50,52,53,54Cr光核反应数据评价

通过分析光子诱发52,50Cr核反应的各类实验数据，澄清52Cr光子吸收截面评价数据与中子、质子出射截面测量值间的分歧，给出了52Cr中子出射截面实验数据的修正；选取EGLO模型光子强度函数，结合准氘模型，给出光子吸收截面。在此基础上，采用最新研制的光子与中重核反应计算程序MEND-G，通过优化理论模型参数，包括剩余核的能级密度和对能修正参数，给出光子能量在200 MeV范围内的n、p、${{\rm{\alpha }}}$等粒子出射核反应的截面，52,50Cr的计算结果在30 MeV以下能区很好地符合了现有实验数据，并按国际标准ENDF/B-6库格式给出了50,52,53,54Cr的全套数据文档，便于核工程用户使用。     

钍基熔盐堆用238群中子-48群光子耦合多群常数库的屏蔽基准验证

采用OKTAVIAN脉冲球实验对钍基熔盐堆用AMPX主库格式238群中子-48群光子耦合多群常数库进行了屏蔽基准验证,重点检验了该库中的F,Li,Be,C、Al,Si,Cr,Ni,Zr,Co,Cu,Mn,Mo,Nb,Ti,W,Pb同位素/元素的数据。采用SCALE 5.1程序系统中的XSDRN-PM程序进行一维屏蔽问题计算,将计算结果与实验测量数据及MCNP程序计算结果进行比较,发现中子泄漏谱的符合程度较好,而光子泄漏谱检验中发现大多数核素都出现了不同程度的高估。通过对GENDF格式到AMPX格式的转换程序MILER-4进行修正,解决了这一问题。通过对多群常数库的屏蔽基准验证,进一步证明了该库的可靠性。OKTAVIAN pulsed sphere experiment was used for Shielding Benchmarks of the AMPX formatted multi-group (238n-48γ) coupled neutron-gamma cross-section library for Thorium Molten Salt Reactor, of which the following isotopes/elements were checked-F, Li, Be, C, Al, Si, Cr, Ni, Zr, Co, Cu, Mn, Mo, Nb, Ti, W. One dimension shielding problem was calculated using XSDRN-PM program of SCALE 5.1 code system and results were compared with experiment results and MCNP calculated results, which shows that neutron leakage spectra agree well. Calculated results of photon leakage spectra of most facilities compared with MCNP results and experiment data are over-rated. MILER-4 code which is used for converting GENDF files produced by NJOY to the AMPX master library format is revised to solve this problem. The shielding benchmark verifications confirm the reliability of this new library.     

核数据共享研究

科学数据共享的重要性已经引起了我国政府的重视,介绍了中国核数据中心在核数据共享项目进行的研究工作.该研究工作主要包括建立核数据数据库和共享平台的建设两方面的内容.The importance of scientific data sharing has been attracted attention of our government. The research of nuclear data sharing in China Nuclear Data Center are introduced. The work includes research of nucler database and development of online service system.     

核数据研究及应用的进展与展望

核数据包括核反应数据与核结构及放射性衰变数据。核反应数据是描述入射粒子与原子核发生相互作用的数据，核结构数据是反映核素自身基本性质方面的数据。核数据是核能利用、核工程建设、核技术应用以及核物理基础研究等方面不可缺少的基础数据，在核医学、材料分析、资源勘探、环境监测、宇航技术以及核天体物理研究领域也有着广泛的应用。本文简要介绍了核数据的种类、产生及应用，评述了国际核数据研究与应用现状以及发展动态、我国核数据研究现状及存在的问题，并对我国核数据工作未来发展方向提出了几点建议。     

Energy spreading,equipartition, and chaos in lattices with non-central forces

We numerically study a one-dimensional,nonlinear lattice model which in the linear limit is relevant to the study of bending(flexural)waves.In contrast with the classic one-dimensional mass-spring system,the linear dispersion relation of the considered model has different characteristics in the low frequency limit.By introducing disorder in the masses of the lattice particles,we investigate how different nonlinearities in the potential(cubic,quadratic,and their combination)lead to energy delocalization,equipartition,and chaotic dynamics.We excite the lattice using single site initial momentum excitations corresponding to a strongly localized linear mode and increase the initial energy of excitation.Beyond a certain energy threshold,when the cubic nonlinearity is present,the system is found to reach energy equipartition and total delocalization.On the other hand,when only the quartic nonlinearity is activated,the system remains localized and away from equipartition at least for the energies and evolution times considered here.However,for large enough energies for all types of nonlinearities we observe chaos.This chaotic behavior is combined with energy delocalization when cubic nonlinearities are present,while the appearance of only quadratic nonlinearity leads to energy localization.Our results reveal a rich dynamical behavior and show differences with the relevant Fermi–Pasta–Ulam–Tsingou model.Our findings pave the way for the study of models relevant to bending(flexural)waves in the presence of nonlinearity and disorder,anticipating different energy transport behaviors.     

Neutron activation cross section data library

To satisfy the requirements of nuclear reaction cross sections in nuclear engineering applications and nuclear physics studies, the Neutron Activation Cross Section Data Library has been established. 818 target nuclei including unstable target or isomeric target nuclei are considered in this library. The induced neutron energy range region is between 10^-5 eV and 20 MeV. The standard ENDF-6 format is adopted, including general information, reaction cross sections, multiplicities, and so on. The recommended reaction cross sections were obtained using UNF code system and FDRR nuclear model codes or systematic analysis based on available experimental data. The full evaluated dataset containing the evaluated activation cross sections is openly available at http://doi.org/10.57760/sciencedb.j00113.00024.     

LaFeO3纳米材料电四极超精细相互作用TDPAC测量

用时间微分扰动角关联方法测量了LaFeO3纳米中的电四极超精细相互作用. 扰动角关联探针核14057La 14058Ce由139La(n,γ)140La反应产生, 实验只观察到一个La晶位的四极相互作用. 在室温下， 20和40 nm 以及晶体LaFeO3的四极相互作用频率ω0分别为 687.4 , 698.3 和742.9 Mrad/s , 频率分布宽度系数σ分别为 0.014, 0.009和0.001, 电场梯度不对称系数η=0. 实验数据表明, 电场梯度主轴与晶轴方向一致; 样品具有菱方结构, 晶体到纳米发生菱方向正交结构转变, 纳米尺度越小, 越趋于正交结构; 由于邻近核的扰动, 随纳米颗粒增大, 四极相互作用频率分布宽度系数σ变小, 晶体时最小. The quadrupole interactions in the nano and crystalline LaFeO3 perovskites have been investigated by TDPAC. The TDPAC probing nuclei 14057La 14058Ce were produced through the nuclear reaction 139La(n.γ)140La at the CIAE heavy water experimental reactor. One electric quadrupole interaction was detected for each material, which is assigned to the La site. The quadrupole interaction frequencies of 687.4, 698.3 and 742.9 Mrad/s with a distribution coefficient of 0.014, 0.009 and 0.001 were observed at room temperature for the 20 and 40 nm nano LaFeO3 and crystalline LaFeO3, respectively. The fitting yielded the EFG asymmetry parameter η=0, which indicates that the principal axes of the EFG is aligned with the crystallographic axes. The experimental results show that the structure of crystalline LaFeO3 is rhombohedral, the changing of the structure towards the orthorhombic structure takes place from the crystalline LaFeO3 to the nano LaFeO3, and the smaller the nano grain size, the larger the change. The frequency distribution is caused by the perturbation of the neighboring atoms, and thus, the distribution coefficient increases with decreasing the nano grain size and the crystalline LaFeO3 arrives at its maximum.     

核反应实验数据库(EXFOR)

核反应实验数据库(EXFOR)及其检索系统提供了丰富的中低能核反应物理信息和数据，已经成为国际上最全面的核反应实验数据汇编。目前，由国际原子能机构核数据科(IAEA/NDS)协调管理，国际核反应数据中心协作网(NRDC)13个成员进行全球性合作，旨在协调国际范围内核反应实验数据的收集、编纂和传播。中国核数据中心(CNDC)作为NRDC成员之一，多年来开展了大量的中子和带电粒子引起的核反应实验测量和建库技术研究。本文介绍了EXFOR数据库的形成、发展和现况，以及数据格式、数据编纂和检索系统，并简要总结了我国核反应实验数据建库及技术研究等方面的工作，如国内期刊检索、EXFOR数据库文档建设、程序开发、国内数据服务及国际合作等。     

20MeV以下快中子与56Fe非弹性散射截面的分歧研究

56Fe的非弹性散射截面在核装置中子输运计算中扮演着重要的角色,但无论从实验数据还是从评价数据,非弹性散射截面都存在很大分歧,它的数据直接影响到核装置的设计、建造与运行维护。本工作从实验数据本身出发,深入分析了不同实验室测得的847 keV的γ产生截面的分歧,经转化后补充非弹性散射截面的实验空白能区,并同时利用满足全截面、去弹截面等截面自洽关系的评价方法推荐了高精度的快中子与56Fe的非弹反应截面结果。积分检验表明,新的非弹截面的改进使得评价数据与积分实验结果一致,较CENDL-3.1的评价数据结果有显著改善。Knowledge about the inelastic scattering cross section of 56Fe is very important in neutron transportation calculation. However there are great discrepancies not only between experimental data but also between evaluated data. More detail analysis was performed for inelastic scattering cross section in the fast range up to 20 MeV where there are significant differences among the main evaluated libraries, mainly caused by the different inelastic scattering cross section measurements. The large discrepancies on 56Fe(n, n₁'γ) cross section which could fill the neutron energy blank of the 56Fe(n,inl) were clarified and were converted to the inelastic scattering cross section of 56Fe. And the high-quality results were evaluated by using the unitarity constrain among total cross section, noelastic reaction and other reactions. The integral experiment result indicates that the new evaluated result of inelastic cross section brings greater improvement than that of CENDL-3.1.