How do Uncertainties in Atomic Parameters Influence Theoretical Predictions of X-Ray Production Cross Sections By Proton Impact?

J Miranda J Miranda

doi:10.15415/jnp.2020.72007

Abstract

The emission of characteristic X-rays induced by proton impact is a phenomenon known since the first half of the 20th century. Its more widely known application is the analytical technique Particle Induced X-ray Emission (PIXE). Several models have been developed to calculate, first, ionization cross sections and then the subsequent X-ray production cross sections. However, to carry out the comparisons of these predictions with experimental data it is necessary to use atomic parameters databases (fluorescence yields, Coster-Kronig transition probabilities, emission rates) that also have experimental uncertainties. In this work it is demonstrated how these values do not allow to decide which model describes more accurately the cross sections, due to a final “theoretical uncertainty” obtained through the propagation of the original uncertainties.

Highlights

Particle Induced X-ray Emission (PIXE) is a powerful analytical technique [1], which requires a reliable knowledge of ionization cross sections by charged particle impact and the subsequent process of characteristic X-ray emission, including the atomic parameters involved, such as fluorescence yields, Coster-Kronig transition probabilities, and relative emission rates [2]
Since the first half of the 20th century, hundreds of papers regarding the measurement of X-ray production cross sections (XRPCS) and derived ionization cross sections (ICS) have been published
The results of all these theoretical predictions are usually compared among them with the purpose of deciding whether one model or correction is more adequate to explain the experimental data. This requires using the aforementioned atomic parameters, which must be, in turn, either determined experimentally or calculated by some theoretical model [16]. Those estimates need the consideration of experimental uncertainties, which are not usually taken into account to check the validity of the theories

Summary

Introduction

Particle Induced X-ray Emission (PIXE) is a powerful analytical technique [1], which requires a reliable knowledge of ionization cross sections by charged particle impact and the subsequent process of characteristic X-ray emission, including the atomic parameters involved, such as fluorescence yields, Coster-Kronig transition probabilities, and relative emission rates [2]. Since the first half of the 20th century, hundreds of papers regarding the measurement of X-ray production cross sections (XRPCS) and derived ionization cross sections (ICS) have been published This includes K-, L- and M-Xrays [3,4,5,6,7]. The results of all these theoretical predictions are usually compared among them with the purpose of deciding whether one model or correction is more adequate to explain the experimental data This requires using the aforementioned atomic parameters, which must be, in turn, either determined experimentally or calculated by some theoretical model [16]. Those estimates need the consideration of experimental uncertainties, which are not usually taken into account to check the validity of the theories. A description of how those uncertainties may prevent any definite conclusion about the validity of theoretical models or atomic parameters databases employed in the predictions, for K and L shells

X-ray production cross sections and atomic parameters databases

Conclusions