Elastic and inelastic scattering of 15N ions by 13C nuclei at energy 84 MeV

New experimental data of the 15N + 13C elastic and inelastic scattering were obtained at the energy Elab(15N) = 84 MeV. The data were analyzed within the coupled-reaction-channels method. The elastic and inelastic scattering of nuclei 15N + 13С as well as the more important nucleon and cluster transfer reactions were included in the channels-coupling scheme. The WS potential parameters for the 15N + 13С nuclei interactions in ground and excited states as well as deformation parameters of these nuclei were deduced. The contributions of one- and two-step transfers in the 15N + 13C elastic and inelastic scattering were estimated. The results of the 15N + 13С elastic scattering at the energy Elab(15N) = 84 MeV, obtained in this work, were compared with that of the 15N + 12С elastic scattering at the energy Elab(15N) = 81 MeV.

Initial State Interaction for the 20Ne + 130Te and 18O + 116Sn Systems at 15.3 AMeV from Elastic and Inelastic Scattering Measurements

Double charge exchange (DCE) reactions could provide experimentally driven information about nuclear matrix elements of interest in the context of neutrinoless double-β decay. To achieve this goal, a detailed description of the reaction mechanism is mandatory. This requires the full characterization of the initial and final-state interactions, which are poorly known for many of the projectile-target systems involved in future DCE studies. Among these, we intend to study the 20Ne + 130Te and 18O + 116Sn systems at 15.3 AMeV, which are particularly relevant due to their connection with the 130Te→130Xe and 116Cd→116Sn double-β decays. We measure the elastic and inelastic scattering cross-section angular distributions and compare them with theoretical calculations performed in the optical model, one-step distorted wave Born approximation, and coupled-channel approaches using the São Paulo double-folding optical potential. A good description of the experimental data in the whole explored range of transferred momenta is obtained provided that couplings with the 21+ states of the projectile and target are explicitly included within the coupled-channel approach. These results are relevant also in the analysis of other quasi-elastic reaction channels in these systems, in which the same couplings should be included.

Influence of plasmon excitations on atomic-resolution quantitative 4D scanning transmission electron microscopy

Scanning transmission electron microscopy (STEM) allows to gain quantitative information on the atomic-scale structure and composition of materials, satisfying one of todays major needs in the development of novel nanoscale devices. The aim of this study is to quantify the impact of inelastic, i.e. plasmon excitations (PE), on the angular dependence of STEM intensities and answer the question whether these excitations are responsible for a drastic mismatch between experiments and contemporary image simulations observed at scattering angles below $$\sim $$ ∼ 40 mrad. For the two materials silicon and platinum, the angular dependencies of elastic and inelastic scattering are investigated. We utilize energy filtering in two complementary microscopes, which are representative for the systems used for quantitative STEM, to form position-averaged diffraction patterns as well as atomically resolved 4D STEM data sets for different energy ranges. The resulting five-dimensional data are used to elucidate the distinct features in real and momentum space for different energy losses. We find different angular distributions for the elastic and inelastic scattering, resulting in an increased low-angle intensity ($$\sim $$ ∼ 10–40 mrad). The ratio of inelastic/elastic scattering increases with rising sample thickness, while the general shape of the angular dependency is maintained. Moreover, the ratio increases with the distance to an atomic column in the low-angle regime. Since PE are usually neglected in image simulations, consequently the experimental intensity is underestimated at these angles, which especially affects bright field or low-angle annular dark field imaging. The high-angle regime, however, is unaffected. In addition, we find negligible impact of inelastic scattering on first-moment imaging in momentum-resolved STEM, which is important for STEM techniques to measure internal electric fields in functional nanostructures. To resolve the discrepancies between experiment and simulation, we present an adopted simulation scheme including PE. This study highlights the necessity to take into account PE to achieve quantitative agreement between simulation and experiment. Besides solving the fundamental question of missing physics in established simulations, this finally allows for the quantitative evaluation of low-angle scattering, which contains valuable information about the material investigated.