Subject:
Addendum to today's CESR-c lattice design meeting
From:
"James A. Crittenden" <critten@lepp.cornell.edu>
Date:
Fri, 10 Nov 2006 15:53:49 -0500
To:
Mike Forster <mjf7@cornell.edu>, Stu Peck <sbp@cesr10.lns.cornell.edu>, Maury Tigner <mt52@cornell.edu>, Dave Rice <dhr1@cornell.edu>, Jerry Codner <gcodner@lepp.cornell.edu>, John Sikora <JPS@LNS62.LNS.CORNELL.EDU>, Sasha Temnykh <abt6@cornell.edu>, Mike Billing <mgb9@cornell.edu>, David Rubin <DRubin@environmentaldefense.org>, John Hylas <jth@LNS61.LNS.CORNELL.EDU>

During today's lattice design meeting, DLR stressed
that the comparisons of dynamic aperture calculations
should be made at the same tune values. We had
been comparing a recent 3770 design (wip_2) at
its design tunes (0.518, 0.610):
http://www.lepp.cornell.edu/~critten/meeting/da_1537.pdf
to the 2005 lattice 3770_20050626 at its
characterization tunes (0.54,0.59):
http://www.lepp.cornell.edu/~critten/meeting/da_1425.pdf

Here is the 2005 lattice calculation at its design
tunes of 0.516,0.579:
http://www.lepp.cornell.edu/~critten/meeting/da_1429.pdf

At this lower value of the horizontal tune, the 2005
lattice still shows the more geometrical dynamic aperture
at zero positron current, but the aperture at 2 mA
positron bunch current is MUCH worse. Only bunch 5
survives up to 2 mA and its aperture is only a couple
of sigma. According to this comparison,
our new wip_2 outperforms the old lattice at high current,
while its horizontal aperture at zero current is equal to that of
the old lattice at low vertical amplitude, suffering only
at very high vertical amplitude.

The second loose end from the meeting was some duplicate
entries in the new plots showing the plane and position around
the ring where the losses occur. These have now been fixed.
wip_2:
http://www.lepp.cornell.edu/~critten/meeting/daplane_1597.pdf
20050626:
http://www.lepp.cornell.edu/~critten/meeting/daplane_1598.pdf

-- jim