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ABSTRACT: The six straight insertions of the PEP II High Energy Ring (HER)[1] serve various functions: lattice tuning, beam injection and abort, providing space for rf cavities, longitudinal and transverse feedback, beam diagnostics and the interaction point. A stainless steel vacuum system has been designed; prototypes are currently being built. Cooling is required due to radiation coming from the last arc dipole and resistive losses in the vacuum chamber. Although the nominal beam current of the HER is 1 A the vacuum system is designed for 3 A to provide margin and an upgrade path. I. DESIGN REQUIREMENTS The PEP II Conceptual Design Report (CDR, Ref.[2]) calls for an average pressure in the straights of 3 nTorr, mainly determined by beam lifetime considerations. In order to achieve this pressure, about 3 m pump spacing would be required in the first 6--7 cells of each straight section due to the still significant synchrotron radiation at 3 A current. Initially, lower intensities are expected...
04/1998;
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ABSTRACT: Results are presented of a study of the dipole electromagnetic
fields in a detuned accelerating section which are excited by a
pointlike bunch. The field-matching technique is used for the field
calculations. The transverse coupling impedance, the kick factors, and
the point wake function are found
IEEE Transactions on Microwave Theory and Techniques 07/1995; · 1.85 Impact Factor
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ABSTRACT: Ions produced by a beam on the residual gas induce desorption from the beam pipe wall and may lead to a runaway pressure build up. The main mechanism of ion production is usually inelastic collisions of the beam particles. It may not be true for PEP-II where the combination of high energy and high beam current leads to MWs of the total power in synchrotron radiation. The photoeffect on the residual gas may produce more ions than produced in the inelastic collisions due to a much larger cross-section of the photoeffect at low photon energies where the number of photons is maximum
Particle Accelerator Conference, 1995., Proceedings of the 1995; 06/1995
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ABSTRACT: Results are presented of a study of the dipole EM fields in
detuned accelerating sections excited by a point-like bunch. The
transverse coupling impedance, the kick factors, and the wake functions
are found
Particle Accelerator Conference, 1995., Proceedings of the 1995; 06/1995
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ABSTRACT: A perturbation method is used to obtain analytic expressions for
the multipole longitudinal and transverse beam impedance for an
arbitrary waveguide whose radius is slowly varying and for the specific
case of a symmetric small-angle taper. This method is also applicable
for a particle in a wiggler undergoing periodic motion
Particle Accelerator Conference, 1995., Proceedings of the 1995; 06/1995
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U. Wienands,
E. Daly, S.A. Heifets,
A. Kulikov,
N. Kurita,
M. Nordby,
C. Perkins,
E. Reuter,
J.T. Seeman,
F.C. Belser,
J. Berg,
F.R. Holdener,
J.A. Kerns,
M.R. McDaniel,
W. Stoeffl
[show abstract]
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ABSTRACT: The six straight insertions of the PEP II High Energy Ring (HER)
serve various functions: lattice tuning, beam injection and abort,
providing space for RF cavities, longitudinal and transverse feedback,
beam diagnostics and the interaction point. A stainless steel vacuum
system has been designed; prototypes are currently being built. Cooling
is required due to radiation coming from the last arc dipole and
resistive losses in the vacuum chamber. Although the nominal beam
current of the HER is 1 A the vacuum system is designed for 3 A to
provide margin and an upgrade path
Particle Accelerator Conference, 1995., Proceedings of the 1995; 06/1995
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ABSTRACT: The propagation of the electromagnetic wave in an aperiodic
disk-loaded accelerating section has been studied using the
field-matching technique. A matrix formalism similar to that of the
scattering theory is applied. The method developed allows study of an
arbitrary number of irises and radial space harmonics. Reflection and
transmission coefficients of the structure, its wave and coupling
impedances, beam loading, and other characteristics have been calculated
as a function of the wave frequency. The modifications of the reflection
coefficient by couplers have also been studied. The results of
calculations for the detuned accelerating structure designed as SLAC for
the Next Linear Collider, and consisting of over 200 cells, are given as
an example
IEEE Transactions on Microwave Theory and Techniques 02/1994; · 1.85 Impact Factor
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ABSTRACT: A systematic review of theoretical results for the longitudinal and transverse impedances obtained by different methods is presented. The paper comprises definitions, general theorems, modal analysis, a diffraction model, and analytical results. Several new results are included. In particular, necessary and sufficient conditions are given for the independence of the impedance from the beam longitudinal direction. The impedances of two basic simple structures—that of a cavity and that of a step—are studied in detail. The transition from the regime of a cavity to the regime of a step is explained, an approximate formula describing this transition is given, and the criterion for determining the applicability of each regime is established. The asymptotic behavior of the impedance for a finite number M of periodically arranged cavities as a function of M is studied. The different behaviors of the impedance for a single cavity and that for an infinite number of cavities are explained as resulting from the interference of the diffracted waves. A criterion for determining the transition in the impedance behavior from small M to large M is presented.
AIP Conference Proceedings. 03/1992; 249(1):150-235.
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ABSTRACT: A consistent set of parameters is given for a B‐factory based on collisions of an electron beam from a SRF linac with the positron beam in a storage ring. An optimized lattice, an impedance estimate, a study of beam stability, and a discussion of collisions with large disruption parameters are included.
AIP Conference Proceedings. 10/1990; 214(1):484-507.
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ABSTRACT: Collisions between a weak electron bunch and a strong positron bunch are studied within a flat-beam model. Electrons are tracked through the transverse space-charge field of the positron bunch, and it is shown that positrons in a storage ring may remain stable after asymmetric collisions with a weak electron bunch in spite of large values of the electron disruption parameter. The plasma oscillations that affect collisions with large disruption parameters may be suppressed by properly matching the electrons.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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S Kuhlman,
C E Adolphsen,
R Aiello,
M. Akemoto,
R. Alley,
R W Assmann,
Howard W Baer,
C Baltay,
Karl Leopold Freitag Bane,
B Barakat, [......],
M Woods,
J. Wudka,
J S Wurtele,
M Xie,
Y.T. Yan,
A D Yeremian,
K. Yokoya,
S S Yu,
A.A. Zholents,
Frank Zimmermann
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ABSTRACT: We present the current expectations for the design and physics program of an e+e- linear collider of center of mass energy 500 GeV -- 1 TeV. We review the experiments that would be carried out at this facility and demonstrate its key role in exploring physics beyond the Standard Model over the full range of theoretical possibilities. We then show the feasibility of constructing this machine, by reviewing the current status of linear collider technology and by presenting a precis of our `zeroth- order' design.
