DocumentCode :
408955
Title :
Lattice with smaller momentum compaction factor for PEP-II high energy ring
Author :
Cai, Y. ; Donald, M H R ; Nosochkov, Y.
Author_Institution :
SLAC, Menlo Park, CA, USA
Volume :
4
fYear :
2003
fDate :
12-16 May 2003
Firstpage :
2288
Abstract :
At present, the PEP-II bunch length and vertical beta function βy*, at the Interaction Point (IP) are about of the same size. To increase luminosity, it is planned to gradually reduce βy*. For the maximum effect, bunch length has to be also reduced along with βy* to minimize luminosity loss caused by the hourglass effect at IP. One of the methods to achieve a smaller bunch length is to reduce momentum compaction factor. This paper discusses a lattice option for the High Energy Ring,where the nominal 60° cells in four arcs are replaced by 90° cells to reduce momentum compaction factor by 30% and bunch length by 16%. The increased focusing in 90° cells results in 40% stronger,arc quadrupoles and 150% stronger arc sextupoles due to reduced dispersion and larger chromaticity. Tracking simulations predict that dynamic aperture for this lattice will be ≥ 10 times the rms size of a fully coupled beam for a horizontal emittance of 30 nm and,βy* = 1 cm. The lattice modification and results of simulations are presented.
Keywords :
beam handling equipment; electron accelerators; particle beam bunching; particle beam focusing; storage rings; PEP-II bunch length; beam size; dispersion function; dynamic aperture; fully coupled beam; high energy ring; horizontal emittance; hourglass effect; interaction point; larger chromaticity; lattice modification; luminosity reduction factor; momentum compaction factor; quadrupole focusing; stronger arc quadrupoles; stronger arc sextupoles; tracking simulation; vertical beta function; Acceleration; Apertures; Chromatic dispersion; Compaction; Geometrical optics; Lattices; Magnetic properties; Optical coupling;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the
ISSN :
1063-3928
Print_ISBN :
0-7803-7738-9
Type :
conf
DOI :
10.1109/PAC.2003.1289094
Filename :
1289094
Link To Document :
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