Quasi-mosaicity as a powerful tool to investigate coherent effects

Quasi-mosaicity is a mechanical property driven by anisotropy in diamond-like structure crystals such as Si and Ge. QM crystals were recently proposed as optical components of a Laue lens for focusing hard X-rays (with energy larger than 70 keV). In contrast to a Laue lens based on conventional crystals (e.g. mosaic crystals), usage of QM crystals allows focusing the incident beam in a spot smaller than the dimension of the diffracting crystal. Focusing of photons in a small spot would allow an unprecedented resolution and sensitivity, together with a wide-passband response. In astrophysics, a Laue lens implementing QM crystals should allow observations of cosmic phenomena producing X-ray emissions with high sensitivity. As another, a Laue lens would be useful for imaging in nuclear medicine, leading to a lower radioactive dose imparted to the patient because of no need for tomography scanning. Quasi-mosaicity was also used for bending Si crystals in order to steer high-energy particles via coherent effects in crystals, viz. planar channeling and volume reflection. Channeled or reflected light particles are also useful as sources of gamma ray beams with intense flux, which can be either monochromatic or polychromatic.