CasP Express: A Web-Based Platform for Swift Ion-Solid Interaction Visualization

Accurate modeling of ion-solid interactions is fundamental to the advancement of the IBA community. However, accessing state-of-the-art theoretical calculations often requires researchers to navigate complex, computationally heavy codes or compile legacy software. To bridge the gap between rigorous theoretical physics and modern accessibility, we introduce CasP Express, a fast, lightweight, and fully browser-based application designed to compute and visualize swift ion interactions with matter on the fly. Built around the Convolution Approximation for Swift Particles (CasP) parametrization framework, the platform utilizes a modular, client-side JavaScript architecture that eliminates the need for server-side processing. CasP Express centralizes millions of precalculated data points into an intuitive interface, allowing users to instantly evaluate and compare multiple physical phenomena. The application features five core modules: (1) Stopping Cross Sections (SCS), which overlays CasP 6.0 data, analytical Double Konac fittings, SRIM tables, DPASS calculations, and the IAEA experimental database; (2) Charge State Distributions, for gases and solids. Besides the CasP data, the platform offers (3) PIXE Cross Sections, interrogating ISICS-generated libraries (PWBA and ECPSSR) alongside Helmut Paul’s empirical database; (4) Differential scattering cross-sections, computing exact laboratory-frame cross-sections using analytical screened potentials; and (5) Energy Straggling, which implements updated straggling formulas and intra-atomic electron bunching effects. We present this tool as both a powerful analytical resource for experimentalists in the laboratory and an interactive pedagogical platform for the broader IBA community.