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Abstracts Brochure - CERN

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WEPCH — Poster Session 28-Jun-06 16:00 - 18:00<br />

Linear and Nonlinear Coupling Using Decoupling Transformations<br />

Linear coupling in a storage ring is conveniently<br />

analyzed in terms of transformations A. Wolski, A. Sessler (LBNL)<br />

that put the single-turn map into block-diagonal<br />

form. Such a transformation allows us to define new variables, in which the dynamics are uncoupled. Thus, for<br />

example, the symplectic conditions are simply that the phase area in each of the uncoupled variables is preserved. In<br />

principle, a similar approach may be taken to nonlinear coupling; we discuss such an approach in this paper, giving<br />

some simple illustrations of the ideas, based on the well-known techniques of normal form analysis. We also discuss<br />

some obstacles to finding a nonlinear decoupling transformation in the general case.<br />

SABER Optical Design<br />

SABER, the South Arc Beam Experimental<br />

Region, is a proposed new beam line facility R.A. Erickson, K.L.F. Bane, Y. Nosochkov (SLAC)<br />

designed to replace the Final Focus Test Beam<br />

at SLAC. In this paper, we outline the optical design features and beam parameters now envisioned for SABER. A<br />

magnetic chicane to compress positron bunches for SABER and a bypass line that could transport electrons or positrons<br />

from the two-thirds point of the linac to SABER, bypassing the LCLS systems, are also discussed.<br />

Precision Measurement and Improvement of Optics for e+, e − Storage Rings<br />

Through horizontal and vertical excitations,<br />

we have been able to make a precision mea- Y.T. Yan, Y. Cai (SLAC)<br />

surement of linear geometric optics parameters<br />

with a Model-Independent Analysis (MIA). We have also been able to build up a computer model that matches<br />

the real accelerator in linear geometric optics with an SVD-enhanced Least-square fitting process. Recently, with the<br />

addition of longitudinal excitation, we are able to build up a computer virtual machine that matches the real accelerators<br />

in linear optics including dispersion without additional fitting variables. With this optics-matched virtual<br />

machine, we are able to find solutions that make changes of many normal and skew quadrupoles for machine optics<br />

improvement. It has made major contributions to improve PEP-II optics and luminosity. Examples from application<br />

to PEP-II machines will be presented.<br />

Measurements and Modeling of Eddy Current Effects in BNL’s AGS Booster<br />

Recent beam experiments at BNL’s AGS<br />

Booster have enabled us to study in more<br />

detail the effects of eddy currents on the lattice<br />

structure and our control over the basic<br />

K.A. Brown, L. Ahrens, C.J. Gardner, J. Glenn, M. Harvey, W. Meng,<br />

K. Zeno (BNL)<br />

lattice parameters of betatron tune and chromaticity. The Booster is capable of operating at ramp rates as high as 8<br />

T/sec. At these ramp rates eddy currents in the vacuum chambers have significant effects on the fields and gradients<br />

seen by the beam as it is accelerated. The Booster was designed with these effects in mind and to help control the<br />

field uniformity and linearity in the Booster Dipoles special vacuum chambers were designed with current windings<br />

289<br />

WEPCH060<br />

WEPCH061<br />

WEPCH062<br />

WEPCH063

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