Energy loss of light ions (H+ and He+) in matter: high accuracy measurements and comparison with the FEG model

Abstract

The phenomenon of energy loss that occurs when an ion interacts with matter, also called stopping power, has been investigated for more than a century, and has provided findings of interest. However, reliable procedures for obtaining accurate experimental measurements and a fully theoretical comprehension of the process are tasks still in high demand by the scientific community. Moreover, stopping power data are prerequisites in several applications in modern science, such as engineering, ion implantation and modification of materials, damage to electronics devices (e.g. space radiation), medical physics (e.g. proton therapy), among others. In this thesis we i) develop a rigorous experimental protocol to measure stopping power with high precision, and ii) investigate 1 the collapse of the free electron gas (FEG) model in energy loss of light ions (protons) at a low energy range in transition and rare-earth metals. In the first part, we present an approach to obtain, with high accuracy, the stopping cross sections in the pure materials Al and Mo for protons in the energy range of [0.9 − 3.6] MeV by means of the transmission method. The traceability of the sources of uncertainties are fully evaluated and the final accuracy of the results is 0.63 % (0.32 % rand. and 0.54 % syst.) for Al, and 1.5 % (0.44 % rand. and 1.4 % syst.) for Mo, with both results primarily limited by the quality and homogeneity of the stopping foils. For Al, this high accuracy represents an improvement com-Foremost I want to express my gratitude to my advisor, co-author and friend Prof. Dr. Manfredo H. Tabacniks. His guidance, encouragement over the years, vast scientific knowledge and notable vision in many other areas (e.g. ethics and interaction with participants) have always inspired me to reach interesting findings in physics and in life, always expanding my mind. Without his support, the accomplishments here presented would never have been possible. Thank you so much.