1. Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research, P.O. Box 4110 Yaoundé, Cameroon
2. Research Centre for Nuclear Science and Technology, Institute of Geological and Mining Research, P.O. Box 4110 Yaoundé, Cameroon, Nuclear Physics Laboratory, Faculty of Science, University of Yaoundé I, P.O. Box 812 Yaoundé, Cameroon