[en] Abstract:The abundance of radiocarbon in natural samples has been measured using the Tandetron mass spectrometer at Nagoya University. The result shows that the radiocarbon dating is possible with the precision of less than 0.5% error using the graphitized target. The error is mainly due to the statistical uncertainty deduced from total ¹⁴C count and can be reduced if more ¹⁴C count is obtainable. The ages measured for samples of less than several thousand years old are consistent with the values by the beta decay counting method. The sample preparation to provide a proper solid target and the results for testing the performance of the spectrometer are described. (author)

[en] Fast neutron cross sections of Be were studied. We have performed measurements of double-differential (3.25, 3.9, 4.5, 6.4 and 7.0 MeV) and total (1.0 to 14.0 MeV) neutron cross sections, and attempted to analyze the (n,α) reaction to interpret energy distributions of continuum neutrons, and to get informations on mechanism of the (n,2n) reaction. Present results for total, elastic and (n,2n) cross sections show good agreements with the data given by ENDF/B-IV. For inelastic scattering cross sections and secondary neutron energy spectra, present results support the data by Drake, rather than those by ENDF/B-IV. The analysis of the energy distributions of continuum neutrons, and of the (n,α) reaction suggested the contribution of (n,α₁) reaction to (n,2n) cross sections

[en] /sup 7/Li double-differential neutron cross sections were measured with time-of-flight method for En.5.1, 6.6 and 15.4 MeV at six laboratory angles between 27.5¹ and 140⁰. The results are compared with the evaluated data, and the emission spectra are analyzed. This work is important in various branchs of fusion reactor neutronics such as evaluation of tritium production, neutron shielding and radiation heating. 14 refs

[en] A data correction method was developed to correct double-differential neutron emission data for sample-size effects and the sample-dependent background due to contaminant source neutrons. The latter correction proved to be very important to obtain consistent results. The correction is based on the following: (i) Monte Carlo simulation of neutron scattering considering the kinematics and finite experimental geometry, (ii) derivation of the energy-angular neutron emission data that provide simulation results consistent with the experimental data, and (iii) correction for sample-size effects and the sample-dependent background by, in a unified manner, using the correction factor deduced by the simulation. The present method was applied successfully for a wide range of target masses. The correction procedure, examples of the correction and the effect of the input data on the correction are presented. (orig.)