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The beam-beam effects of the PEP-II as an asymmetric collider are studied with strong-strong simulations using a newly developed particle-in-cell (PIC) code. The simulated luminosity agrees with the measured one within 10% in a large range…
We first introduce the design parameters of the Beijing Electron-Positron Collider II (BEPCII) and the simulation study of beam-beam effects during the design process of the machine. The main advances since 2007 are briefly introduced and…
The successful commissioning and operation of the PEP-II asymmetric e+e- collider motivated further studies to increase luminosity. In this paper, we discuss a modification of the PEP-II lattice to reduce the vertical beta function at the…
The leading Lie generators, including the chromatic effects, due to hard-edge fringe field of single multipole and solenoid are derived from the vector potentials within a Hamiltonian system. These nonlinear generators are applied to the…
The measurement of the betatron tunes in a circular accelerator is of paramount importance due to their impact on beam dynamics. The resolution of the these measurements, when using turn by turn (TbT) data from beam position monitors…
The PEP-II interaction region is designed to accommodate asymmetric beam energies, head-on collisions, small bunch spacing and provide low beta* for high luminosity. Local correction schemes are implemented to compensate non-linear…
The PEP-II luminosity upgrade foreseen for the next years requires an increased number of bunches and lower beta-y* with minor modifications to the present Interaction Region (IR2). When increasing the collision frequency the beams…
A method to estimate linear chromaticity, RMS energy spread, and chromatic beta-beating, directly from turn-by-turn beam position data in a circular electron accelerator, is presented. This technique is based on frequency analysis of a…
A blowup of vertical emittance has been observed in particle tracking simulations with beam-beam and lattice misalignments. It was somewhat unexpected, since estimation without lattice errors did not predict such a blowup unless a residual…
In the framework of the LHC Injectors Upgrade project, the CERN Proton Synchrotron underwent hardware changes during the Long Shutdown 2. These changes required an update of the CERN Proton Synchrotron impedance model and an assessment of…
A high-level beam background is a crucial challenge to future upgrades to the BEPCII collider. We report on the first separate measurement of the main beam background components at BEPCII. The separation measurement enables the beam…
High-index dielectric subwavelength structures and metasurfaces are capable of enhancing light-matter interaction by orders of magnitude via geometry-dependent optical resonances. This enhancement, however, comes with a fundamental…
The PEP-N experiment requires a fast on-line luminosity monitor of modest accuracy plus an off-line method of determining integrated luminosity with accuracy of 0.01 for each pb$^{-1}$. We propose the PEP-2 monitor, based on observing…
In a lepton storage ring of very high energy (e.g. in the $e^+e^-$ Higgs factory) synchrotron radiation from quadrupoles constrains transverse dynamic aperture even in the absence of any magnetic nonlinearities. This was observed in…
Physically speaking, the delta function like beam-beam nonlinear forces at interaction points (IPs) act as a sum of delta function nonlinear multipoles. By applying the general theory established in ref. 1, in this paper we investigate…
The DAFNE-II project is considered now as a possible candidate for upgrading the DAFNE electron-positron collider and improving its luminosity. 6D simulation of the DAFNE-II dynamic aperture under various assumptions (weak and strong RF…
Both horizontal and vertical coherent beam-beam instability are important issues at CEPC. The horizontal instability (X-Z instability) could be induced by beam-beam itself. In this paper we try to study the effect of chromaticity and…
We present an improved system for orbit and betatron phase measurement utilizing nonlinear models of BPM pickup response. We first describe the calculation of the BPM pickup signals as nonlinear functions of beam position using Green's…
Optical gain is a critical process in today's semiconductor technology and it is most often achieved via stimulated emission. In this theoretical study, we find a resonant TE mode in biased low-symmetry two-dimensional metallic systems…
Modern fourth-generation storage ring light sources predominantly utilize digital I/Q-based proportional-integral (PI) feedback for their radio-frequency (RF) systems. This paper introduces a dedicated PI feedback model implemented in the…