Identification of new isotopes below argon completed by Artukh et al and the synthesis of new heavy neutron-rich nuclides at the GSI demonstrated that the multi-nucleon transfer reactions are a very suitable tool for ...Identification of new isotopes below argon completed by Artukh et al and the synthesis of new heavy neutron-rich nuclides at the GSI demonstrated that the multi-nucleon transfer reactions are a very suitable tool for the production of new neutron-rich nuclides. The results of the synthesis and identification for new heavy neutron-rich isotopes 208-209Hg, 239pa, 186Hf and 238Th at IMp show also multi-nucleon transfer展开更多
天体环境中丰中子核素熔合反应率对研究中子星表面超级暴现象的点火机制有重要意义。由于次级束流强过低,无法使用传统固体靶实验技术测量垒下熔合反应截面。活性靶技术的发展为垒下丰中子核素熔合反应截面的测量提供了可行的途径。基于...天体环境中丰中子核素熔合反应率对研究中子星表面超级暴现象的点火机制有重要意义。由于次级束流强过低,无法使用传统固体靶实验技术测量垒下熔合反应截面。活性靶技术的发展为垒下丰中子核素熔合反应截面的测量提供了可行的途径。基于Geant4模拟详细地分析了多重采样电离室(MUSIC)与时间投影室(TPC)两种活性靶探测器中熔合反应与弹性散射的运动学性质,给出了4种熔合反应鉴别判据,并且计算了由这些判据误判引起的熔合截面系统误差。在Ecm=13.6 Me V时,MUSIC与TPC的弹性散射误判截面分别为0.5 mb和2.9×10^(-3)mb,都远小于此时熔合截面(877 mb)。在垒下,MSUIC的熔合截面系统误差已经超出实验测量要求,而TPC能够进行实验测量的能量可以降低至Ecm=4.7 Me V。展开更多
Recent experiments open up the possibility to investigate oblate rotation-aligned states and prolate high-K isomers in neutron-rich tungsten isotopes.In the present work,we perform the projected-shell-model calculatio...Recent experiments open up the possibility to investigate oblate rotation-aligned states and prolate high-K isomers in neutron-rich tungsten isotopes.In the present work,we perform the projected-shell-model calculations for A ～ 190 tungsten nuclei.The 190 W results are compared with experimental data.The observed 8 + isomer is assigned as a two-quasiproton K π = 8 + configuration.Low-lying high-K four-quasiparticle states are predicted.Of particular interest is the prediction of the K π = 20 + state in 190,192 W,which may form a long-lived spin trap.In competition with the prolate high-K states,rotational alignment leads to near-yrast collective oblate rotation.展开更多
Pairing-deformation-frequency self-consistent cranking Woods-Saxon model is employed to investigate the triaxiality in the ground states of the neutron-rich even-even Mo, Ru isotopes. Deformation evolutions and transi...Pairing-deformation-frequency self-consistent cranking Woods-Saxon model is employed to investigate the triaxiality in the ground states of the neutron-rich even-even Mo, Ru isotopes. Deformation evolutions and transition probabilities have been studied, giving the triaxial shapes in their ground states. The kinematic moments of inertia have been calculated to illustrate the gradually rigid deformation. To understand the origin of the asymmetry shape in this region, we analyze the evolution of single-particle orbits with changing 3, deformation. The present calculations reveal the importance of the triaxial deformation in describing not only static property, but also rotational behaviors in this mass region, providing significant probes into the shell structure around.展开更多
The heavy elements in the Universe are formed during the s- and r-processes mainly in AGB stars and supernovae, respectively. Simulation of s- and r-nucleosynthesis critically depends on the neutron capture and weak d...The heavy elements in the Universe are formed during the s- and r-processes mainly in AGB stars and supernovae, respectively. Simulation of s- and r-nucleosynthesis critically depends on the neutron capture and weak decay rates for all the nuclei on the reaction chain. The present work analyzes systematically the neutron capture rates (cross sections) for the s-process nuclei, including ～3000 rates on ～200 nuclei. The network calculations for the constant temperature s-process have been performed using the different data sets selected as the nuclear inputs to investigate the uncertainties in the predicted s-abundances. We show that the available cross sections of neutron capture on many s-process nuclei still carry large uncertainties, which lead to low accuracy in the determination of s-process isotope abundances. We analyze the neutron capture cross section data for the same unique isobar nucleus accorded by year from previous work. Such an analysis indicates that the s-process has been studied for more than fifty years and there exist two research stages around 1976 and 2002, respectively. The needs and opportunities for future experiments and theoretical tools are highlighted to remove the existing shortcomings in the neutron capture rates.展开更多
文摘Identification of new isotopes below argon completed by Artukh et al and the synthesis of new heavy neutron-rich nuclides at the GSI demonstrated that the multi-nucleon transfer reactions are a very suitable tool for the production of new neutron-rich nuclides. The results of the synthesis and identification for new heavy neutron-rich isotopes 208-209Hg, 239pa, 186Hf and 238Th at IMp show also multi-nucleon transfer
文摘天体环境中丰中子核素熔合反应率对研究中子星表面超级暴现象的点火机制有重要意义。由于次级束流强过低,无法使用传统固体靶实验技术测量垒下熔合反应截面。活性靶技术的发展为垒下丰中子核素熔合反应截面的测量提供了可行的途径。基于Geant4模拟详细地分析了多重采样电离室(MUSIC)与时间投影室(TPC)两种活性靶探测器中熔合反应与弹性散射的运动学性质,给出了4种熔合反应鉴别判据,并且计算了由这些判据误判引起的熔合截面系统误差。在Ecm=13.6 Me V时,MUSIC与TPC的弹性散射误判截面分别为0.5 mb和2.9×10^(-3)mb,都远小于此时熔合截面(877 mb)。在垒下,MSUIC的熔合截面系统误差已经超出实验测量要求,而TPC能够进行实验测量的能量可以降低至Ecm=4.7 Me V。
基金supported by the National Natural Science Foundation of China (Grant No. 10975006)
文摘Recent experiments open up the possibility to investigate oblate rotation-aligned states and prolate high-K isomers in neutron-rich tungsten isotopes.In the present work,we perform the projected-shell-model calculations for A ～ 190 tungsten nuclei.The 190 W results are compared with experimental data.The observed 8 + isomer is assigned as a two-quasiproton K π = 8 + configuration.Low-lying high-K four-quasiparticle states are predicted.Of particular interest is the prediction of the K π = 20 + state in 190,192 W,which may form a long-lived spin trap.In competition with the prolate high-K states,rotational alignment leads to near-yrast collective oblate rotation.
基金supported by the National Key Basic Research Program of China(Grant No.2013CB834402)the National Natural Science Foundation of China(Grant Nos.11235001,11320101004 and 11575007)
文摘Pairing-deformation-frequency self-consistent cranking Woods-Saxon model is employed to investigate the triaxiality in the ground states of the neutron-rich even-even Mo, Ru isotopes. Deformation evolutions and transition probabilities have been studied, giving the triaxial shapes in their ground states. The kinematic moments of inertia have been calculated to illustrate the gradually rigid deformation. To understand the origin of the asymmetry shape in this region, we analyze the evolution of single-particle orbits with changing 3, deformation. The present calculations reveal the importance of the triaxial deformation in describing not only static property, but also rotational behaviors in this mass region, providing significant probes into the shell structure around.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11021504, 11175258, 11275068 and 11175001)the Major State Basic Research Development Program of China (Grant No.2013CB834406)
文摘The heavy elements in the Universe are formed during the s- and r-processes mainly in AGB stars and supernovae, respectively. Simulation of s- and r-nucleosynthesis critically depends on the neutron capture and weak decay rates for all the nuclei on the reaction chain. The present work analyzes systematically the neutron capture rates (cross sections) for the s-process nuclei, including ～3000 rates on ～200 nuclei. The network calculations for the constant temperature s-process have been performed using the different data sets selected as the nuclear inputs to investigate the uncertainties in the predicted s-abundances. We show that the available cross sections of neutron capture on many s-process nuclei still carry large uncertainties, which lead to low accuracy in the determination of s-process isotope abundances. We analyze the neutron capture cross section data for the same unique isobar nucleus accorded by year from previous work. Such an analysis indicates that the s-process has been studied for more than fifty years and there exist two research stages around 1976 and 2002, respectively. The needs and opportunities for future experiments and theoretical tools are highlighted to remove the existing shortcomings in the neutron capture rates.
