/WEEK_50/TUESDAY.HTML#46
There was agreement on the urgency of understanding the strange
behavior of feedback at present, which JTH had to turn off completely during
his 8x3 studies to get injection, and the closure of the pulsed bumps in
both east and west. When/if these obvious problems can be understood,
the most productive short-term path to increased integrated luminosity
with low background is likely to be establishing 8x3 operation with
injection into collision. Investigation of alternative lattice designs
will be continued later.

-- 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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