Polynomial approximation to universal ionisation cross‐sections of K and L shells induced by H and He ion beams

Abstract

In 1970s, Basbas et al.(Phys. Rev. A 1973, 7, 983; Phys. Rev. A 1978, 17, 1655) rose the possibility that PWBA ionisation crosssections could be expressed in terms of a universal ionisation cross-section. Starting from ECPSSR ionisation cross-sections and reproducing Basbas approach, a universal curve can be displayed against the reduced ion velocity, but data are too widespread to allow for a proper polynomial fit. In the present work, Basbas approach was revised and plotted against a rescaled, reduced ion velocity, eliminating most of the data spread and generating in practice a universal ionisation cross-section curve. In this revised approach, the screening parameter, θ n,o , assumes a major role in reaching the universal behaviour. Polynomial approximations are then made to the universal curves for incident H + and He 2+ ions. Cross-sections were then calculated using the polynomial approximations for target elements with atomic number from 11 to 92 and for ion beam energies from 50 keV to 10 MeV, for K-and L-shell ionisation cross-sections and are compared to experimental data from literature. Finally, X-ray yields were simulated for various thick target samples using these polynomial approximations and the outcomes are compared to data obtained at the ITN PIXE set-up.

Comparison of experimental proton-induced fluorescence spectra for a selection of thin high-Z samples with Geant4 Monte Carlo simulations

“…It encompasses the empirical set developed by Paul, Sacher and Bolik [15,16] for K shells for incident protons and alphas, and the empirical set developed by Orlic, Saw and Tang [17,18] for L shells for incident protons. The second set of cross sections, the so-called ''ECPSSR_FormF actor'' set, is based on a polynomial approximation to universal ionisation cross sections of K, L and a selection of M shells calculated from the ECPSSR theory for incident proton and alpha beams; it was recently developed by Taborda and colleagues and it is described in detail in [19,20]. This set covers the 0.1-100 MeV range for K and L shells, and the 0.1-10 MeV range for M shells.…”

Simulation of Auger electron emission from nanometer-size gold targets using the Geant4 Monte Carlo simulation toolkit

“…In the photon simulations, the G4EmLivermorePhysics electromagnetic physics constructor, which is based on the Livermore set of data libraries (EEDL, EPDL and EADL [9]), was utilized. As for the proton simulations, the shell ionization cross-section models from A. Taborda et al [10,11] for K-, L-, and M-shells, otherwise known as the ''EC PSSR_FormFactor" models [6], were used. Both simulation sets disabled all secondary production thresholds to ensure the full simulation of the atomic deexcitation cascades and implemented a maximum step size of 1 nm.…”

Ion beam analysis of Cu(In,Ga)Se 2 thin film solar cells

“…At both alpha beam energies the RBS calibration factor was in agreement within 5 % relative. This same chargesolid angle product was used to simulate the PIXE spectra (using alpha induced ionization cross sections from [27]) for the same structure and assuming a detector efficiency equal to 1 (taking into account the different live times). In this way an energy dependent calibration factor was determined for the PIXE measurements.…”