Based on the neutron induced fission fragment mass distribution data up to neutron energy 20 MeV measured with the double kinetic energy method （KEM） and the radio active method （RAM）, the systematics of fission f...Based on the neutron induced fission fragment mass distribution data up to neutron energy 20 MeV measured with the double kinetic energy method （KEM） and the radio active method （RAM）, the systematics of fission fragment mass distribution was investigated by using 5 Gaussian model and the systematics parameters were obtained by fitting the experimental data. With the systematics, the yields of any mass A and at any energy in the region from 0 to 20 MeV of neutron energy can be calculated. The calculated results could well reproduce the experimental data measured with KEM, but show some systematical deviation from the data measured by RAM, which reflects some systematical deviations between the two kinds of measured data. The error of systematics yield was calculated in an exact error transformation way, including from the error of the experimental yield data to the error of the discrete parameters, then to the systematics parameters, and at last to the yield calculated with systematics.展开更多
Low energy neutron induced fission of 235U is studied in the framework of the multi-modal fission model. The fission fragment properties, such as the yields, the average total kinetic energy distribution and the avera...Low energy neutron induced fission of 235U is studied in the framework of the multi-modal fission model. The fission fragment properties, such as the yields, the average total kinetic energy distribution and the average neutron separation energy, are investigated for incident neutron energies from thermal to 6.0 MeV. The multi-modal fission approach is also used to evaluate the prompt fission neutron multiplicity and spectra for the neutron-induced fission of 235U with an improved version of the Los Alamos model for incident neutrons below the （n, nf） threshold. The three most dominant fission modes are taken into account. The model parameters are determined on the basis of experimental data. The calculated results are in good agreement with the experimental data.展开更多
It is necessary to develop a series of fission chamber in different sensitivities from high to very low sensitivity for covering the yield range of fusion neutron 10^13～10^21n·s-1 produced by ITER. The high sens...It is necessary to develop a series of fission chamber in different sensitivities from high to very low sensitivity for covering the yield range of fusion neutron 10^13～10^21n·s-1 produced by ITER. The high sensitivity fission chamber employs high purity 235U as fissile material, 1 ～ 1.5 g 235U is coated on the multi-electrodes, its structure is shown in Fig. 1 （a）.展开更多
文摘Based on the neutron induced fission fragment mass distribution data up to neutron energy 20 MeV measured with the double kinetic energy method （KEM） and the radio active method （RAM）, the systematics of fission fragment mass distribution was investigated by using 5 Gaussian model and the systematics parameters were obtained by fitting the experimental data. With the systematics, the yields of any mass A and at any energy in the region from 0 to 20 MeV of neutron energy can be calculated. The calculated results could well reproduce the experimental data measured with KEM, but show some systematical deviation from the data measured by RAM, which reflects some systematical deviations between the two kinds of measured data. The error of systematics yield was calculated in an exact error transformation way, including from the error of the experimental yield data to the error of the discrete parameters, then to the systematics parameters, and at last to the yield calculated with systematics.
基金Supported by Research Fund for Doctoral Program of Higher Education of China (200610001023)Major State Basic Research Development Program of China (2007CB209903, 2008CB717803)National Fund for Fostering Talents of Basic Science of China(J0630311)
文摘Low energy neutron induced fission of 235U is studied in the framework of the multi-modal fission model. The fission fragment properties, such as the yields, the average total kinetic energy distribution and the average neutron separation energy, are investigated for incident neutron energies from thermal to 6.0 MeV. The multi-modal fission approach is also used to evaluate the prompt fission neutron multiplicity and spectra for the neutron-induced fission of 235U with an improved version of the Los Alamos model for incident neutrons below the （n, nf） threshold. The three most dominant fission modes are taken into account. The model parameters are determined on the basis of experimental data. The calculated results are in good agreement with the experimental data.
文摘It is necessary to develop a series of fission chamber in different sensitivities from high to very low sensitivity for covering the yield range of fusion neutron 10^13～10^21n·s-1 produced by ITER. The high sensitivity fission chamber employs high purity 235U as fissile material, 1 ～ 1.5 g 235U is coated on the multi-electrodes, its structure is shown in Fig. 1 （a）.
