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兰州重离子研究装置
No full text<正>1科学背景自从1932年劳伦斯建成世界上第一台回旋加速器起,物理学方面的重大成果越来越多地出自于大科学装置,上世纪许多获得诺贝尔物理奖的成果就是基于大科学装
Circumstantial Evidence for a Soft Nuclear Symmetry Energy at Suprasaturation Densities
No full textWithin an isospin- and momentum-dependent hadronic transport model, it is shown that the recent FOPI data on the pi(-)/pi(+) ratio in central heavy-ion collisions at SIS/GSI energies [Willy Reisdorf , Nucl. Phys. A 781, 459 (2007)] provide circumstantial evidence suggesting a rather soft nuclear symmetry energy E-sym(rho) at rho >= 2 rho(0) compared to the Akmal-Pandharipande-Ravenhall prediction. Some astrophysical implications and the need for further experimental confirmations are discussed.National Natural Science Foundation of China 10675148
10575071
10675082
MOE of China NCET-05-0392
Shanghai Rising-Star Program 06QA14024
SRF for ROCS
SEM of China
National Basic Research Program of China (973 Program) 2007CB815004
US National Science Foundation PHY-0652548
PHY-0757839
Research Corporation 7123
Texas Coordinating Board of Higher Education 003565-0004-200
Study of the interaction of highly charged ions with SiO2 surface
No full textHighly charged ions (HCIs) AO(q+)/Pbq+ are extracted from ECR source and impacted on solid surface Of SiO2 Sputtering yield as a function of incident angle is measured by multi-channel plate (MCP). The results have been fitted by a new formula. We proposed the cooperation model to explain the formula. The results demonstrate that the potential assisted kinetic sputtering yield increases with the charge state and potential sputtering (PS) could be induced by impact of HCIs. At larger incident angles, the sputtering yield is dominated by elastic collision between HCIs and material atoms. It is found that, smaller the incident angle, larger the contribution from the potential sputtering. (C) 2009 Elsevier B.V. All rights reserved
Modification of Fe/Cu Multilayers under 2-MeV Xe20+ Irradiation
No full textMultilayers with a structure of Si/[Fe(10 nm)/CU(10 nm)](5) were deposited on Si(100) substrates and then irradiated at room temperature by using 2-MeV Xe20+. The modifications of the multilayers were characterized using a depth profile analysis of the Auger electron spectroscopy (AES) data and the evolution of crystallite structures of the multilayers were analyzed by using X-ray diffraction (XRD). The AES depth profiles indicated that de-mixing of the Fe and the Cu layers was observed at low ion fluences, but inter-mixing of the Fe and the Cu layers was found at high ion fluences and destroyed the layered structure of the multilayers. The obtained XRD patterns showed that, after irradiation by 2-MeV Xe20+ at; 2 x 10(16) ions/cm(2), the peaks of the multilayers related to a Cu-based fee solid solution and an Fe-based bee solid solution phase became visible, which implied that the inter-mixing at the Fe/Cu interface resulted in the formation of new phases. A possible mechanism of modification in the Fe/Cu multilayers induced by ion irradiation is briefly discussed
Structural analysis of nickel doped cobalt ferrite nanoparticles prepared by coprecipitation route
No full textMagnetic nanoparticles of nickel substituted cobalt ferrite (NixCo1-xFe2O4:0 <= x <= 1) have been synthesized by co-precipitation route. Particles size as estimated by the full width half maximum (FWHM) of the strongest X-ray diffraction (XRD) peak and transmission electron microscopy (TEM) techniques was found in the range 18-28 +/- 4 nm. Energy dispersive X-ray (EDX) analysis confirms the presence of Co, Ni, Fe and oxygen as well as the desired phases in the prepared nanoparticles. The selective area electron diffraction (SAED) analysis confirms the crystalline nature of the prepared nanoparticles. Data collected from the magnetization hysteresis loops of the samples show that the prepared nanoparticles are highly magnetic at room temperature. Both coercivity and saturation magnetization of the samples were found to decrease linearly with increasing Ni-concentration in cobalt ferrite. Superparamagnetic blocking temperature as determined from the zero field cooled (ZFC) magnetization curve shows a decreasing trend with increasing Ni-concentration in cobalt ferrite nanoparticles. (C) 2009 Elsevier B.V. All rights reserved.National NSF of China 10775161
10775162
10805062
West Light Foundatio
Theoretical study on spherical proton emission
No full textThe proton radioactivity half-lives of spherical proton emitters are investigated within a generalized liquid drop model (GLDM), including the proximity effects between nuclei in a neck and the mass and charge asymmetry. The penetrability is calculated in the WKB approximation and the assault frequency is estimated by the quantum mechanism method considering the structure of the parent nucleus. The spectroscopic factor is taken into account in half-life calculation, which is obtained by employing the relativistic mean field (RMF) theory. The half-lives within the GLDM are compared with the experimental data and other theoretical values. The results show that the GLDM works quite well for spherical proton emitters when the assault frequency is estimated by the quantum mechanical method and the spectroscopic factor is considered.National Natural Science Foundation of China 10775061
10805016
Fundamental Research Fund for Physics and Mathematics of Lanzhou University LZULL200805
CAS Knowledge Innovation KJCX-SYW-N02
Major State Basic Research Developing Program of China 2007CB81500
Doubly excited 2s2p P-1,3(1) resonances in photoionization of helium
No full textThe multi-configuration Dirac Fock (MCDF) method is implemented to study doubly excited 2s2p P-1,3(1) resonances of the helium atom and the interference between photoionization and photo excitation autoionization processes. In order to reproduce the total photoionization sprectra, the excited energies from the ground 1s(2) S-1(0) state to the doubly excited 2s2p P-1,3(1) states and the relevant Auger decay rates and widths are calculated in detail. Further more, the interference profile determined by the so-called Fano parameters q and rho(2) is also reproduced. Good agreement is found between the present results and other available theoretical and experimental results. This indeed shows a promising way to investigate the Fano resonances in photoionization of atoms within the MCDF scheme, although there are some discrepancies in the present calculations of the 2s2p P-3(1) state.ational Natural Science Foundation of China 10774122
10876028
China/Ireland Science and Technology Collaboration Research Fund CI-2004-07
Higher Education of China 20070736001
Foundation of Northwest Normal University of China NWNU-KJCXGC-03-2
Alpha decay half-lives of heavy nuclei within a generalized liquid drop model
No full textTheoretical alpha-decay half-lives of the heaviest nuclei are calculated using the experimental Q value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the Density-Dependent, M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the a decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time.Natural Science Foundation of China 10775061
10505016
1057511
Structure and orientation effects involved in the dynamics of hydrogen molecular ion on helium collisions
No full text在原子分子碰撞实验中，反应显微成像谱仪技术可以实现对碰撞产物的动力学完
全测量。本论文基于中科院近物所 320 kV 高电荷态离子综合研究平台与德国马普核物
理所串列加速器上搭建的反应显微成像谱仪，研究了 0.15 MeV和1 MeV氢分子离子与
氦原子碰撞中电离激发通道对应的分子取向和结构效应。该工作在世界上首次实现了
高能（1 MeV）分子离子的取向定位。
实验数据表明，靶原子的出射电子、反冲离子以及碰撞过程中的动量转移都受到
分子结构的影响。在垂直于束流线的平面内，这些相对应过程的截面分布极大值位置
都出现在碰撞时刻分子轴方向上。在分子轴与束流方向建立的平面内，这些截面随分
子轴方向变化的规律各不相同：其中电离截面和反冲离子出射截面的大小以及极大值
位置都会随着分子轴方向的变化而变化；靶原子的散射截面（对应动量转移过程）只
有截面大小随着分子轴方向的变化而变化，截面极大值位置并不随之改变。
实验数据分析发现在碰撞过程中氦原子的物质波在氢分子的双中心结构上的干涉，
并且在干涉条纹中观测到由于氢分子离子激发态宇称不同而导致的干涉条纹的相位翻
转的现象。这些现象与量子力学理论结果符合得非常好。
本论文工作为研究与分子取向和结构相关的物理过程奠定了实验和分析基础；同
时为实验确定高能分子结构和取向提供了一种思路；研究证明了分子的取向与分子结
构是碰撞过程中重要的物理参量；同时该工作第一次发现了碰撞中由于宇称不同导致
干涉条纹发生变化的现象，为我们研究宇称提供了一种的新思路
Transfer Ionization Mechanism in Low-Intermediate Energy He2+on He Collision
No full text反应显微成像谱仪能够对离子-原子碰撞反应中的末态产物进行运动学完全测量。
本论文基于反应显微成像谱仪对 70-400keV He2+ -He碰撞中转移电离机制进行了实验研
究。
通过对不同出射角度电子的能谱研究表明， ECC电子和速度分布在 0和入射炮弹速
度之间的“分子化”特征电子是出射电子能谱的主要贡献，前者是动力学两步过程的作
用，后者可由“准分子”激发模型给予定性解释， “鞍点电子”仅是后者的一部分。通
过对不同平面内出射电子的速度分布研究发现出射电子主要集中在散射平面内，而且其
速度分布介于0与炮弹速度之间且前向出射，同时在炮弹与靶核核间轴处有一极小值；
在入射离子能量较低时，出射电子空间分布较为对称，随着入射离子能量的增加，出射
电子逐渐靠近炮弹或靶核；与此同时，由于σ态电子与π态电子相互干涉，出射电子在散射
平面内的分布还与碰撞参数相关，在大碰撞参数下,σ态电子的作用更加明显，而
在小碰撞参数下π态电子的作用更加显著。实验结果表明准分子激发和动力学两步过程
是中低能He2+-He转移电离过程的两种主要机制