Notes about collision monochromatization in e+e−e^+e^- colliders

The manuscript describes several monochromatization schemes starting from A.~Renieri \cite{ref:Renieri} proposal for head-on collisions based on correlation between particles transverse position and energy deviation. We briefly explain initial proposal and expand it for crossing angle collisions. Then we discuss new monochromatization scheme for crossing angle collisions based on correlation between particles longitudinal position and energy deviation

Beam-beam effects investigation and parameters optimization for a circular e+e- collider TLEP to study the Higgs boson

Several proposals exist for future circular electron-positron colliders designed for precise measurements of the Higgs boson characteristics and electroweak processes. At very high energies, synchrotron radiation of the particles in a strong electromagnetic field of the oncoming bunch (beamstrahlung) becomes extremely important, because of degradation of the beam lifetime and luminosity. We present theoretical calculations of beamstrahlung (including the beam lifetime reduction and the energy spread increase) which are benchmarked against quasi strong-strong computer simulation. Calculation results are used to optimize TLEP project (CERN).Comment: 17 pages, 2 tables, 9 figure

Dynamic aperture limitation in e+e−e^+e^- colliders due to synchrotron radiation in quadrupoles

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 tracking for LEP and the Future Circular $e^+e^-$ Collider (FCC-ee). Here we describe a new mechanism of instability created by modulation of the particle energy at the double betatron frequency by synchrotron radiation in the quadrupoles. Energy modulation varies transverse focusing strength at the same frequency and creates a parametric resonance of the betatron oscillations with unusual properties. It occurs at arbitrary betatron frequency (the resonant detuning is always zero) and the magnitude of the parameter modulation of the betatron oscillation (strength of the resonance driving term) depends on the oscillation amplitude. Equilibrium between the radiation damping and the resonant excitation gives the boundary of the stable motion. Starting from 6d equations of motion we derive and solve the relevant differential equation describing the resonance, and show good agreement between analytical results and numerical simulation

Effect of the superconducting wiggler on the DELSY beam dynamics

The project DELSY is being under development at JINR, Dubna, Russia. This synchrotron radiation source is dedicated to the investigation on condensed matter physics, atomic physics, biology, medicine, chemistry, micromechanics, lithography and others. The storage ring DELSY is an electron storage ring with the beam energy 1.2 GeV and 4 straight sections to accommodate accelerator equipment and insertion devices. One of the straight sections is intended for a 10 T superconducting wiggler (wavelength shifter) and one for the undulator with 150 periods and a magnetic field of 0.75 T. The wiggler will influence many aspects of beam dynamics: linear motion, dynamic aperture, emittance, damping times etc. The problem is rather serious for the DELSY machine because the energy of the electron beam is small while the wiggler's magnetic field is strong. In this paper we consider two models of the wiggler's magnetic field with and without the focusing caused by the sextupolar field of the wiggler as we need to develop the requirements to the wiggler design. We study the influence of the 10 T wiggler on the beam dynamics in the DELSY storage ring and propose a possible scheme to cure it. The combined work of the insertion device is presented too.Comment: 17 pages, submitted to journal NIM