Negative Particle Planar and Axial Channeling and Channeling Collimation

Abstract

While information exists on high energy negative particle channeling there has been little study of the challenges of negative particle bending and channeling collimation. Partly this is because negative dechanneling lengths are relatively much shorter. Electrons are not particularly useful for investigating negative particle channeling effects because their material interactions are dominated by channeling radiation. Another important factor is that the current central challenge in channeling collimation is the proton-proton Large Hadron Collider (LHC) where both beams are positive. On the other hand in the future the collimation question might reemerge for electron-positron or muon colliders. Dechanneling lengths increase at higher energies so that part of the negative particle experimental challenge diminishes. In the article different approaches to determining negative dechanneling lengths are reviewed. The more complicated case for axial channeling is also discussed. Muon channeling as a tool to investigate dechanneling is also discussed. While it is now possible to study muon channeling it will probably not illuminate the study of negative dechanneling.

Channeling and Radiation in Periodically Bent Crystals

“…6 Figure 6.9 clearly demonstrates that further theoretical and experimental investigations of the electron channeling are needed (see also the review [80]). Additional line of reasoning, based on the concept of rechanneling process, is presented in Sect.…”

“…5.4). Our estimates [74,80] show that the brilliance of the CUL radiation can be as large as 10 28 -10 32 photons/s/mrad 2 /mm 2 /0.1 % BW in the photon energy range ω = 10 5 -10 6 eV (the corresponding wavelengths are 0.01-0.1 Å), see Fig. In this case, the waves emitted by different particles have approximately the same phase, so that the intensity of radiation becomes proportional to the beam density squared.…”

Relaxation of axially confined 400 GeV/c protons to planar channeling in a bent crystal

“…[14,15], no other data collected with short crystals suitable for applications are available in the literature. As pointed out in [18], there is a need for deeper understanding about axial channeling for its exploitation in beam manipulation.…”

Electron channeling experiments with bent silicon single crystals—a reanalysis based on a modified Fokker-Planck equation

“…The electron distribution in the channeling planes has been neglected. Without loss of generality it can be assumed that only the potential in one period, indicated by the vertical dashed lines in figure 1, must be considered for the calculations of the drift coefficient D (1) drift…”

“…The phenomenon of channeling of positively and negatively charged particles plays an important role in the high energy physics domain like for beam bending and collimation [1]. Another intriguing field of research is the development of crystalline undulators for intense radiation production with energies of 100 keV or higher employing relativistic positrons or electrons with energies in the order of a few hundred MeV or more.…”