Applications of Skyrme Energy-Density Functional to Fusion Reactions for Synthesis of Superheavy Nuclei

It is of great importance to predict fusion cross sections and to analyze reaction mechanism for massive heavy-ion fusion reactions, especially for fusion reactions leading to superheavy nuclei. In those reactions, the calculation of the capture cross section is of crucial importance. It is known that Wong＇s formula based on one-dimensional barrier penetration can describe the fusion excitation function well for light reaction systems, while it fails to give satisfying results for heavy reaction systems at energies near and below the barrier. For solving this problem, we applied the Skyrme energy-density functional for the first time to study heavy-ion fusion reactions. The barrier for fusion reaction was calculated by the Skyrme energy-density functional together with the semi-classical extended Thomas-Fermi method.     

Applications of Skyrme Energy-Density Functional to Fusion Reactions Spanning Fusion Barriers

对于重核的壳模型计算，一种可能的方案是采用变形基和投影技术。这里给出投影壳模型的一个新发展。本工作以三轴形变多准粒子组态为起点，通过三维角动量投影，构造出壳模型空间，将哈密顿量在该空间内对角化。这一新理论使我们对旋称反转这一旧问题产生了新的认识。通过130核区实验的很好再现（图1，2），我们认为，旋称反转是由于在三轴形变情况下，原子核的转动轴相对于内禀坐标系发生了动态漂移。质子中子相互作用以及四极对力仅改变旋称反转的细节而不起重要作用。     

Applications of Skyrme Energy-Density Functional to Fusion Reactions Spanning Fusion Barriers

在加速器驱动次临界系统（ADS）项目中，由我院承担研制的强流RFQ注入系统，包括ECR强流离子源及束流低能传输线（LEBT），从2005年8月移机中国科学院高能物理研究所后，历时半年多时间，解决了由于工作环境改变而带来的一系列水、电、气问题，包括电器系统供电与控制的改造，     

Origin of Unexpected Isotopic Trends in Synthesis of Superheavy Nuclei

Synthesis of the superheavy elements （SHE） is a topic of great interest in nuclear physics. Up to now the region of the ＂island of superheavy nucleus＂ is extended up to element Z= 118 using the 48Ca-induced hot fusion reactions with actinide targets. However, the superheavy nuclei synthesized nowadays are all in the proton-rich side of the ＂superheavy island＂. In order to reach the center region of the ＂island of superheavy nucleus＂,     

Optimal Reactions for Synthesis of Superheavy Nucleus ^270Hs

The macroscopic-microscopic approach predicts a strong proton-deformed shell at Z=108 to be a partner for the neutron shell at N=162. Thus the nucleus ^270Hs is expected to be a relatively strongly bound ＂double-magic＂ deformed nucleus. Therefore, it is of great interest to synthesize the nucleus 27~Hs and to investigate its structure experimentally. However,     

Q-Value Effects on Production of Superheavy Nuclei

The yields of superheavy nucleus ^270Hs via 4n evaporation channel of fusion reactions ^26Mg＋^248Cm, ^30Si＋^244Pu, ^36S＋^238U and ^48Ca＋^226Ra are studied using a two-parameter Smoluchowski equation.     

Statistical Behavoirs of Quantum Spectra in Superheavy Nuclei

From the point of view of the interplay between order and chaos, the most regular single-particle motion of neutrons has been found in the superheavy system of Z=120 and N=184 based on the Skyrme-Hartree-Fock model and in the system of Z=120 and N=12 based on the relativistic mean-field model. It has been shown that the statistical analysis of spectra indeed can give very valuable information about the stability of superheavy systems. The significance of this kind of study can go far beyond the investigation on the stability of superheavy systems and it may give a deep     

Nonelectric Applications of Fusion

This is the final report of a panel set up by the U.S. Department of Energy (DOE) Fusion Energy Sciences Advisory Committee (FESAC) in response to a charge letter from Dr. James Decker, Acting Director of the DOE Office of Science. In that letter, Dr. Decker asked FESAC to consider whether the Fusion Energy Sciences program should broaden its scope and activities to include non-electric applications of intermediate-term fusion devices. This report, submitted to FESAC July 31, 2003, and subsequently approved by them (Appendix B), presents FESAC's response to that charge.     

Investigation in Possibility of Producing Superheavy Fragments Through Massive Nuclear Reactions at Low Energies

In this paper, the possibility of producing superheavy fragments through composite system breaking up in massive nuclear reactions is investigated. Two main theoretical models, which are the quantum fluctuations within the fragmentation theory developed at 80 years and improved quantum molecular dynamics model developed recently by our group,     

A Silicon Detector Array for Study of Breakup Reactions of Weakly Bound Nuclei

<正>Reaction mechanism study of weakly bound nuclei is one of the hot topics of nuclear physics.To get better result in the breakup reaction study of weakly bound nuclei at energies near the coulomb barrier,a new multilayer ΔE-E_R telescope array with large solid angle and high position resolution was designed and manufactured.     

利用镜像核转移反应研究短寿命不稳定核(p,γ)反应

介绍利用中子转移反应和镜像核的电荷对称性来间接研究丰质子核的(p,γ)反应。该方法有助于更充分地利用北京HI-13串列加速器次级束流线(GIRAFFE)上现有次级束流，拓宽其实验研究范围，间接得出质子辐射俘获截面（或反应率）且减小其不确定性（相对于已有数据）。在GIRAFFE上利用逆运动学测量了⁸Li(d,p)⁹Li反应的角分布，通过该方法间接确定了天体物理重要反应⁸B(p,γ)⁹C的直接俘获贡献。作为不同于以往的方法，给⁸B(p,γ)⁹C反应的现有研究结果提供了一独立的交叉检验。分析²⁶Mg(d,p)²⁷Mg反应基态、第一、第二激发态的角分布，间接确定²⁶Si(p,γ)²⁷P反应的直接和共振俘获贡献，首次从实验上导出²⁶Si(p,γ)²⁷P反应的直接俘获贡献。此方法也可以用于其它一系列重要的天体物理反应的研究。     

Study on Quantum Coupled-channels Model for Heavy-ion Fusion Reactions

<正>The study of heavy-ion fusion reactions is of great importance in many aspects of nuclear physics.Solving the adiabatic coupled-channelsequation is one of the standard approaches to investigate nuclear fusion reactions.The stable and high-accuracy numerical solution of the     

Examination of Various Kinds of Systematics of Double-Differential Particle Emission Cross Sections for Medium-Heavy Nuclei Important to Fusion Neutronics

Various kinds of systematics used to calculate the double-differential light particle emission cross sections from nuclear reactions induced by light particles are examined for medium-heavy nuclei important in fusion neutronics applications. Fixing the incident and outgoing particles to neutrons, and the incident energy at 14 MeV, results calculated by the systematics, supplemented by the statistical model calculation, are compared with experimental data measured by two Japanese groups. It is concluded that systematics derived by Kumabe et at. and Kalbach has good accuracy in reproducing these data. Discrepancies in the experimental data are pointed out, and suggestions to future compilation of a special purpose file of JENDL for fusion neutronics are made.     

Symmetric Neutralized Ion Beams for Magnetic Fusion Applications

A symmetric neutralized ion beam (SNIB) is composed of positive and negative ions, and is capable of propagating across a transverse magnetic field due to the polarization of the beam. Such a beam may be of use as an alternative or complement to conventional neutral beam injection (NBI) in magnetic confinement fusion devices. SNIBs of energies from hundreds of keV up to a few MeV can be efficiently produced through a novel application of radio frequency quadrupole (RFQ) accelerators. Because the cross-field propagation ability of the SNIB depends mainly on beam density, SNIBs of significantly lower energy than the 1 MeV envisioned for ITER neutral beams can in principle reach the center of a magnetically confined plasma. Some challenges that need to be overcome for this technique to be viable are identified; nevertheless, the approach is attractive when compared to the bulky, high voltage, conventional neutral beam systems. Distributed injection of many beams is possible due to the relative compactness of a SNIB module.     

Thermal Shock Behavior of SiC Coatings for Fusion Reactor Applications

Graphite substrate ISEM-3 whose thermal expansion coefficient is close to that of SiC and graphite substrate AXF-5Q1 whose thermal expansion coefficient is larger than that of SiC were coated with 50–200 μm thick CVD-SiC. On the AXF-5Q1 graphite substrate SiC could not be completely coated. Additionally HSC-SiC, which has SiC conversion layer of 800 μm thickness and whose thermal expansion coefficient of the graphite substrate is close to that of SiC, was also tested. Thermal shock test was carried out by electron beam of accelerating voltage of 10 kV, beam current of 50–200 mA, beam diameter of about 10 mmø and heating time of a single pulse of 30 s. Crack was not observed on the CVD-SiC coating on the ISEM-3 graphite even at 200 mA (about 2.5kW/cm²) and hole of about 1 mm in diameter was observed and the graphite substrate was revealed. Additionally for thermal cycle test (1,000 times, ΔT=950°C), the crack or spalling was not observed on the CVD-SiC coating. It was found that for the HSC-SiC the hole was only observed with the single pulse of 200 mA and the crack was not observed. Thus the HSC-SiC also may be a candidate as the first wall of the fusion reactors.     

Neutron Response Calculations of Alpha-Track Detector for Fusion Neutronics Applications

The neutron energy dependent response of the α-track detector, cellulose nitrate film (Kodak LR-115 type I) in contact with a lithium radiator was calculated. The “mean effective thickness L _eff” of the radiator is obtained as a function of the neutron energy and incident angle. The distribution of the etched-through-track density is evaluated from the calculated L _eff and compared with the measured results in the fusion blanket assembly.     

超重元素合成实验靶室及转靶装置

文章介绍兰州重离子加速器放射性次级束流线（RIBLL）的超重元素合成实验靶室和转靶系统，并对改进的真空密封磁耦合传动机械作简单描述。转靶系统采用可程序控制的无级变速电机、真空密[JP2]封磁流体耦合和特殊皮带传动机构，使得靶盘转速在0~600r/min范围内可调，靶盘边缘摆幅＜0.2mm。     

Energy Dependence of Dynamic Barrier in Heavy-Ion Fusion Reactions

投影壳模型（PSM）给出的波函数具有好的角动量和宇称，并且不断证实它可以很好地描述原子核的多方面性质。本工作期望采用PSM波函数计算Beta衰变矩阵元能够给出较好的结果。最近，应用投影壳模型初步建立了Gamov—Teller（GT）跃迁的计算程序。