1. Physics Department, University of Trieste, via A. Valerio 2, Trieste 34127, Italy
2. CNR-IOM, Laboratorio TASC, S.S. 14 Km 163.5, Basovizza, Trieste, 34149, Italy
3. Vinča Institute of Nuclear Sciences – National Institute of the Republic of Serbia, University of Belgrade, P. O. Box 522, RS-11001 Belgrade, Serbia