1. Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Planta 2, 08930 Sant Adrià del Besòs, Barcelona, Spain
2. Institute of Radiation Physics, Helmholtz-Zentrum Dresden − Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
3. Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain