A model for the interaction of high-energy particles in straight and bent crystals implemented in Geant4

Abstract

A model for the simulation of orientational effects in straight and bent periodic atomic structures is presented. The continuum potential approximation has been adopted. The model allows the manipulation of particle trajectories by means of straight and bent crystals and the scaling of the cross sections of hadronic and electromagnetic processes for channeled particles. Based on such a model, an extension of the Geant4 toolkit has been developed. The code has been validated against data from channeling experiments carried out at CERN.

Interference in spectrum of radiation from doubly scattered charged particle

“…There are several known crystal-assisted deflection mechanisms: channeling in a bent crystal [24], volume reflection in a bent crystal [25], and mirroring in a straight ultrathin "half-wavelength" crystal [26]. The acceptance to a stable channeling mode in practice may be insufficiently high (see, e.g., [27]), whereas for mirroring in a "half-wavelength" crystal, the relative spread in deflection angles must be sizable due to the impact parameter dependence. Volume reflection is not beset by such deficiencies, so we examine it in the first place.…”

Intense and energetic radiation from crystalline undulators

“…NWT has been discussed previously in the crystal undulator literature, see e.g. [4], but none seem so far to have even sketched a possible scenario where energy consumption, target robustness, etc. are taken into consideration.…”

“…Among the many proposed solutions to obtain modified crystalline lattices are acoustic waves, surface indentations (for example by means of laser ablation [3]), mechanical modification [4] and controlled mixing of elements with different lattice constants such as silicon and germanium [5]. We focus here on the latter approach, usually obtained by adding a linearly increasing (small) fraction of Ge to a Si substrate by use of Molecular Beam Epitaxy (MBE) which strains the lattice in the direction of growth.…”

About multiple scattering of high energy protons in crystal deflectors

“…The model of the lattice of bent atomic strings or planes gives a good agreement with the results of the experiments on the study of channeling and volume reflection in bent crystals performed at the external beams of the CERN SPS and in the experiments on the SPS beam collimation assisted with a bent crystal. In the last years, simulation codes for these purposes were also developed by the other authors [8][9][10][11].…”