Simulation of beam steering phenomena in bent crystals

The simulation methods for the channeling phenomena in GeV/TeV energy range in ideal or distorted crystal lattices are discussed. Monte Carlo predictions for feed-out and feed-in rates, dislocation dechanneling, and deflection efficiencies of bent crystals are compared to the experimental data. The role of multiple interactions with crystal in circular accelerators ("multipass channeling") for the efficiency boost in the crystal-aided extraction experiments is analysed. Possible future applications of the crystal channeling technique are considered.Comment: 10pp. Presented at COSIRES 1998 (Okayama

The theory of the scattering-induced feeding-in in bent crystals

An analytical theory for the efficiency of scattering-induced transitions from a random to a channeled state (feed-in) in bent crystals is derived. The predictions from the theory are in good agreement with experiment and Monte Carlo simulations.Comment: 6 page

The limits of volume reflection in bent crystals

We show that theory predictions for volume reflection in bent crystals agree with recent experimental data. This makes possible to predict volume reflection angle and efficiency in a broad range of energy for various crystals. A simple formula is proposed for volume reflection efficiency. We derive the physical limits for application of crystal reflection at high-energy accelerators where it may help beam collimation.Comment: 6 pages, 2 figure

Optimization of crystal extraction experiment

Using a computer model for the crystal extraction, we investigate the bent-crystal parameters optimal for the extraction experiment. The optimal crystal curvature is found to be near 1 GeV/cm (for pv/R), i.e. a factor of 2--3 higher than for the crystal application in beam lines. An influence of the accelerator optics on extraction is discussed. A possibility of using the high-Z crystals for extraction is considered. The simulations for the ongoing experiments at the CERN-SPS and the Fermilab Tevatron, and for the proposed extraction at LHC, are presented.Comment: 11 pages, 4 figure

Studies of Nanotube Channeling for Efficient Beam Scraping at Accelerators

While particle beam steering (and in particular, "scraping") in accelerators by bent channeling crystals is an established technique extensively tested at IHEP Protvino and other major high-energy labs, an interesting question is how one could improve channeling capabilities by applying modern nanotechnology. Theoretical research of nanotube channeling was in progress over recent years. In this work, we assess potential benefits from nanotube channeling for real accelerator systems. We report simulation studies of channeling in nanostructured material (carbon SWNT and MWNT) tested for possible serving as a primary scraper for the collimation systems of hadron colliders. The advantages of nanostructured material as a potential choice for a primary scraper in a high-energy accelerator such as LHC or the Tevatron are discussed in comparison to crystal lattices and amorphous material. We evaluate physical processes relevant to this application and reveal nanotechnology requirements.Comment: Presented at the Int. Conf. on Atomic Collisions with Solids (ICACS-21, Genova 4-9 July 2004