分类: 物理学 >> 核物理学 提交时间: 2024-01-21
摘要: To fulfill the needs of neutron capture reaction cross-section measurement in keV energy scale in the field of nuclear astrophysics and advanced nuclear energy system development, the 4 BaF2 Gamma-ray Total Absorption Facility (GTAF) developed by the Key Laboratory of Nuclear Data of the China Institute of Atomic Energy (CIAE) has been transplanted and installed at the Back-streaming White Neutron Source (Back-n) of the China Spallation Neutron Source (CSNS) in 2019. A series of results has been achieved and published based on the GTAF since then, and due to which the needs of reducing backgrounds are becoming increasingly urgent. In order to understand the origins of backgrounds and to optimize the facilities, a detailed simulation program using GEANT4 toolkits was established and presented in this paper. To demonstrate the availability of the proved codes, several practical examples of assisting the process of experimental data and helping verify the optimization proposition are also shown in this paper.
分类: 物理学 >> 核物理学 提交时间: 2024-01-05
摘要: A benchmark experiment on 238U slab samples was conducted using a deuteriumtritium neutron source at the China Institute of Atomic Energy. The leakage neutron spectra within energy levels of 0.816 MeV at 60 and 120 were measured using the time-of-flight method. The samples were prepared as rectangular slabs with a 30 cm square base and thicknesses of 3, 6, and 9 cm. The leakage neutron spectra were also calculated using the MCNP-4C program based on the latest evaluated files of 238U evaluated neutron data from CENDL-3.2, ENDF/B-VIII.0, JENDL-5.0, and JEFF-3.3. Based on the comparison, the deficiencies and improvements in 238U evaluated nuclear data were analyzed. The results showed the following. (1) The calculated results for CENDL-3.2 significantly overestimated the measurements in the energy interval of elastic scattering at 60 and 120. (2) The calculated results of CENDL-3.2 overestimated the measurements in the energy interval of inelastic scattering at 120. (3) The calculated results for CENDL-3.2 significantly overestimated the measurements in the 38.5MeV energy interval at 60 and 120. (4) The calculated results with JENDL-5.0 were generally consistent with the measurement results.
分类: 核科学技术 >> 核科学与技术 提交时间: 2023-10-09
摘要: Iron is commonly used as a structural and shielding material in nuclear devices. The accuracy of its nuclear data is critical for the design of nuclear devices. The evaluation data of 56Fe isotopes in the latest version of the CENDL-3.2 library from China was significantly updated. This new data must be tested before it can be used. To test the reliability of this data and assess the shielding effect, a shielding benchmark experiment was conducted with natural Fe spherical samples using a pulsed deuterium- tritium neutron source at the China Institute of Atomic Energy (CIAE). The leakage neutron spectra from the natural spherical iron samples with different thicknesses (4.5, 7.5, and 12 cm) were measured between 0.8-16 MeV after interacting with 14 MeV neutrons using the time-of-flight method. The simulation results were obtained by Monte Carlo simulations by employing the Fe data from the CENDL-3.2, ENDF/B-VIII.0, and JEDNL-5.0 libraries. The measured and simulated leakage neutron spectra and penetration rates were compared, demonstrating that the CENDL-3.2 library performs sufficiently overall. The simulation results of the other two libraries were underestimated for scattering at the continuum energy level.