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恒星能量下俘获截面非常难于直接测量.因此,通常借助于非直接方法或从最低能量下的实验数据外推到天体物理感兴趣能区.首先证明了用渐近归一化常数方法得到的结果近似与模型无关.因此,转移反应的渐近归一化常数方法处理提供了一可靠的途径用以确定恒星能量下的俘获截面. 鉴于此优点, 用渐近归一化常数方法计算了10Be(n,γ)11Be反应的俘获截面. 11Be是一个众所周知的具有两弱束缚态的晕核.作为一个典型的例子,演示了俘获到晕态的辐射俘获截面明显增大, 证明了入射中子波函数与晕的伸展尾部有较大重叠是俘获截面异常增大的原因. 相似文献
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Zhang HuanQiao Lin ChengJian Jia HuiMing Zhang ChunLei Zhang GaoLong Yang Feng Liu ZuHua An GuangPeng Wu ZhenDong Xu XinXing Jia Fei 《中国科学:物理学 力学 天文学(英文版)》2011,54(1):6-13
The angular distributions of fission fragments for the 32S+184W reaction near Coulomb barrier energies are measured. The experimental fission excitation function is obtained. The measured fission cross sections are decomposed into fusion-fission, quasi-fission and fast fission contributions by the dinuclear system (DNS) model. The hindrance to completing fusion both at small and large collision energies is explained. The fusion excitation functions of 32S+90,96Zr in an energy range from above to below the Coulomb barrier are measured and analyzed within a semi-classical model. The obvious effect of positive Q-value multi-neutron transfers on the sub-barrier fusion enhancement is observed in the 32S+96Zr system. In addition, the excitation functions of quasi-elastic scattering at a backward angle have been measured with high precision for the systems of 16O + 208Pb, 196Pt, 184W, and 154,152Sm at energies well below the Coulomb barrier. Considering the deformed coupling effects, the extracted diffuseness parameters are close to the values extracted from the systematic analysis of elastic and inelastic scattering data. The elastic scattering angular distribution of 17F+12C at 60 MeV is measured and calculated by using the continuum-discretized coupled-channels (CDCC) approach. It is found that the diffuseness parameter of the real part of core-target potential has to be increased by 20% to reproduce the experimental result, which corresponds to an increment of potential depth at the surface region. The breakup cross section and the coupling between breakup and elastic scattering are small. 相似文献
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LIN ChengJian XU XinXing JIA HuiMing YANG Feng JIA Fei WU ZhenDong ZHANG ShiTao LIU ZuHua ZHANG HuanQiao XU HuShan SUN ZhiYu WANG JianSong HU ZhengGuo WANG Meng CHEN RuoFu ZHANG XueYing LI Chen LEI XiangGuo XU ZhiGuo XIAO GuoQing & ZHAN WenLong China Institute of Atomic Energy P. O. Box Beijing China 《中国科学:物理学 力学 天文学(英文版)》2011,(Z1)
Two-proton emissions from the excited states of 17,18Ne, 28P and 28,29S were investigated experimentally by the radioactive beams bombarding on the 197Au target via the Coulomb excitation. The complete-kinematics measurements were actualized by the stacks of silicon-strip detectors and CsI+PIN array detectors. The invariant mass of final systems as well as the relative momentum, opening angle, and relative energy of the two emitted protons was reconstructed under the framework of relativ istic kinematics. V... 相似文献
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ZHANG HuanQiao LIN ChengJian JIA HuiMing ZHANG ChunLei ZHANG GaoLong YANG Feng LIU ZuHua AN GuangPeng WU ZhenDong XU XinXing & JIA Fei China Institute of Atomic Energy P. O. Box Beijing China Particle Astrophysics Center 《中国科学:物理学 力学 天文学(英文版)》2011,(Z1)
The angular distributions of fission fragments for the 32S+184W reaction near Coulomb barrier energies are measured. The ex perimental fission excitation function is obtained. The measured fission cross sections are decomposed into fusion-fission, quasi-fission and fast fission contributions by the dinuclear system (DNS) model. The hindrance to completing fusion both at small and large collision energies is explained. The fusion excitation functions of 32S+90,96Zr in an energy range from above to below the ... 相似文献
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The production of superheavy nuclei with Z=108-116 via hot fusion reactions of the neutron-rich projectiles with 238U target is systematically studied.The results show that the production cross sections of superheavy nuclei do not decrease monotonously as the atomic number Z increasing.The cross sections of the superheavy nuclei at Z = 112 and 115 are enhanced as compared with the whole Z-trend in synthesis of the superheavy nuclei,which clearly illustrates that the reactions with large negative Q-value and... 相似文献
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Lin ChengJian Xu XinXing Jia HuiMing Yang Feng Jia Fei Wu ZhenDong Zhang ShiTao Liu ZuHua Zhang HuanQiao Xu HuShan Sun ZhiYu Wang JianSong Hu ZhengGuo Wang Meng Chen RuoFu Zhang XueYing Li Chen Lei XiangGuo Xu ZhiGuo Xiao GuoQing Zhan WenLong 《中国科学:物理学 力学 天文学(英文版)》2011,54(1):73-80
Two-proton emissions from the excited states of 17,18Ne, 28P and 28,29S were investigated experimentally by the radioactive beams bombarding on the 197Au target via the Coulomb excitation. The complete-kinematics measurements were actualized by the stacks of silicon-strip detectors and CsI+PIN array detectors. The invariant mass of final systems as well as the relative momentum, opening angle, and relative energy of the two emitted protons was reconstructed under the framework of relativistic kinematics. Visible proton-proton correlations were observed in these systems. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like 2He cluster emission, three-body phase-space decay, and two-body sequential decay were taken into account. With the help of Monte-Carlo simulations, the two protons emitted from the 6.15 MeV excited state of 18Ne and the excited states in the energy region of 9.6–10.4 MeV of 29S, respectively, exhibited prominent features of 2He cluster decay while for the other cases, no obvious diproton emissions were observed. 相似文献
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