Impact of Tensor Interaction on Beta-Delayed Neutron Emission from Neutron-Rich Nickel Isotopes

The Skyrme energy density functional including tensor interaction is used to describe microscopically multineutron delayed-neutron emission accompanying beta decay of even–even neutron-rich nickel isotopes of mass number in the range of A = 74?80. The respective calculations are performed in the quasiparticle random-phase approximation with allowance for the two-phonon components of the wave function for states of the daughter nucleus. The properties of the lowest quadrupole excitation of ^74,76,78,80Ni are also studied. It is shown that a decrease in the strength of neutron–proton tensor interaction leads to a substantial hindrance of beta decay and to an increase in the probability for delayedneutron emission.     

13C的一个可能的类晕的中子2p态

假设13C是单粒子的2p态的结构,用Glauber多重散射理论研究了入射能量为1GeV的质子在13C上的弹性散射,得到了与实验符合得很好的理论结果.这说明13C可能存在着一个类晕的中子皮.     

A Possible Halo-Like Neutron 2p States of 13C

Assuming a single-particle 2p structure of ¹³C, we study proton-¹³C elastic scattering at the incident energy of 1 GeV in the Glauber multiple scattering theory. A good agreement between theoretical prediction and corresponding experimental data is obtained. The result evidently indicates a possible halo-like neutron skin of ¹³C.     

重离子辐射哺乳动物细胞敏感性的分子机理

研究了用传能线密度125.5keV/μm的12C6+辐照小鼠黑色素瘤、中国仓鼠肺、人的宫颈癌、人的肝癌细胞的敏感性以及DNA双链断裂和DNA双链断裂片段分布,结果表明细胞敏感性与DNA双链断裂之间没有一致的关系,提出了细胞辐射敏感性的一种可能的分子机理,即DNA序列敏感性位点协同DNA双链断裂互补性机理.由此解释了4种细胞系的不同敏感性问题. Four types of cells, melanoma B16, cervical squamous carcinima HeLa, Chinese hamster V79 and hepatoma SMMC 7721, were irradiated by 125.5 keV/μm carbon ions. Celullar sensitivities to irradiation indicated by D50 , DNA double strand break (DSB) and distribution of DSB fragments expressed by molecular weight are studied. The results show that there is not a consistent relationship between cellular sensitivity and DNA DSB induction, a possible molecular mechanism of radiosensitivity which...     

Reaction Rate of Radiative Capture of a Neutron by a 2H Nucleus

Russian Physics Journal - Within the framework of the modified potential cluster model with forbidden states, n2H radiative capture is considered at energies from 10 meV (0.01 eV) to 10 MeV. It is...     

重核裂变过程中阻尼对中子发射的效应

用{c,h,α}核表面方程描写重核的形变, 建立了含中子发射的裂变动力学的耦合Langevin方程, 完成了断点前中子蒸发多重性的蒙特卡罗计算. 比较了不同黏滞系数对结果的影响, 尤其是区分了裂变核系统首次通过鞍点和最后通过鞍点期间的中子发射分布.     

对重丰中子核区合成新核素的思考

分析了Ａ＞１７０质量区丰中子核素的产生、分离和鉴别过程,总结了在这一质量区用较轻中能重离子炮弹打重靶产生新核素的优点．提出了在在线同位素分离器上使用带有优良元素选择性的激光离子源和多层靶加气体传输系统的改进措施． The production, and process of separation and identification of new neutron rich nuclei with mass number A>170 were analyzed. The advantages of producing new isotopes in this mass region by lighter heavy particles on heavy targets were summarized. It is put forward an improvement method that a laser ion source and multilayer target combining with gas jet transport method can be used on on line isotope separator.     

On Possible Sources of Heavy Neutral Particles in Cosmic Rays

We explore some possible mechanisms by which the heavy neutral cosmic particles are accelerated to gain sufficiently high kinetic energies and cause observable effects at detectors on the earth. Our results indicate that all the known sources which are based on the established theories and observations fail to give rise to very high energy with sizable flux intensity. If the heavy neutral particles of kinetic energies of GeV order indeed exist in cosmic rays, there must be certain mechanisms beyond our present knowledge of dark matter and universe evolution.     

Study of Strangeness Photoproduction on the Neutron in the Threshold Region

Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K ⁰ with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K ⁰ + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K ₁, as ~ ?1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K ⁺ Λ.     

中子晕核的松散结构在重离子碰撞动量耗散中的作用

利用同位旋相关量子分子动力学模型, 对比和研究了中子晕核¹⁹B和相等质量稳定核¹⁹F在相同入射道条件下引起核反应动量耗散中的特征.由于中子晕核的松散中子晕结构和小的分离能,与相等质量稳定核相比,在低能区具有减弱动量耗散的特征.但随入射能量的升高,这种晕核结构对动量耗散的 作用减弱.而且对所有质量靶核,所有碰撞参数和中子晕核结构都具有减弱动量耗散的作用.     

Neutron Resonances in Systems of Few Nuclei and Their Possible Role in Radiation of Overdense Stars

Exact analytical solutions of three- and four-body systems made of one light particle and other heavy particles have been obtained in the model of Born?COppenheimer approximation with two-body separable interactions. In the case of neutron scattering on a subsystem of few fixed nuclei the appearance of new resonance quantum states has been shown as well as their dependence on distances between heavy nuclei. The applications of new phenomena to overdense stars radiation are considered.     

Some Possible Asymmetry Effects of Nuclear Matter in Relativistic Heavy Ion Collisions

The asymmetry dependence of nuclear incompraeaibility and that of nuclear critical temperature are calculated baaed on a Thomas-Fermi model with Seyler-Blanchard interaction. It is found that the asymmetry effects are big enough to allow for checking the existence of these effects in relativistic heavy-ion collision experiments.     

重离子反应中质子与中子转移对超重元素合成的影响

研究了采用类弹碎片质量数为变量的一维(1D)主方程(ME)描述重离子熔合反应时的受限制条件, 建立了以类弹碎片中子和质子数为独立变量的二维(2D) ME, 并采用分步差分格式法数值解(2D) ME得到了熔合几率。 新的方法适用于研究任何弹靶组合系统, 给出了与实验符合更好的结果, 为寻求合成超重核的反应道提供了更为宽阔的选择空间。 同时也研究了弹靶的不同同位旋组合对复合核形成截面的影响。 The limitation of the one dimensional master equation with the mass number of project like fragment as the variable is discussed. A two dimensional master equation with neutron and proton numbers of the project like fragment as variables is set up, and solved numerically by means of a two step difference scheme to obtain fusion probability. The new equation is suitable for studying fusion reactions with any projectile target combination, and can better fit the experimental data, so that it can provide a large probability to choose the reaction system for synthesizing a certain superheavy nucleus. The influence of projectile target combinations with different isospins on the cross sections of compound nuclei is studied.     

中、重质量区新核素的合成

论述了远离稳定线核素合成的科学意义,总结了有关新核素合成研究的国内外概况以及中、重质量区远离稳定线核素的主要产生机制．给出了我国合成的一些新核素的半衰期,并与理论预言值进行了比较．简略地叙述了核反应产物的传输、分离以及新核素的鉴别方法.The importance of synthesis of new nuclei far from stability is concisely recounted. The prograsses on synthesis of the new nuclides and the main methods used for producing new nuclei far from stability in the intermediate and heavy mass region is summarized. The half lives of some new nuclides synthesized in china are compared with those calculated based on the gross theory and the microscopic theory. Some examples for transport and chemical separation of the nuclear reaction products...     

CSR能区重离子反应中的介子产生

重离子反应中介子产生的观测对于认识重离子反应动力学和核物质性质具有重要的意义 .讨论了重离子反应中阈能附近介子产生的一些特点和研究现状 ,特别讨论了π介子产生和K+ 介子产生 .在我国兰州重离子冷却储存环上开展这方面的实验研究具有可能性 ,可望得到很有意义的结果 .及时开展这方面实验研究和相应的理论研究是必要的.It is important to measure meson productions in heavy ion collisions in order to understand the dynamics of heavy ion reactions and the properties of nuclear matter. In this paper we review the characteristic and present status of meson productions near the threshold energies in heavy ion collisions. Especially the pion and K + productions are discussed. We point out that it is meaningful and possible to carry out the experimental studies at the CSR. It is necessary to carry out timely the...     

中能重离子碰撞中的中子(质子)发射的同位旋效应

利用同位旋相关的量子分子动力学,对中能重离子碰撞过程中的中子和质子发射的同位旋效应进行了分析.计算结果表明在有动量相关作用条件下,在很宽的能量和碰撞参数范围内,缺中子碰撞系统的中子(质子)发射数强烈地依赖于同位旋相关的核子–核子碰撞截面,而较弱地依赖于对称势.在对丰中子碰撞系统的研究中,上述规律减弱.这样就可以通过实验上对缺中子碰撞系统的中子(质子)发射数的探测,来提取介质中同位旋相关核子–核子碰撞截面的知识.     

低SIS能区重离子碰撞过程的系统性研究

在极端相对论量子分子动力学(UrQMD)模型中加入势能密度泛函形式的势修正、核子-核子弹性散射截面的更细致的介质修正以及碎片重构模式中的同位旋效应后,重点研究低SIS能区(约40～400 MeV/u)重离子碰撞的动力学过程。在较系统地研究此能区重离子碰撞后的轻碎片产生及集体流后,重点研究对高密区对称能密度依赖敏感的观测量。发现:(1)质量对称的Sn系列同位素反应系统,其中子平衡能的系统N/Z分布能敏感探测对称能密度依赖;(2)横速度/动量分布的中子和质子及氢同位素的椭圆流比vn2/vp,H2敏感依赖于对称能。经采用多组核物质标量不可压缩系数K0值差别很小、对称能斜率参数L值相差较大的Skyrme势参数计算并对FOPI/LAND相应数据做χ2分析后抽取的L值为(89±45)MeV。