Parametrization of the driven betatron oscillation

An AC dipole is a magnet which produces a sinusoidally oscillating dipole field and excites coherent transverse beam oscillations in a synchrotron. By observing this driven coherent oscillation, the linear optical parameters can be directly measured at locations of the beam position monitors. The dr...

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Bibliographic Details
Published in:Physical review special topics. PRST-AB. Accelerators and beams 2008-08, Vol.11 (8), p.084002, Article 084002
Main Authors: Miyamoto, R., Kopp, S. E., Jansson, A., Syphers, M. J.
Format: Article
Language:English
Subjects:
Amplitudes
Beams (radiation)
Dipoles
Free vibration
Parameterization
Parameters
Position measurement
Quadrupoles
Relativistic Heavy Ion Collider
Synchrotrons
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Summary:An AC dipole is a magnet which produces a sinusoidally oscillating dipole field and excites coherent transverse beam oscillations in a synchrotron. By observing this driven coherent oscillation, the linear optical parameters can be directly measured at locations of the beam position monitors. The driven oscillations induced by an AC dipole will generate a phase space ellipse which differs from that of free oscillations. If not properly accounted for, this difference can lead to misinterpretations of the actual optical parameters, for instance, 6% or more in the cases of the Tevatron, RHIC, or LHC. This paper shows that the effect of an AC dipole on the observed linear optics is identical to that of a thin lens quadrupole. By introducing a new amplitude function to describe this new phase space ellipse, the motion produced by an AC dipole becomes easier to interpret. The introduction of this new amplitude function also helps measurements of the normal Courant-Snyder parameters based on beam position data taken under the influence of an AC dipole. This new parametrization of driven oscillations is presented and is used to interpret data taken in the FNAL Tevatron using an AC dipole.
ISSN:1098-4402
1098-4402
2469-9888
DOI:10.1103/PhysRevSTAB.11.084002