Gamma Ray Cherenkov-Transition Radiation

The production of gamma-ray Cherenkov-transition radiation (GCTR) by charged particles in the photon energy region 0.8 - 2 MeV is studied theoretically using the results of the recent discovery that in the above mentioned region the dielectric constant or the refraction index of some materials is greater than 1 due to Delbruck scattering on Coulomb field of nuclei. Using the results of the carried out numerical calculations, the possibility of observing GCTR and some of its applications are discussed

Some new processes in the collisions of high energy ions and electrons with amorphous or crystalline target atoms

It is shown that taking into account the energy levels of the ions and/or of the crystalline atoms, some energy transfer and excitation processes with consequences similar to the Kossel and Okorokov effects can take place when some additional resonance conditions are satisfied. Such resonance processes can be expected also when microbunched electron beams interact with ions. Since these processes have significant cross-sections and the interaction of projectile ions with atoms of crystals has not been almost studied, it is proposed to begin their study in Kossel- and Okorokov-type experiments

Non-exciting wakefield structured bunches in a one-dimensional plasma model

A model of one-dimensional (1D) cold plasma with an external train of rigidly structured bunches with diverse charges has been introduced. In this model, a solution that cancels the wakefield after the train is found. The density of such bunches can be much greater than the density of the plasma, and a high amplitude electrical field arising inside the train can be used for charged-particle acceleration. In addition, analytical and numerical simulations have been performed

Superluminal synchrotron radiation

To avoid complex computations based on wide Fourier expansions, the electromagnetic field of synchrotron radiation (SR) was analyzed using Lienard-Wiechert potentials in this work. The retardation equation was solved for ultrarelativistic movement of rotating charge at distances up to the trajectory radius. The radiation field was determined to be constricted into a narrow extended region with transverse sizes approximately the radius of trajectory divided by the particle Lorentz factor (characteristic SR length) cubed in the plane of trajectory and the distance between the observation and radiation emission point divided by the Lorentz factor in the vertical direction. The Lienard-Wiechert field of rotating charge was visualized using a parametric form to derive electric force lines rather than solving a retardation equation. The electromagnetic field of a charging point rotating at superluminal speeds was also investigated. This field, dubbed a superluminal synchrotron radiation (SSR) field by analogy with the case of a circulating relativistic charge, was also presented using a system of electric force lines. It is shown that SSR can arise in accelerators from “spot” of SR runs faster than light by outer wall of circular accelerator vacuum chamber. Furthermore, the mentioned characteristic lengths of SR in orbit plane and in vertical direction are less than the interparticle distances in real bunches in ultrarelativistic accelerators. It is indicating that this phenomenon should be taken into account when calculating bunch fields and involved at least into the beam dynamic consideration

Observation of soft X-ray Cherenkov radiation in Al

The soft X-ray radiation generated by 5.7 MeV electrons from both an Al foil and a Mylar film in forward direction was experimentally studied. A narrow specific directivity, an ultra-narrow spectral bandwidth and a good consistency between the experiment and theory prove that the Cherenkov radiation (CR) with photon energy near the L-edge of absorption in Al was observed. The results demonstrate that the CR spectral-angular properties and the absolute photon yield can be described well enough using Pafomov's theoretical model and Henke's refractive index database, which is essential for all practical applications

Vibrating Wire Scanner/Monitor for Photon Beams with Wide Range of Spectrum and Intensity

Developed vibrating wire scanner showed high sensitivity to the charged particles beamintensity (electron, proton, ions). Since the mechanism of response of frequency shift due to theinteraction with deposited particles is thermal one, the vibrating wire scanner after somemodification can be successfully used also for profiling and positioning of photon beams withwide range of spectrum and intensity. Some new results in this field are presented

Development of New Algorithm in the Method of a Resonant Vibrating Target for Large Scanning Speeds

The work is devoted to the study of scanning the transverse profile of a beam using a vibrating wire. A new algorithm has been developed that allows the use of a resonant vibrating target method for high scanning speeds. The method is based on the idea of measuring secondary/reflected particles/radiation generated from the interaction of the beam particles with the wire material, synchronously with the frequency of the wire oscillation. The proposed algorithm for using a differential signal with sign inversion on consecutive measurements from half-periods of wire oscillations is generalized for the case when the scanning speed is much higher than the average speed of the wire oscillation