Y. E. Gunanto
Dept. of Math.Educ., Universitas Pelita Harapan, Karawaci, Tangerang 15811

B. Kurniawan
Department of Physics, University of Indonesia, Kampus UI, Depok

S. Poertadji
Department of Physics, University of Indonesia, Kampus UI, Depok

A. A. Wisnu
Centre of Technology for Nuclear Industrial Materials (PTBIN)-BATAN, Kawasan Puspiptek, Serpong 15341, Tangerang Selatan

A. Purwanto
Surya Institute, Gading Serpong, Tangerang 15811

H. Tanaka
Department of Physics, Tokyo Institute of Technology, Tokyo, Japan 152-8551

T. Ono
Department of Physics, Tokyo Institute of Technology, Tokyo, Japan 152-8551