Fission experiments with secondary beams

Nuclear fission from excitation energies around 11 MeV was studied at GSI, Darmstadt for 76 neutron-deficient actinides and pre-actinides by use of relativistic secondary beams. The characteristics of multimodal fission of nuclei around ²²⁶Th are systematically investigated and related to the influence of shell effects on the potential-energy and on the level density between saddle point and scission. A systematic view on the large number of elemental yields measured gave rise to a new interpretation of the enhanced production of even elements in nuclear fission and allowed for a new understanding of pair breaking in fission.     

Elastic scattering and reactions of light exotic beams

The present work provides a literature survey of elastic scattering of exotic nuclei from ⁶He to ¹⁷F. It presents a set of definitions that allow different analyses to be put into a common language. A calculational approach is proposed that yields consistent results across different beams and targets so that conclusions concerning the influence of virtual and real breakup as well as transfer couplings on the elastic scattering may be drawn. Calculations of elastic scattering around the Coulomb barrier are emphasised, employing a Pb target whose large Z allows the interplay between nuclear and Coulomb forces to be exploited to maximise possible effects arising from proton or neutron haloes or skins. A series of test calculations is performed and where possible compared to data, demonstrating that there are instances where coupling to transfer channels can have a large effect on the elastic scattering angular distributions. By careful choice of target/beam combination, different aspects of the coupling effects may be emphasised.     

Nuclear structure studies on halo nuclei by direct reactions with radioactive beams

The investigation of direct reactions with exotic beams in inverse kinematics gives access to a wide field of nuclear structure studies in the region far off stability. The basic concept and the methods involved are briefly discussed. The present contribution will focus on the investigation of light neutron-rich halo nuclei. Such nuclei reveal a new type of nuclear structure, namely an extended neutron distribution surrounding a nuclear core. An overview on this phenomenon, and on the various methods which gave first evidence and qualitative confirmation of our present picture of halo nuclei, is given. To obtain more quantitative information on the radial shape of halo nuclei, elastic proton scattering on neutron-rich light nuclei at intermediate energies was recently investigated for the first time. This method is demonstrated to be an effective means for studying the nuclear matter distributions of such nuclei. The results on the nuclear matter radii of ⁶He and ⁸He, the deduced nuclear matter density distributions, and the significance of the data on the halo structure is discussed. The present data allow also a sensitive test of theoretical model calculations on the structure of neutron-rich helium isotopes. A few examples are presented. The investigation of few-nucleon transfer reactions in inverse kinematics may provide new and complementary information on nuclear structure, as well as astrophysical questions. The physics motivation and the experimental concept for such experiments, to be performed due to momentum matching reasons at low incident energies around 5–20 MeV/u at the new generation low energy radioactive beam facilities SPIRAL, PIAFE, etc., is briefly discussed.     

神奇有趣的五夸克态

对今年国际上有关五夸克态的实验与理论研究现状作一个总体的评述 ,指出了有待解决的主要问题和相关的一些背景知识 ,并简单介绍了作者所在研究小组的有关研究工作 .     

Recent radioactive ion beam program at RIKEN and related topics

Recent experimental programs at RIKEN concerning RI beams are reviewed. RIKEN has the ring cyclotron (RRC) with high intense heavy-ion beams and large acceptance fragment separator, RIPS. The complex can provide high intense RI-beams. By using the high intense RI-beams, a variety of experiments have been done. Recently, nuclear structure for unstable nuclei has been paid much attention. In special, disappearance and appearance of magic numbers are discussed experimentally and theoretically. Thus, in this review, related experiments concerning disappearance and appearance of magic numbers are described. Finally, future project in RIKEN, RI-beam factory. is introduced briefly.     

Nucleon transfer reactions with exotic beams at ATLAS

We present some recent results from studies of light nuclei using exotic beams from ATLAS at Argonne National Laboratory. Light nuclei far from stability provide ideal testing grounds for modern theoretical methods, and may provide information about astrophysical environments. We focus on the nuclei ⁹Li and ⁷He, populated with the (d,p) and (d,³He) reactions.     

Beam propagation factor of partially coherent beams in gain or absorbing media

The definition of second-order intensity moments in the spatial domain and spatial frequency domain has been generalized for the case that the linear gain or absorbing media are included, where the wave number is generally complex. The formula for beam propagation M²-factor of partially coherent beams in linear gain or absorbing media has been given. The partially coherent flat-topped Schell-model beam is taken as an example. The closed-form expression for the beam propagation M²-factor of partially coherent flat-topped beam in gain or absorbing media has been derived. The changes of the M²-factor in media have been discussed with numerical examples. It can be shown that the M²-factor of flat-topped Schell-model beams in gain or absorbing media depends on the coherent parameter β, the coherent length σ₀, the beam order M, the propagation distance B, the imaginary part of the wave number K_i, as well as the real part of the wave number K_r.     

Fragmentation of relativistic gold nuclei in nuclear emulsion

Basic data are presented on the parameters of fragmentation, multiplicities and angular spectra of low energetic targed associated particles in the interction of ¹⁹⁷Au nuclei of 10.7A GeV.     

Probing the nuclear symmetry energy with heavy-ion reactions induced by neutron-rich nuclei

Heavy-ion reactions induced by neutron-rich nuclei provide a unique means to investigate the equation of state of isospin-asymmetric nuclear matter, especially the density dependence of the nuclear symmetry energy. In particular, recent analyses of the isospin diffusion data in heavy-ion reactions have already put a stringent constraint on the nuclear symmetry energy around the nuclear matter saturation density. We review this exciting result and discuss its implications on nuclear effective interactions and the neutron skin thickness of heavy nuclei. In addition, we also review the theoretical progress on probing the high density behaviors of the nuclear symmetry energy in heavy-ion reactions induced by high energy radioactive beams.      

Recent progress in subatomic particle detection technology

Particle detection technologies have been largely advanced in ,boratory over the past decade. A neutron sphere was built to detect the decay neutron emitted from the implanted unstable nu eleus, whereas a multi-neutron correlation spectrometer was implemented to detect the forward moving neutrons resulting from breakup reactions. Charged particle telescopes are now equipped with double sided Silicon strip detectors which have excellent energy and position resolutions. Large size gas chambers, such as resistive plate chambers, have been developed in order to achieve high Derformances related to timing or position measurements. The advances of these technologies con tribute substantially to such large science project, as LHC-CMS, and to the experiments with the radioactive nucleus beams.     

The experimental study of exotic nuclear states using multi-detector arrays

This contribution outlines the work of the CHARISSA collaboration in the investigation of exotic states in nuclei. It outlines the background to the work, the techniques involved and discusses in detail an experiment to study the cluster structure of ¹²Be.     

Nuclear physics with simple and multi-element detectors and with stable and radioactive beams

The phenomenon of fusion barrier distributions is discussed in the context of a problem already investigated in some detail with simple detection systems, but possessing avenues to studies with multi-detector arrays. The complementarity of research with simple and complex detectors, as well as with stable and radioactive beams, will be highlighted.     

Nuclear Moment Studies with Polarized Radioactive Nuclear Beams

Magnetic dipole and electric quadrupole moments of nuclei in the light-mass neutron-rich region have been studied by taking advantage of spin-polarized radioactive nuclear beams that have been obtained from the projectile fragmentation reaction. Analyses of the results reveal a few interesting phenomena characteristic of nuclear structures in this region. In particular, we report in some detail the latest result on the magnetic moment of the ¹⁷C ground state. The distinctly small value of the g-factor obtained, |g(¹⁷C)|=0.5054±0.0025, clearly excludes a I ^π=1/2⁺ candidate for the spin-parity assignment of this marginally bound nucleus, providing a reasonable account of the non-halo nature reported in recent breakup reaction experiments. Finally, future plans at the upcoming radioactive beam facility presently under construction at RIKEN are briefly mentioned. This revised version was published online in September 2006 with corrections to the Cover Date.     

First beams and experiments at the nuclotron

The new heavy ion superconducting synchrotron - Nuclotron was put into operation and the pilot physics results on relativistic nuclear collisions were obtained.     

核物理与核探测、核分析技术的应用

文章概要介绍了随着核物理研究发展起来的辐射和粒子探测的原理、方法和主要技术,举例介绍了相关核物理与核探测、核分析的典型技术及其在高精度测量和医学中的广泛应用,如活化分析技术、穆斯堡尔谱学、核磁共振技术、加速器质谱技术、核医学成像、同步辐射技术、中子散射分析、放射性示踪技术等等.     

28.7MeV/u的 14，16，18 O+7，9Be反应中的同位素分布研究

用同位旋相关的Boltzmann-Langevin方程研究了在入射能量为28.7MeV/u下,不同弹核^14O,^16O和^18O轰击不同靶核^7Be和^9Be的反应,计算了生成碎片的产生截面,发现用丰中子（缺中子）炮弹或丰中子（缺中子）靶进行反应,所得到的产物均有丰中子（缺中子）的碎片出现。同位素分布宽度和峰位与入射体系密切相关,产生碎片的电荷数越接近入射弹核的电荷数,则同位素分布的宽度越大,峰位偏离β稳定线值越远,其同位旋效应越明显。。     

核物理与工农业发展

核物理应用主要包括核分析技术、同位素技术和离子束技术的应用,这些应用在工农业生产中发挥着巨大作用.离子束、电子束和同位素辐射源被广泛应用于辐照探伤、辐照加工、辐照消毒、辐照育种、辐照杀虫、辐照保藏等方面.核物理应用新技术将成为人类生活中重要的组成部分,正确认识核辐射并掌握基本的辐射防护知识具有重要意义.文章介绍了核物理在工业和农业中的应用及其社会效益和经济效益.     

核物理与工农业发展

核物理应用主要包括核分析技术、同位素技术和离子束技术的应用,这些应用在工农业生产中发挥着巨大作用.离子束、电子束和同位素辐射源被广泛应用于辐照探伤、辐照加工、辐照消毒、辐照育种、辐照杀虫、辐照保藏等方面.核物理应用新技术将成为人类生活中重要的组成部分,正确认识核辐射并掌握基本的辐射防护知识具有重要意义.文章介绍了核物理在工业和农业中的应用及其社会效益和经济效益.     

碎裂反应和放射性核束的产生

本总结了中能重离子碰撞产生同位素分布的计算方法和模型,包括参数化公式,擦碎模型和统计擦碎模型。介绍了模型的物理基础和计算方法,并讨论了对擦碎模型和统计擦碎模型的修正。同时用统计擦碎模型探讨了碎裂瓜在产生的同位素分布的同位旋效应。然后介绍了放射性核束的产生方法,并对放射性束流物理的发展前景作了简要介绍。