[Seminars] Accelerator Science Seminar Today

[Holly Jaffey]

ACCELERATOR SCIENCE SEMINAR TODAY

Monday April 10, 2017
ERC 401
4:15pm

Speaker: Uli Wienands (Argonne National Lab)

Title:   Channeling of Electrons and Positrons at SLAC

Abstract: Channeling effects have been known to occur in crystals for a long time. The effect is being used with bent crystals to deflect high-energy beams for extraction and collimation purposes.  Crystal collimation is in active testing at the LHC and has also been proposed for the ILC. A relative large amount of proton data is available, while high-quality electron data have existed only for low particle energy.
            Since 2013, several key experiments have been performed at SLAC investigating channeling of positrons and electrons in bent crystals, the latter in an energy range from 3 to 20 GeV, using the FACET and the ESTB beam facilities. Using a Ferrara-made bent Si (110) crystal these experiments have measured channeling parameters in a little-explored energy range and have investigated the quasi-channeling oscillations predicted by Sytov et al. Quantitative measurements provide data suitable to benchmark simulations and, e.g., design crystal-based beam collimation systems.  More recently, the experiments have shifted towards studying the gamma-ray emission by high-energy electrons passing through crystals. Crystalline undulator devices have been proposed; some of these suitable for electron beams as well as positron beams.
            The SLAC facilities are presently undergoing changes related to LCLS-II construction. I will end my presentation with an outline of the plans for the new facilities and the crystal program.
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