Electromagnetic field and radiation for a charge moving along a helical trajectory inside a waveguide with dielectric filling

We investigate the electromagnetic field generated by a point charge moving along a helical trajectory inside a circular waveguide with conducting walls filled by homogeneous dielectric. The parts corresponding to the radiation field are separated and the formulae for the radiation intensity are derived for both TE and TM waves. It is shown that the main part of the radiated quanta is emitted in the form of the TE waves. Various limiting cases are considered. The results of the numerical calculations show that the insertion of the waveguide provides an additional mechanism for tuning the characteristics of the emitted radiation by choosing the parameters of the waveguide and filling medium.Comment: 17 pages, 9 figures, discussion, graphs, and references adde

Status of Muon Collider Research and Development and Future Plans

The status of the research on muon colliders is discussed and plans are outlined for future theoretical and experimental studies. Besides continued work on the parameters of a 3-4 and 0.5 TeV center-of-mass (CoM) energy collider, many studies are now concentrating on a machine near 0.1 TeV (CoM) that could be a factory for the s-channel production of Higgs particles. We discuss the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-Z target and proceeding through the phase rotation and decay ($\pi \to \mu \nu_{\mu}$) channel, muon cooling, acceleration, storage in a collider ring and the collider detector. We also present theoretical and experimental R & D plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This report is an update of the progress on the R & D since the Feasibility Study of Muon Colliders presented at the Snowmass'96 Workshop [R. B. Palmer, A. Sessler and A. Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics (Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].Comment: 95 pages, 75 figures. Submitted to Physical Review Special Topics, Accelerators and Beam

Undulator-based production of polarized positrons

Full exploitation of the physics potential of a future International Linear Collider will require the use of polarized electron and positron beams. Experiment E166 at the Stanford Linear Accelerator Center (SLAC) has demonstrated a scheme in which an electron beam passes through a helical undulator to generate photons (whose first-harmonic spectrum extended to 7.9MeV) with circular polarization, which are then converted in a thin target to generate longitudinally polarized positrons and electrons. The experiment was carried out with a one-meter-long, 400-period, pulsed helical undulator in the Final Focus Test Beam (FFTB) operated at 46.6GeV. Measurements of the positron polarization have been performed at five positron energies from 4.5 to 7.5MeV. In addition, the electron polarization has been determined at 6.7MeV, and the effect of operating the undulator with a ferrofluid was also investigated. To compare the measurements with expectations, detailed simulations were made with an upgraded version of Geant4 that includes the dominant polarization-dependent interactions of electrons, positrons, and photons with matter. The measurements agree with calculations, corresponding to 80% polarization for positrons near 6MeV and 90% for electrons near 7MeV.Comment: 64 pages, 63 figure

Muon-Muon and other High Energy Colliders

Parameters are given of 4 TeV and 0.5 TeV (c-of-m) high luminosity muon-muon Colliders. We discuss the various systems, starting from the proton accelerator needed to generate the muons and proceeding through muon cooling, acceleartion and storage in a collider ring. Detector background, polarization are analyzed. We also look at other type of colliders (hadron, lepton and photon-photon) for comparison. Technical problems in obtaining increased energy in each type of machine are presented. Their relative size and probable relative costs are discussed