1. Physics and Chemistry Institute, Federal University of Itajubá (UNIFEI), Itajubá, Brazil
2. High Voltage Laboratory Prof. Manuel Luís Barreira Martinez (LAT-EFEI), Federal University of Itajubá (UNIFEI), Itajubá, Brazil
3. Nuclear and Energy Research Institute-IPEN, Cidade Universitária Armando de Salles Oliveira, Butantã, São Paulo 05508-000, Brazil