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International audienceThis paper is devoted to an experimental study of focusing and defocusing positively charged particle beams with the help of specially bent single crystals. Four crystals have been fabricated for this purpose. The studies have been performed at the CERN SPS in 400  GeV/c proton and 180  GeV/c pion beams. The results of measurements of beam envelopes are presented. The rms size of the horizontal profile at the focus was 5–8 times smaller than at the exit of the crystals. The measured focal lengths were 4–21 m. The results of measurements are in good agreement with calculations. Possible applications of focusing crystals in present and future high energy accelerators are discussed

International audienceA deflection efficiency of about 61% was observed for 400 GeV/c protons due to channeling, most strongly along the 〈110〉 axis of a bent silicon crystal. It is comparable with the deflection efficiency in planar channeling and considerably larger than in the case of the 〈111〉 axis. The measured probability of inelastic nuclear interactions of protons in channeling along the 〈110〉 axis is only about 10% of its amorphous level whereas in channeling along the (110) planes it is about 25% . High efficiency deflection and small beam losses make this axial orientation of a silicon crystal a useful tool for the beam steering of high energy charged particles

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Caliste HD is a recently developed micro-camera designed for X and gamma-ray astronomy, based on a 1×1 cm 2 CdTe Schottky pixelated detector. Its entire surface is composed of 256 pixels, disposed on a 16×16 pixel matrix. This spectrometer is buttable on its 4 sides and can be used to create a large focal plane. Caliste HD is designed for space environment. Its IDeF-X front-end electronics has a low power consumption, excellent noise performance and a wide dynamic range, from 2 keV to 1 MeV. Moreover, electronic noise performances of this device were optimized to set the low level-energy threshold lower than 2 keV. This paper focuses on the Caliste HD performance near the low energy limit. For this purpose, we have exposed the Caliste HD module to a mono-energetic X-ray beam, and set energies between 2 and 12 keV. We measured accurately the detection efficiency in this energy range and found it to be ranging from 39% to 75% for energies from 2.2 keV to 11.6 keV, considering only particles detected in the single-event photopeak and ignoring events impinging between two adjacent pixels. This efficiency detection profile thereby highlights crucial effects of the Pt electrode opacity on Caliste HD low energy response, and suggests the presence of absorption zones at the interface between CdTe crystal and platinum. Respective thickness of each layer were estimated by simulation and confirmed by RBS (Rutherford Backscattering Spectroscopy). Besides, using a mono-energetic beam allows fine energy resolution measurement, which was found to be ranging from 560 to 760 eV FWHM between 2 and 12 keV. In addition, the linearity of this spectrometer and the issue of charge sharing between adjacent pixels were studied. This study revealed that spectroscopic performances remain excellent for such boundary operating conditions.