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[1]. The simulated luminosity agrees with the measured one within 10% in a large range of the beam currents. The spectra of coherent dipole oscillation are simulated with and without the transparency symmetry. The simulated tune shift of the...

We studied the electrostatic fields due to the longitudinal and transverse perturbations of a charged particle beam with a uniform distribution propagating inside an rf-shielding cage constructed from evenlyspaced conducting wires. The beam and the rf-cage are surrounded by a concentric conducting beam pipe. Simple formulae are derived for estimating the spacecharge impedances. Numerical exampl...

We explore the intuitive lensing picture of laser-heated nanoparticles occurring in single particle photothermal (PT) microscopy. The effective focal length of the thermal lens (TL) is derived from a ray-optics treatment and used to transform the probing focused Gaussian beam with ABCD Gaussian matrix optics. The relative PT signal is obtained from the relative beam-waist change far from the TL...

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Cornell’s proposed dark photon search (EAGER) requires a high-intensity positron source to generate statistically significant results. One available option is direct extraction of these positrons from the Cornell Synchrotron, which provides a potential 10 positrons per cycle, at 60 cycles per second. This corresponds to a time-averaged current of about 1 nA. However, single-turn extraction of t...

We review the present understanding of beam halo in proton linacs. Space-charge forces acting in mismatched beams have been identified as a major cause of beamhalo. We introduce a new description of the halo using the ratio of moments of the distribution of beam coordinates. We describe the beam-halo experiment that is in preparation at Los Alamos, which will address questions about the beam pr...

The HESR will be optimized to satisfy high beam quality requirements, i.e. Δp/p ∼ 10−5 for the envisaged high antiproton currents. Cold beams react very sensitive to external perturbations and the possible heating of the beam due to them. In this work the perturbation of the beam due to the influence of the electron cooler acting as a non-linear lens and intra-beam scattering (IBS) are the subj...