超重核合成进展

介绍了超重核合成的历史和现状,对现有的超重核合成的实验情况和理论模型做了评述,指出了在国内利用现有设备和放射性核束装置开展超重核合成可能的方案。     

核天体物理中的核结构问题

核结构信息在星体的演化和爆炸以及宇宙元素生成的研究中起着极重要的作用. 原子核基态性质(如质量、寿命、衰变分支), 特别是不稳定核的性质, 可以定性地和定量地改变天体物理模拟的预言. 远离稳定线粒子滴线的位置和壳结构也会强烈地影响天体物理的预言. 举几个例子说明新的核结构信息对于新星、X射线爆和核芯塌缩超新星的戏剧性影响. 其中的某些方面来自于橡树岭实验室放射性离子束设备上的¹⁸F, ⁸²Ge和⁸⁴Se放射核束的最新实验测量结果. 同时展示新一套软件工具如何帮助确定核物理研究对于天体物理的影响.     

核结构的新机遇

讨论核结构的新机遇及其发展特点.着重从大型实验设备和技术的革命性进步的角度,阐明核结构的新机遇和发展的坚实基础和保证.     

天体物理中爆发性核合成

简要地评述天体核过程,着重讨论爆发性氢燃烧过程,并利用最新的反应率实验数据对氢燃烧过程进行了计算.指出从热pp链通过¹¹C的质子辐射俘获反应进入CNO循环的反应流量可以超过3α过程的流量.用¹⁸F(p,γ)和(p,α)反应的新反应率计算的¹⁸F生成丰度比旧反应率给出的丰度要大1.8倍.对在X射线爆的典型天体物理条件下的快质子(rp)过程的计算表明,“等待核”⁸⁹Ru和⁹³Pd的β衰变寿命的新实验数据给出的该2核的生成丰度,比旧实验数据给出的值要大4倍.     

超重核合成进展

介绍了超重核合成的历史和现状 ,对现有的超重核合成的实验情况和理论模型做了评述 ,指出了在国内利用现有设备和放射性核束装置开展超重核合成可能的方案     

放射性核束(RIB)的物理前沿

介绍了世界上主要的放射性核束装置,并对当前放射性核束物理研究的前沿方向作了评述．同时,也展望了放射性核束装置的发展趋势．Several Radioactive Ion Beam (RIB) lines are briefly introduced in this paper, and the main frontier fields of RIB physics are reviewed.In the last section,the developing trends of RIB setup are prospected.      

逆运动学弹性共振散射方法在非束缚核结构研究中的应用

简要介绍了近几年发展起来的厚靶逆运动学弹性共振散射方法在非稳定核结构测量中的应用。它是研究非束缚态核结构的实验方法之一。通过测量反冲轻核的激发函数，提取共振态的能量、自旋宇称和衰变宽度等。主要用于研究非稳定核素的结构、核天体物理中相关核的阈能共振态的能级参数测量等。The method of elastic resonance scattering in inverse kinematics, which was progressed in recent years, is briefly introduced. It is a novel experimental technique to perform meaningful experiments under conditions of the very short-lived nuclides and the beam intensities only 1 000 atoms/s. The excitation function of recoil proton has been measured in experiment; the shape of proton energy spectrum can be also used to uniquely deter- mine the energy of resonant states, spin-parity, partial decay width and spectroscopic factors of the states. This method is mainly used in the investigation of unstable nuclei and the level parameters measurement of near threshold resonant state of the nuclear astrophysics related nuclei.     

BRISOL铝同位素放射性核束的产生

北京放射性核束装置在线同位素分离器(BRISOL)采用100 MeV回旋加速器提供的最大200μA的质子束打靶在线产生放射性核束。在BRISOL上已经使用氧化钙靶、氧化镁靶产生了Na⁺、K⁺等放射性核束。为了产生铝同位素放射性核束,研发了碳化硅靶材,开展了碳化硅靶产生铝放射性核束的实验研究。在BRISOL装置上首次产生了铝同位素放射性核束,其中^26gAl⁺的束流强度为8.7×10⁷ pps,²³Al⁺的束流强度为2.2×10² pps,同时将BRISOL靶能承受的质子束流强提升至15。     

Nuclear Masses and the r- and p-Processes of Nucleosynthesis

Although important efforts have been devoted in the last decades to measure atomic masses, the modelling of the r- and p-processes of nucleosynthesis still requires the use of theoretical predictions to estimate experimentally unknown masses in the neutron-rich and neutron-deficient regions. Different mass models are available to extrapolate nuclear masses far away from the experimentally known region. These models are compared and used to estimate the reaction rates of relevance in the r- and p-processes. The impact of the different mass models on the astrophysics predictions are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nucleosynthesis Without Computer

Complete analytical derivation of the time evolution and final abundances of the light elements (up to ⁷Be) formed in the big-bang nucleosynthesis is presented. This highlights an interesting physics taking place during the formation of light elements in the early universe.     

元素核合成

简单介绍了元素的核合成理论发展的历史和现况．The development history of the nucleosynthesis theory of elements, which was presented by E. M. Burbidge. G. R. Burbidge, W. A. Fowler, F. Hoyle and A. G. W.Cameron, and the progress of this theory during the past 40 years are introduced.     

Nucleosynthesis in thermonuclear supernovae

We review our understanding of the nucleosynthesis that occurs in thermonuclear supernovae and their contribution to Galactic Chemical evolution. We discuss the prospects to improve the modeling of the nucleosynthesis within simulations of these events.     

Three-Frequency Composite Multipulse Nuclear Quadrupole Resonance Technique for Explosive Detection

New method of multifrequency nuclear quadrupole resonance (NQR) for the explosive detection has been proposed. This technique consists of application of the series of composite excitation circles, each consisting of two or three successive pulses of different frequencies. In this work, we study in detail the multipulse sequence consisting of n excitation sets, each set consists of three pulses. The first pulse is applied with frequency ?? _?, the second pulse with frequency ?? ₀, and the third pulse with frequency ?? _?C, but with a shifted phase. The NQR signal is detected at the frequency ?? ₊. The maximal amplitude of the detected signal is obtained by tuning the pulse parameters at frequencies ?? _? and ?? ₀. We have shown that the phase of the NQR signal at the frequency ?? ₊ second part of the composite pulse with the frequency ?? ₀ the signals with different phases to suppress the spurious signals. The method could be used for increasing the NQR signal, avoiding the spurious signals and improving the reliability of NQR detection. Possible applications of the method for the explosive detection are also discussed.     

方形爆炸抛撒装置结构优化

为了研究方形抛撒装置壳体破坏规律及燃料分散特性,开展了抛撒装置外场实验并利用LS-DYNA仿真软件进行了数值模拟,模拟结果与实验结果相吻合。进一步分析装置倒圆角及刻槽深度对壳体破裂效果及燃料分散速度的影响规律,结果表明:倒圆角与增加刻槽深度有利于减小壳体棱边处应力集中的影响,圆角半径增至10 mm或刻槽深度增至1.2 mm时,棱边处不再破裂;同一装置壳体边部和中部位置采用不同深度的刻槽可有效减少壳体破裂不均现象。当边缘处刻槽深度为1.2 mm、中间刻槽为1.6 mm时,壳体均匀破裂;当棱边处倒10 mm圆角,边部刻槽深度为0.8 mm,中部刻槽为1.2 mm时,抛撒装置既能满足壳体均匀开裂,又可提高壳体强度,同时可将燃料分散平均速度差值降低22%,从而有效提高燃料抛撒效率。     

Large-Scale Shell Model for Nuclear Structure and Nuclear Astrophysics Studies

The study of neutron-rich nuclei near 132Sn is interesting and important for both nuclear  structure and nuclear astrophysics. For a considerably large model space allowing cross-shell excitations, a new effective Hamiltonian is determined by employing the extended pairing-plus-quadrupole model with monopole corrections. Calculations for two mass regions, for the north-east quadrant of 132Sn with Z > 50 and N > 82 and for the south-west quadrant with Z < 50 and N < 82, have been performed recently. The structure of these nuclei is analyzed in detail, and the role of the monopole corrections canbe clearly seen.