1. Department of Physics, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB3 0HE, Cambridge, UK
2. Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24–25, Potsdam-Golm D-14476, Germany
3. Department of Industrial Engineering (DIIn), Salerno University, Fisciano, SA, Italy
4. Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Protonen für die Therapie, Hahn-Meitner Platz 1, 14109, Berlin, Germany
5. Beuth Hochschule für Technik Berlin, Fachbereich II – Mathematik – Physik – Chemie, Luxemburgerstr. 10, D-13353, Berlin, Germany
6. Department of Chemical Engineering & Biotechnology, University of Cambridge, Philippa Fawcett Drive, CB3 0AS, Cambridge, UK