Channeling experiments at planar diamond and silicon single crystals with electrons from the Mainz Microtron MAMI

Abstract

Line structures were observed for (110) planar channeling of electrons in a diamond single crystal even at a beam energy of 180 MeV . This observation motivated us to initiate dechanneling length measurements as function of the beam energy since the occupation of quantum states in the channeling potential is expected to enhance the dechanneling length. High energy loss signals, generated as a result of emission of a bremsstrahlung photon with about half the beam energy at channeling of 450 and 855 MeV electrons, were measured as function of the crystal thickness. The analysis required additional assumptions which were extracted from the numerical solution of the Fokker-Planck equation. Preliminary results for diamond are presented. In addition, we reanalyzed dechanneling length measurements at silicon single crystals performed previously at the Mainz Microtron MAMI at beam energies between 195 and 855 MeV from which we conclude that the quality of our experimental data set is not sufficient to derive definite conclusions on the dechanneling length. Our experimental results are below the predictions of the Fokker-Planck equation and somewhat above the results of simulation calculations of A. V. Korol and A. V. Solov'yov et al. on the basis of the MBN Explorer simulation package. We somehow conservatively conclude that the prediction of the asymptotic dechanneling length on the basis of the Fokker-Planck equation represents an upper limit.

Nondipolarity of axial channeling radiation at GeV beam energies

“…Refs. [25][26][27]) were unavailable up to now. Since dechanneling affects absolute values, the effect of nondipolarity of CR should principally hold.…”

“…[25] (see also Refs. [26,27]) but first already applied for the simulation of positron production in a hybrid scheme in Ref. [28].…”

MBN explorer atomistic simulations of 855 MeV electron propagation and radiation emission in oriented silicon bent crystal: theory versus experiment

“…A number of simulations have been performed for electrons and positrons of the sub-GeV and GeV energies channeling in straight, bent and periodically bent silicon, diamond and tungsten crystals [40,[48][49][50][51][52][53][54][55] including comparison and benchmarking against experimental data [39,[55][56][57][58].…”

Channeling of electrons and positrons in straight and periodically bent diamond(110) crystals

“…One of the result from the channeling experiments with PBC is the radiation spectra [31]. A particle, channeled in a PBC, undergoes two types of quasi-periodic motion: the channeling oscillations and due to periodicity of the bending.…”