1. Institute of Nuclear Science and Technology; University of Nairobi; PO Box 30197-00100; Nairobi; Kenya
2. Applied Nuclear and Radiation Physics Group; Department of Physics; University of Nairobi; PO Box 30197-00100; Nairobi; Kenya
3. Department of Land Resource Management and Agricultural Technology; University of Nairobi; PO Box 30197-00100; Nairobi; Kenya