Whether a string has rotation and shear can be investigated by an anology with a congruence of point particles. Rotation and shear involve first covariant spacetime derivatives of a vector field and, because the metric stress tensor for both the point particle and the string have no such derivatives, the best vector fields can be identified by requiring the conservation of metric stress. It is ...

In this paper we discuss plasma accelerators which might provide high gradient accelerating fields suitable for TeV linear colliders. In particular we discuss two types of plasma accelerators which have been proposed, the Plasma Beat Wave Accelerator and the Plasma Wake Field Accelerator. We show that the electric fields in the plasma for both schemes are very similar, and thus the dynamics of ...

Recently, there has been some interest in planar or rectangular dielectric accelerating structures for future high-gradient linear accelerators. In this paper, we present a detailed analysis of the modes of a dielectric-loaded rectangular waveguide accelerating structure based on a circuit model approximation and mode matching method. In general, the acceleration field in a synchronous accelera...

The ghost-free theory of massive gravity has exact solutions where the effective stress energy generated by the graviton mass term is a cosmological constant for any isotropic metric. Since they are exact, these solutions mimic a cosmological constant in the presence of any matter-induced isotropic metric perturbation. In the Stückelberg formulation, this stress energy is carried entirely by th...

Accurate simulations of various physical processes on digital computers requires huge computing performance, therefore accelerating these scientific and engineering applications has a great importance. Density of programmable logic devices doubles in every 18 months according to Moore’s Law. On the recent devices around one hundred double precision floating-point adders and multipliers can be i...

The common way to produce the accelerating electromagnetic fields in cyclic accelerators is to excite standing waves in accelerating cavities. The mathematical model for these high frequency electromagnetic fields is the eigenvalue problem solving the Maxwell equations in a bounded volume [1]. Usually, the eigenfield corresponding to the fundamental mode of the cavity is used as the acceleratin...

Resonance far-field structures capable to provide high gradient continuos acceleration at millimeter and micron wavelengths are considered. Among such structures are periodically striped open waveguide and oversized waveguide having periodic small perturbations. Main parameters of the structure composed by flat mirrors are estimated on the base of rigorous analytical solution for the eigenmodes...

Next generation of linear accelerators will have multimegawatt rf systems. The RF system of the Next-Linear Collider (NLC) will have hundreds of waveguide components and high-gradient accelerating structures. Waveguide components should reliably handle up to 600 MW of a 400 ns, 11.424 GHz rf pulse [1]. RF breakdown at such high power could damage these components. For example, breakdown damage ...

The spatial resolution of high-accuracy microchannel plate ~MCP! detectors has reached the values, where the so-called detector walk ~or image blurring! may start to limit any further improvements. Image blurring with gain is studied in detail for detectors incorporating angular-biased MCPs. It was found that the presence of the pore bias at the output MCP results in a variation of the charge f...