Measurement and Analysis of Neutrons Emitted from Fission of Transuranium Nuclides

超铀核素裂变中子的测量与分析

• 批准号: 07458103
• 负责人: KIMURA Itsuro
• 金额: $ 4.61万
• 依托单位: Kyoto University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07458103/
• 关键词: Transuranium nuclides; Nuclear fission; Fission fragment; Fission nuetrons; U-235; U-233; Pu-239; Delayd neutrons; ウラン233; アメリシウム242m; 超ウラン核種; レベル密度パラメータ; マルチモード核分裂; プルトニウム239; アバランシェカウンタ

1.Average number of the prompt neutrons per a thermal neutron fission of Pu-239 was obtained as a function of fragment mass number by means of simultaneous measurement of velocities and energies of two fission fragments. The result agreed with the predicated value by using the Brosa's multimode fission model.2.A new simultaneous measurement system of fission fragments and prompt neutrons was designed and completed. Its characteristics were obtained.3.By making use of a supermirror neutron guide tube of Kyoto University Reactor (KUR), a fission chamber with a thin sample layr and the system described above, the mass and the energy of fission fragments and the number and the energy of prompt neutrons for U-235 and U-233 were measured. By using the experimental results, the division of mass and energy in the fission process was investigated. In addition to this, the level density parameters for fission fragment nuclides were obtained by the results.4.A new computer program system for the calculation of prompt fission neutron spectra, and those for Np-237, Cm-242, -243, -244, -246, -248 were obtained by this system.5.The Brosa's multimode fission model was applied to calculate the prompt fission neutron spectra. The obtained spectrum of the fast neutron fission of Np-237 satisfactorily agreed with the measured.6.By using Moriyama's formula and some experimental data, the systematics of delayd neutron yield of actinoide nuclides were investigated and applied to explain the reason of their decrement for higher actinoids.

1.通过同时测量两个裂变碎片的速度和能量，得到了Pu-239一次热中子裂变的平均提示中子数与裂变碎片质量数的函数关系。结果与Brosa多模裂变模型的预测值一致。设计并完成了一套新的裂变破片和瞬发中子同步测量系统。得到了其特性。利用京都大学反应堆（KUR）的超镜中子导管、薄样品层裂变室和上述系统，测量了U-235和U-233裂变碎片的质量和能量以及提示中子的数量和能量。利用实验结果，对裂变过程中的质能划分进行了研究。此外，还得到了裂变碎片核素的能级密度参数。利用该系统获得了一个新的计算裂变中子能谱的计算机程序系统，并计算了Np-237、Cm-242、-243、-244、-246、-248的中子能谱。应用Brosa多模裂变模型计算了瞬发裂变中子能谱。所得的Np-237的快中子裂变谱与测量值吻合得很好。利用Moriyama公式和一些实验数据，研究了锕系核素延迟中子产率的系统分布，并应用于解释高锕系核素延迟中子产率衰减的原因。

项目成果

木村 逸郎: "核分裂の実験的研究の現状" 日本原子力学会誌. 39・9. 733-738 (1997)

木村一郎：“核裂变实验研究的现状”日本原子能学会杂志39・9（1997）。

K.Nishio: "A System for Correlation Measurement of Fission Fragments and Prompt Neutrons for Thermal Neutron Induced Fission" Nuclear Instruments and Methods in Phys.Res.A385. 171-178 (1997)

K.Nishio：“用于热中子诱发裂变的裂变碎片和瞬发中子的相关测量系统”核仪器和方法，Phys.Res.A385。

K.Nishio: "Measurement of Fragment Mass Dependent Kinetic Energy and Neutron Multiplicity for Thermal Induced Fission of Pu-239" Journal of Nuclear Science and Technology. 32. 404-414 (1995)

K.Nishio：“测量 Pu-239 热诱导裂变的碎片质量相关动能和中子多重性”核科学与技术杂志。

K.Nishio, Y.Nakagome, I.Kimura, et al.: "Multiplicity and Energy of Neutrons from ^<235>U (n, f) Fission Fragment" Nuclear Physics.

K.Nishio、Y.Nakagome、I.Kimura 等人：“^<235>U (n, f) 裂变碎片中子的多重性和能量”核物理。

K.Nishio: "Measurement of Level Density Paramenters of Fission Fragments Following Thermal Neutron Induced Fission of U-235" Journal of Nuclear Science and Technology. 34・5. 439-444 (1997)

K.Nishio：“U-235热中子诱发裂变后裂变碎片的能级密度参数的测量”核科学与技术杂志34・5（1997）。