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Turn-by-Turn Imaging of the Transverse Beam Profile in PEP-II

Fisher, Alan S. and Petree, Mark and Kraus, Richard and Au, Yat-Shan and Chan, Benny (2006) Turn-by-Turn Imaging of the Transverse Beam Profile in PEP-II. In: BEAM INSTRUMENTATION WORKSHOP 2006: Twelfth Beam Instrumentation Workshop, Batavia, Illinois (USA), 1-4 May 2006. AIP Conference Proceedings. No.868. American Institute of Physics , Melville, NY, pp. 303-312. ISBN 978-0-7354-0369-7.

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During injection or instability, the transverse profile of an individual bunch in a storage ring can change significantly in a few turns. However, most synchrotron-light imaging techniques are not designed for this time scale. We have developed a novel diagnostic that enhances the utility of a fast gated camera by adding, inexpensively, some features of a dual-axis streak camera, in order to watch the turn-by-turn evolution of the transverse profile, in both x and y. The beam's elliptical profile is reshaped using cylindrical lenses to form a tall and narrow ellipse—essentially the projection of the full ellipse onto one transverse axis. We do this projection twice, by splitting the beam into two paths at different heights, and rotating the ellipse by 90° on one path. A rapidly rotating mirror scans these vertical “pencils” of light horizontally across the photocathode of the camera, which is gated for 3 ns on every Nth ring turn. A single readout of the camera captures 100 images, looking like a stroboscopic photograph of a moving object. We have observed the capture of injected charge into a bunch and the rapid change of beam size at the onset of a fast instability.

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Additional Information:© 2006 American Institute of Physics. Students participated in this project with support from summer programs of the U.S. Department of Energy and SLAC (Summer Undergraduate Laboratory Internships, for R.K.), and of Caltech (Summer Undergraduate Research Fellowships, for Y.-S.A. and B.C.). Prof. Frank Porter of Caltech provided support for the initial experiments. We appreciate the support of PEP’s accelerator-physics and operations groups.
Funding AgencyGrant Number
Department of Energy (DOE)UNSPECIFIED
Stanford Linear Accelerator CenterUNSPECIFIED
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Subject Keywords:particle beam diagnostics; photography; streak cameras; storage rings
Series Name:AIP Conference Proceedings
Issue or Number:868
Record Number:CaltechAUTHORS:FISaipcp06
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6424
Deposited By: Archive Administrator
Deposited On:08 Dec 2006
Last Modified:08 Nov 2021 20:33

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