奇特核和超核中的晕现象

讨论奇特核和超核中的各种晕现象. 根据密度相关零程对力的相对论连续谱Hartree Bogoliubov理论给出的计算结果， 预言了中子滴线附近的Ca原子核中可能存在着巨晕， 并简要介绍了O， Ni， Zr， Sn和Pb等一些质子幻数核从质子滴线到中子滴线之间的原子核基态性质. 随后给出超核内的晕现象研究， 如Ca超核内的中子晕和153ΛC内的单Λ超子晕. Halos in the relativistic continuum Hartree Bogoliubov (RCHB) theory are investigated，including giant halo in the even N Ca isotope near neutron drip line，halos in hypernuclei and the hyperon halos in 153ΛC.     

Neutron Halos in the Excited States of Spherical Nuclei Near the β-Stable Line

The newly discovered neutron halos in the excited states of nuclei 12B, 13C, and 209pb are studied by therelativistic mean-field theory. The calculated binding energies are very close to the experimental ones. The experimentally extracted root-mean-square radii of the last neutron with different occupations in nuclei are well reproduced bycalculations. New candidates for the neutron halos in excited states are predicted and are useful for further search ofneutron halos in the excited states of stable nuclei.     

Structure of Light Nuclei on Neutron Drip Line

In order to extend the conventional shell model (SM) calculation with harmonic oscillator bases to light nuclei on neutron drip line, a self-similar-structure shell model (SSM) is proposed. We do this by a rescaling of both the kinetic and potential energy terms of the harmonic oscillator so that the single-particle orbit in SSM has its own state(orbit)-dependent frequency. Meanwhile, a new method to imitate the Woods-Saxon potential with harmonic oscillator potential is introduced. By the rescaling method and imitation procedure, all light exotic nuclei together with the light stable nuclei are studied in a unified way. The results are in good agreement with experimental data. Furthermore, the puzzle of the unexistence of ⁵He, ^{10Li and 13B is naturaUy explained in SSM.}     

Triton-Clustering in Light Nuclei Near the Neutron Drip Line

Triton-clustering in light nuclei near the neutron drip line is analyzed from their binding energies. Various propertie! of these exotic nuclei are explained.     

利用直接核反应研究轻丰中子核的奇特结构

直接核反应(包括弹性散射、非弹性散射、转移反应等)是研究丰中子核奇特结构的常用实验手段之一。以6,8He、11Li、11,12Be、14,15B、15,16C等N=8附近核的结构研究为例,综述了如何利用这几种反应从实验上研究丰中子核的奇特结构。利用6,8He,11Be等晕核在质子和氘靶上的弹性散射数据,拟合得到了这些反应体系的有效相互作用(光学势)。利用16C在质子和氘靶上的非弹性散射数据,抽取了16C 的形变参数,结果表明16C的形变不可忽略。利用单核子转移反应,定量研究了8He, 11,12Be等丰中子核基态及低占据态中的p-,s-,以及d-波成分的强度。结果表明:8He基态中的4个价中子,除了可以构成正常的 (0p_3/2)4 组态外,还有一定的几率构成($ 0 p_{3/2} $)2(0p_1/2)2组态;12Be的基态以d波闯入为主,而其临近的11Be的基态以s波闯入为主。     

轻丰中子核反应中子集团产生截面的理论研究

采用Boltzmann-Langevin方程研究了能量为35MeV/u的¹⁴Be, ⁸He,⁶He,¹¹Li,¹⁷B,¹¹Be,¹⁹C与¹²C靶的反应,计算了产生中子集团的截面, 发现^14,Be与¹²C靶反应产生⁴n的截面与实验值符合得很好. 通过这几个入射核与¹²C靶形成中子集团截面的对比, 发现核的晕中子越多产生中子集团的截面越大, 晕中子数相同时, 质量数越大产生中子集团的截面越大.中子集团可能主要来自晕核子.     

奇异核性质的研究

介绍了用放射性核束研究奇异核性质的物理问题, 分析了理论研究的主要方法、模型和现状, 并就对关联、连续态与束缚态的耦合、壳效应和自旋 轨道相互作用、质子晕等问题作了进一步的讨论．We briefly present the physical aspects in the study of exotic nuclei with radioaction nuclear beams and introuduce the main theoretical methods,models and present status. A few theoretical problems,such as....     

Study of Exotic Nuclei

A high-sensitive fluorescence cell has been developed with an aim to perform laser spectroscopy of exotic nuclei. This fluorescence cell has been tested off-line for stable isotope ¹³³Cs. Also, an investigation of the nuclear root mean square (r.m.s.) charge and neutron radii, and of the binding energies of the cesium long isotopic chain has been carried out in the relativistic mean field (RMF) and relativistic Hartree–Bogoliubov (RHB) formalisms. The RMF/RHB calculations are compared with the experimental data and are found to be in good agreement.     

Search for Signs of Neutron and Proton Halos in the Excited Isobaric Analog States of A = 14 Nuclei

JETP Letters - The experimentally determined atomic ionization potentials IP1 of lanthanides and actinides are analyzed. A semiclassical method is used to determine the dependence of the orbital...     

A Theoretical Analysis of Mid-Mass Neutron Halos

The present contribution summarizes the content and slightly updates the discussion of a recently proposed theoretical analysis of the halo phenomenon in many-fermion systems. We focus here on applications to potential neutron halos in mid-mass nuclei.     

Exotic Isomers in Deformed Atomic Nuclei

Excited states of atomic nuclei can have long half lives, due to the angular-momentum couplings of unpaired nucleons. Such isomeric states provide opportunities for exploring novel nuclear physics, astrophysics and physics at the atomic/nuclear interface. This review focuses on the properties of isomers in deformed nuclei, and emphasises the importance of axial symmetry in preserving the integrity of the K quantum number. A region of neutron-rich nuclei around ¹⁸⁸Hf (Z=72, N=116) is predicted to have exceptional isomer properties, and experimental advances are now opening up this region to detailed investigation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Quantum Barrier Penetration Studies with Oriented Nuclei: Proton and Neutron Emission from Exotic Isotopes

We report a programme of novel experiments involving direct proton emission and β-delayed proton and neutron emission for exotic nuclei oriented at low temperatures. Full modelling of the quantum tunneling and angular distribution has been made for the first time for these processes. Their study has application in many fields of natural science. The study of barrier effects involving angular momentum and non-spherical deformation can be approached more directly via single-particle emission than via alpha decay, which suffers from complications relating to preformation of the alpha particle. Using the new formalism, predictions are presented for angular distributions of β-delayed neutrons from oriented ¹³⁷I and of direct proton emission from oriented ¹⁴⁷Tm. This revised version was published online in September 2006 with corrections to the Cover Date.     

高温核的奇异衰变过程

本文简要评述了中能重离子碰撞中可能存在的奇异密度分布形状──气泡核和环形核的形成,并论述了实验观测方面的可能特征． Possible existence of the exotic density shapes-the formation of nuclear bubbles and rings-in the domain of intermediate energy heavy ion collisions have been briefly reviewed. Some experimental consequences were dicussed.     

Three-Body Forces and Neutron-Rich Exotic Nuclei

Physics of three-body forces in connection to exotic nuclei will be discussed. Three-nucleon forces (3NF), especially Fujita–Miyazawa 3NF, are shown to be the key for the solution to the long-standing problem of oxygen drip line, which deviates from basic trend towards the stability line. Three-body forces produce repulsive modifications to effective interaction between valence neutrons, and make the ground states less bound. The oxygen drip line is then located at the right place. The relation to the neutron matter is presented. Applications to Ca isotopes will be presented. The shell evolution due to the 3NF depicts the raising of single-particle energies and the widening of splitting among the orbits. This is in contrast to the so-called shell quenching. The 2⁺ levels are calculated for Ca isotopes, suggesting about the same sub-magic structure for N = 32 and 34.     

中能轻奇异核反应总截面的激发函数测量

通过对中能区和相对论能区反应总截面的比较, 可对了解核中核子密度分布的尾巴分量提供重要的信息, Ｇｌａｕｂｅｒ 模型的计算总是低估中能区的反应总截面, 对中子晕核和中子皮核, 这种低估更为严重． 因此, 基于 Ｇｌａｕｂｅｒ 模型从反应总截面提取核的大小存在着一些问题． 对一些轻的奇异核进行中能区核反应总截面的激发函数测量可能会有助于上述问题的解决.A comparison of interaction cross section at relativistic and intermediate energy provides important information about the existence of tail component in the density distribution. The Glauber model calculation always underestimates the total reaction cross section at intermediate energy. The differences are enhanced for halo and skin nuclei. The method to extract the size of nuclei via Glauber model seems to have some ambiguity. The excitation function of total reaction...     

Neutron and Alpha Structure in Neutron Deficient Nuclei in Astrophysics

The paper includes discussions on the important role of neutron and alpha configurations in proton-rich nuclei in nuclear astrophysics in terms of nucleosynthesis under extremely high-temperature hydrogenburning conditions. The p-process, which is supposed to take place at the very early epoch of type II supernovae, has considerable neutrons and alphas together with protons. The alpha-induced reactions on proton-rich unstable nuclei in the light mass regions is expected to play a crucial role, but very few of them were investigated well yet because of the experimental difficulties. Specifically, I report our recent experimental effort for the breakout process from the pp-chain region, 7Be(α ,γ )11C(α ,p)14N under the p-process. The neutron-induced reactions on proton-rich nuclei, which is even more a challenging subject, were investigated previously for very few nuclei. One possible experimental method is the Trojan Horse Method (THM). We successfully have applied THM to the 18F(n, )14N reaction study with an unstable beam of 18F.     

Schottky Mass Measurements of Cooled Exotic Nuclei

Projectile fragments of a ²⁰⁹Bi beam were separated in flight with the fragment separator FRS and injected into the experimental storage ring ESR. In the ESR a beam containing up to about 100 different isotopes was cooled to a relative velocity spread of δv/v=10⁻⁶ by means of the electron cooler. The image currents of the ions induced in a Schottky pick-up probe at each turn were recorded. A subsequent Fast Fourier Transformation of these signals yields the revolution frequencies of the different isotopes stored in the ESR. Unknown masses of more than 150 neutron-deficient nuclides in the element range of 52≤Z≤85 have been measured directly by Schottky Mass Spectrometry and in addition more than 60 new masses have been obtained from α-decay chains. These new mass data allow the location of the one-proton dripline and the prediction of the two-proton dripline for heavy nuclides. The experimental masses are compared with different theoretical predictions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Isochronous Mass Measurements of Hot Exotic Nuclei

A novel method for mass measurements of short-lived exotic nuclides is presented. Exotic nuclides were produced and separated in flight at relativistic energies with the fragment separator (FRS) and were injected into the experimental storage ring (ESR). Operating the ESR in the isochronous mode we performed mass measurements of neutron deficient fragments of ⁸⁴Kr with half-lives larger than 50 ms. However, this experimental technique is applicable in a half-life range down to a few μs. A mass resolving power of 110000 (FWHM) has been achieved. Results are presented for the masses of ⁶⁸As, ^70,71Se and ⁷³Br. This revised version was published online in July 2006 with corrections to the Cover Date.