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MOPLS050 |
Combined Phase Space Characterization at the PEP-II IP using Single-beam and Luminous-region Measurements
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655 |
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- A.J. Bevan
Queen Mary University of London, London
- Y. Cai, A.S. Fisher, C. O'Grady, J.M. Thompson, M. Weaver
SLAC, Menlo Park, California
- W. Kozanecki
CEA, Gif-sur-Yvette
- B.F. Viaud
Montreal University, Montreal, Quebec
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We present a novel method to characterize the e ± phase space at the IP of the SLAC B-factory, that combines single-beam measurements with a detailed mapping of luminous-region observables. Transverse spot sizes are determined in the two rings with synchrotron-light monitors & extrapolated to the IP using measured lattice functions. The 3-D luminosity distribution, as well as the spatial dependence of the transverse-boost distribution of the colliding beams, are measured using e+ e- > mu+ mu- events reconstructed in the BaBar tracking detectors; they provide information on the luminous spot size, the e- angular divergence & the vertical emittance. The specific luminosity, which is proportional to the inverse product of the overlap IP beam sizes, is continuously monitored using Bhabha-scattering events. The combination of these measurements provide constraints on the horizontal & vertical spot sizes, angular divergences, emittances & beta functions of both beams at the IP during routine high-luminosity operation. Preliminary results of this combined-spot size analysis are confronted with measurements of IP beta-functions & overlap IP beam sizes at low beam current.
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