Measurement of double differential alpha particle emission cross sections of beryllium for 14.1 MeV incident neutron

Alpha particle spectra from 9Be(n,2n)2α reaction were measured with 14.1 MeV neutrons for 30-105 deg angle points. Employing the E-TOF two dimensional data acquisition system, measurement with good S-N ratio was undertaken. In order to deduce DDX data from raw spectrum, Monte-Carlo simulations which took locations of sample and energy loss into consideration were done. Using the result of calculation, corrections for raw data were made. The results of experiments were compared with evaluated nuclear data ENDF/B-VI, and some discrepancies were found. On the other hand, we performed statistical calculations based upon reaction kinematics which assumed 3-body sequential decay. The calculated DDXs were compared with experimental data for alpha particles and neutrons to study consistency. From this analysis, it was suggested that the 3-body sequential decay could describe the continuum of the alpha-particle spectra, without assumption for unknown reaction channels as in the case of ENDF/B-VI. (author)