MEASUREMENT OF NEUTRON-INDUCED NEUTRON-PRODUCING CROSS SECTIONS OF 6Li AND 7Li AT 18.0 MeV
Department of Physics, Japan Atomic Energy Research Institute
Tokai-mura, Ibaraki-ken 319-11, Japan
Mamoru BABA, Naohiro YABUTA, Tsukasa KIKUCHI, Masumi ISHIKAWA, Naohiro HIRAKAWA and Kazusuke SUGIYAMA
Faculty of Nuclear Engineering, Tohoku University
Sendai-shi, Miyagi-ken 980, Japan
The energy and angular double-differential neutron emission cross sections (DDX), d2σ/dE'dΩ, of 6Li and 7Li have been measured at 12 angles from 30 to 150° with incident neutrons of 18.0 MeV. The measurement was based on the time-of-flight (TOF) method. Measured DDXs have been compared with predictions from evaluated nuclear data and some problems with the evaluations were found. It was also found that the angular distributions of the continuum energy neutrons have a clear systematic trend that is dependent on their Q-values. Neutrons corresponding to low excitation energy in residual nucleus showed strong forward angular distributions. A spherical optical model calculation was performed for the elastically scattered neutrons of 6Li. The continuum neutron spectra of 6Li were analyzed in terms of the Final-State Interaction theory. The analysis could reproduce the experimental spectra very well with a large contribution from the 3S1 partial wave in the d-α system.
KEYWORDS: Measured DDX, 6Li, 7Li, 18.0 MeV, time-of-flight, evaluated nuclear data, optical model calculation, angular distribution, Final-State Interaction