Search

At the Beam Test Facility of the DA{\Phi}NE accelerator complex at the Laboratori Nazionali di Frascati of INFN, 450 MeV positrons have bean deflected, for the first time at sub-GeV energy, using the Planar Channeling process in a bent silicon crystal. The deflection angle obtained is beyond 1 mrad with an high efficiency of deflection. This interesting result finds several applications for manipulation of this kind of beams, in particular for slow extraction from leptons circular accelerators like DA{\Phi}NE. In this work the experimental apparatus, the measurement procedure and the experimental results are reported.

Using the newly developed 530 MeV positron beam from the Mainz Microtron MAMI and employing a bent silicon crystal, we demonstrate the first successful manipulation with high efficiencies of the trajectories of positrons through planar channeling and volume reflection. This uncovered the presence of fine structure within the angular distribution of charged particles when they are channeled between the planes of bent crystals. The alignment of our experimental findings with simulation results not only demonstrates a deeper understanding of the interactions between charged particle beams and bent crystals but also signals a new phase in the development of innovative methodologies for slow extraction in circular accelerators operating in the GeV range, with implications for worldwide accelerators. Our results also mark a considerable progression in the generation of advanced x-ray sources through the channeling process in periodically bent crystals, rooted in a comprehensive understanding of the interactions between positron beams and such crystals.

We present a combined experimental and numerical study of the spin-wave dispersion in NiFe artificial spin-ice (ASI) system consisting of an array of stadium-shaped nanoislands deposited on the top of a continuous NiFe film with nonmagnetic spacer layers of varying thickness. The spin-wave dispersion, measured by wavevector resolved Brillouin light scattering spectroscopy in the Damon-Eshbach configuration, consists of a rich number of modes, with either stationary or propagating character. We find that the lowest frequency mode displays a bandwidth of approximately 0.5 GHz, which is independent of the presence of the film underneath. On the contrary, the BLS intensity of some of the detected modes strongly depends on the presence of the extended thin-film underlayer. Micromagnetic simulations unveil the details of the dynamic coupling between ASI lattice and film underlayer. Interestingly, the ASI lattice facilitates dynamics of the film either specific wavelengths or intensity modulation peculiar to the modes of the ASI elements imprinted in the film. Our results demonstrate that propagating spin waves can be modulated at the nanometer length scale by harnessing the dynamic mode coupling in the vertical, i.e., the out-of-plane direction of suitably designed magnonic structures.