We present the experimental data and analysis of experiments conducted at SLAC National Accelerator\ud Laboratory investigating the processes of channeling, volume-reflection and volume-capture along the\ud (111) plane in a strongly bent quasimosaic silicon crystal. These phenomena were investigated at 5\ud energies: 3.35, 4.2, 6.3, 10.5, and 14.0 GeV with a crystal with bending radius of 0.15 m, corresponding to\ud curvatures of 0.053, 0.066, 0.099, 0.16, and 0.22 times the critical curvature, respectively. Based on the\ud parameters of fitting functions we have extracted important parameters describing the channeling process\ud such as the dechanneling length, the angle of volume reflection, the surface transmission, and the widths of\ud the distribution of channeled particles parallel and orthogonal to the plane

We report on an experiment performing channeling and volume reflection of a high-energy electron beam using a quasimosaic, bent silicon (111) crystal at the End Station A Test Beam at SLAC. The experiment uses beams of 3.35 and 6.3 GeV. In the channeling orientation, deflections of the beam of 400 μrad for both energies with about 22% efficiency are observed, while in the volume-reflection orientation, deflection of the beam by 120 μrad at 3.35 GeV and by 80 μrad at 6.3 GeV is observed with 86%-95% efficiency. Quantitative measurements of the channeling efficiency, surface transmission, and dechanneling length are taken. These are the first quantitative measurements of channeling and volume reflection using a primary beam of multi-GeV electrons.

The radiation emitted by 855 MeV electrons via planar channeling and volume reflection in a 30.5-μm-thick bent Si crystal has been investigated at the MAMI (Mainzer Mikrotron) accelerator. The spectral intensity was much more intense than for an equivalent amorphous material, and peaked in the MeV range in the case of channeling radiation. Differently from a straight crystal, also for an incidence angle larger than the Lindhard angle, the spectral intensity remains nearly as high as for channeling. This is due to volume reflection, for which the intensity remains high at a large incidence angle over the whole angular acceptance, which is equal to the bending angle of the crystal. Monte Carlo simulations demonstrated that incoherent scattering significantly influences both the radiation spectrum and intensity, either for channeling or volume reflection. In the latter case, it has been shown that incoherent scattering increases the radiation intensity due to the contribution of volume-captured particles. As a consequence, the experimental spectrum becomes a mixture of channeling and pure volume reflection radiations. These results allow a better understanding of the radiation emitted by electrons subjected to coherent interactions in bent crystals within a still-unexplored energy range, which is relevant for possible applications for innovative and compact x-ray or γ-ray sources

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