The structure of Ne isotopes has been investigated by using deformed Skyrme-Hartree-Fock （SHF） method and BCS approximation. Especially the effect of tensor force on the halo structure of 29Ne and 31Ne is discussed....The structure of Ne isotopes has been investigated by using deformed Skyrme-Hartree-Fock （SHF） method and BCS approximation. Especially the effect of tensor force on the halo structure of 29Ne and 31Ne is discussed. To this end, the tensor contributions are considered to the energy density function and the single particle potential in SHF theory. For comparison, four Skyrme interactions are used： SLy5 and SGII without tensor force, and SLy5＋T and SGII＋ T with tensor force. The results indicate that the inclusion of tensor force shows a more pronounced halo structure for 31Ne.展开更多
The properties of neutron-rich boron isotopes are studied in the relativistic continuum Hartree-Bogoliubov theory in coordinate space with NL-SH,PK1 and TM2 effective interactions.Pairing corrections are taken into ac...The properties of neutron-rich boron isotopes are studied in the relativistic continuum Hartree-Bogoliubov theory in coordinate space with NL-SH,PK1 and TM2 effective interactions.Pairing corrections are taken into account by a density dependent force of zero range.The binding energies calculated for these nuclei agree with the experimental data quite well.The neutron-rich nucleus 17 B has been predicted to have a two-neutron halo structure in its ground state.The halo structure of 17 B is reproduced in a self-consistent way,and this halo is shown to be formed by the valence neutron level 2s 1/2.展开更多
We used the star counts in 21 BATC fields obtained with the National Astronomical Observatories （NAOC） 60/90 cm Schmidt Telescope to study the structure of the Galactic halo. Adopting a de Vaucouleurs r1/4 law halo,...We used the star counts in 21 BATC fields obtained with the National Astronomical Observatories （NAOC） 60/90 cm Schmidt Telescope to study the structure of the Galactic halo. Adopting a de Vaucouleurs r1/4 law halo, we found that the halo is somewhat flatter （c/a - 0.4） towards the Galactic center than in the anticentre and antirotation direction （c/a 〉 0.4）. We also notice that the axial ratios are smaller （flatter） towards the low latitude fields than the high latitude fields, except for a few fields. We provide robust limits on the large-scale flattening of the halo. Our analysis shows that the axial ratio of the halo may vary with distance and the observation direction. At large Galactocentric radii, the halo may not have a smooth density distribution, but rather, it may be largely composed of overlapping streams or substructures, which provides a support for the hybrid formation model.展开更多
The total reaction cross section(1724±93 mb)of 17B at the energy of 43.7 A MeV on C target has been measured by using the transmission method at the Radioactive Ion Beam Line in Lanzhou(RIBLL).Assuming 17B consis...The total reaction cross section(1724±93 mb)of 17B at the energy of 43.7 A MeV on C target has been measured by using the transmission method at the Radioactive Ion Beam Line in Lanzhou(RIBLL).Assuming 17B consists of a core 15B plus two halo neutrons,the total cross section of 17B on C target was calculated with the zero-range Glauber model,where double Gaussian density distributions and Gaussian plus HO density distributions were used.It can fit the experimental data very well.The characteristic of halo structure for 17B was found with a large diffusion of the neutrons density distribution.展开更多
We have accurately evaluated the halo pairwise velocity dispersion and the halo mean streaming velocity in the LCDM model (the fiat ω0 = 0.3 model) using a set of high-resolution N-body simulations. Based on the simu...We have accurately evaluated the halo pairwise velocity dispersion and the halo mean streaming velocity in the LCDM model (the fiat ω0 = 0.3 model) using a set of high-resolution N-body simulations. Based on the simulation results, we have developed a model for the pairwise velocity dispersion of halos. Our model agrees with the simulation results over all scales we studied. We have also tested the model of Sheth et al. for the mean streaming motion of halos derived from the pair-conservation equation. We found that their model reproduces the simulation data very well on large scale, but under-predicts the streaming motion on scales r < 10 h-1 Mpc. We have introduced an empirical relation to improve their model. These improved models are useful for predicting the redshift correlation functions and the redshift power spectrum of galaxies if the halo occupation number model, e.g. the cluster weighted model, is given for the galaxies.展开更多
Introduction-Nuclei near and beyond the proton drip line represent a fascinating frontier in the nuclear landscape. Proton-rich nuclei exhibit intriguing phenomena, such as the Thomas-Ehrman shift and proton-halo stru...Introduction-Nuclei near and beyond the proton drip line represent a fascinating frontier in the nuclear landscape. Proton-rich nuclei exhibit intriguing phenomena, such as the Thomas-Ehrman shift and proton-halo structure. Beyond the proton dripline, nuclei become unbound, allowing protons to be emitted and giving rise to novel radioactive decay modes. Single-proton radioactivity, a process in which some nuclei with an odd number of protons(Z) decay by ejecting a proton, was discovered several decades ago and has been extensively studied [1, 2].展开更多
Using the axially deformed relativistic Hartree-Fock-Bogoliubov(D-RHFB)model,we explore the mechanism behind the parity inversion and halo occurrence in^(11)Be,which are well reproduced by the RHF Lagrangian PKA1.It i...Using the axially deformed relativistic Hartree-Fock-Bogoliubov(D-RHFB)model,we explore the mechanism behind the parity inversion and halo occurrence in^(11)Be,which are well reproduced by the RHF Lagrangian PKA1.It is illustrated that evidently enhanced deformation effects by theπ-pseudo-vector andρ-tensor couplings in PKA1 are crucial for correctly describing both the even-parity ground state(GS)and the neutron halo of^(11)Be.Coupling with the deformation,the intrude 1d_(5/2)component largely enhances the couplings between the evenparity orbit 1/2_(2)^(+)and the nuclear core to ensure an even-parity GS,whereas the 2s_(1/2)component therein dominates the halo formation in^(11)Be.Moreover,the deformed halo in^(11)Be is found to be stabilized by the attractive inherent correlations between the 1d_(5/2)and 2s_(1/2)components of the halo orbit 1/2_(2)^(+),instead of pairing correlations,which paves a new way for understanding the halo pictures in deformed unstable nuclei.展开更多
基金Supported by National Natural Science Foundation of China under Grant Nos.10975116 and 11275160
文摘The structure of Ne isotopes has been investigated by using deformed Skyrme-Hartree-Fock （SHF） method and BCS approximation. Especially the effect of tensor force on the halo structure of 29Ne and 31Ne is discussed. To this end, the tensor contributions are considered to the energy density function and the single particle potential in SHF theory. For comparison, four Skyrme interactions are used： SLy5 and SGII without tensor force, and SLy5＋T and SGII＋ T with tensor force. The results indicate that the inclusion of tensor force shows a more pronounced halo structure for 31Ne.
基金Supported by National Natural Science Foundation of China (11075133,10205019,11075190)Fundamental Research Funds for the Central Universities (XDJK2010D005,XDJK2010C049)+1 种基金Knowledge Innovation Program of Chinese Academy of Sciences(KJCX2-YW-N44)Open Research Program at Large Scale Facility of Chinese Academy of Sciences (O903010YKF)
文摘The properties of neutron-rich boron isotopes are studied in the relativistic continuum Hartree-Bogoliubov theory in coordinate space with NL-SH,PK1 and TM2 effective interactions.Pairing corrections are taken into account by a density dependent force of zero range.The binding energies calculated for these nuclei agree with the experimental data quite well.The neutron-rich nucleus 17 B has been predicted to have a two-neutron halo structure in its ground state.The halo structure of 17 B is reproduced in a self-consistent way,and this halo is shown to be formed by the valence neutron level 2s 1/2.
基金the National Natural Science Foundation of China
文摘We used the star counts in 21 BATC fields obtained with the National Astronomical Observatories （NAOC） 60/90 cm Schmidt Telescope to study the structure of the Galactic halo. Adopting a de Vaucouleurs r1/4 law halo, we found that the halo is somewhat flatter （c/a - 0.4） towards the Galactic center than in the anticentre and antirotation direction （c/a 〉 0.4）. We also notice that the axial ratios are smaller （flatter） towards the low latitude fields than the high latitude fields, except for a few fields. We provide robust limits on the large-scale flattening of the halo. Our analysis shows that the axial ratio of the halo may vary with distance and the observation direction. At large Galactocentric radii, the halo may not have a smooth density distribution, but rather, it may be largely composed of overlapping streams or substructures, which provides a support for the hybrid formation model.
基金the National Natural Science Foundation of China(Grant Nos.10475098,10605033 and 10221003)the Chinese Academy of Sciences(Grant Nos.CXTD-J2005-1 and KJCX2-SW-N18)Hundred Talent Project of CAS(Grant No.0501080BR0)
文摘The total reaction cross section(1724±93 mb)of 17B at the energy of 43.7 A MeV on C target has been measured by using the transmission method at the Radioactive Ion Beam Line in Lanzhou(RIBLL).Assuming 17B consists of a core 15B plus two halo neutrons,the total cross section of 17B on C target was calculated with the zero-range Glauber model,where double Gaussian density distributions and Gaussian plus HO density distributions were used.It can fit the experimental data very well.The characteristic of halo structure for 17B was found with a large diffusion of the neutrons density distribution.
基金the National Natural Science Foundation of China.
文摘We have accurately evaluated the halo pairwise velocity dispersion and the halo mean streaming velocity in the LCDM model (the fiat ω0 = 0.3 model) using a set of high-resolution N-body simulations. Based on the simulation results, we have developed a model for the pairwise velocity dispersion of halos. Our model agrees with the simulation results over all scales we studied. We have also tested the model of Sheth et al. for the mean streaming motion of halos derived from the pair-conservation equation. We found that their model reproduces the simulation data very well on large scale, but under-predicts the streaming motion on scales r < 10 h-1 Mpc. We have introduced an empirical relation to improve their model. These improved models are useful for predicting the redshift correlation functions and the redshift power spectrum of galaxies if the halo occupation number model, e.g. the cluster weighted model, is given for the galaxies.
文摘Introduction-Nuclei near and beyond the proton drip line represent a fascinating frontier in the nuclear landscape. Proton-rich nuclei exhibit intriguing phenomena, such as the Thomas-Ehrman shift and proton-halo structure. Beyond the proton dripline, nuclei become unbound, allowing protons to be emitted and giving rise to novel radioactive decay modes. Single-proton radioactivity, a process in which some nuclei with an odd number of protons(Z) decay by ejecting a proton, was discovered several decades ago and has been extensively studied [1, 2].
基金partly supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDB34000000)the National Natural Science Foundation of China(12275111)the Fundamental Research Funds for the Central Universities(lzujbky-2021–sp41,lzujbky-2021–sp36)。
文摘Using the axially deformed relativistic Hartree-Fock-Bogoliubov(D-RHFB)model,we explore the mechanism behind the parity inversion and halo occurrence in^(11)Be,which are well reproduced by the RHF Lagrangian PKA1.It is illustrated that evidently enhanced deformation effects by theπ-pseudo-vector andρ-tensor couplings in PKA1 are crucial for correctly describing both the even-parity ground state(GS)and the neutron halo of^(11)Be.Coupling with the deformation,the intrude 1d_(5/2)component largely enhances the couplings between the evenparity orbit 1/2_(2)^(+)and the nuclear core to ensure an even-parity GS,whereas the 2s_(1/2)component therein dominates the halo formation in^(11)Be.Moreover,the deformed halo in^(11)Be is found to be stabilized by the attractive inherent correlations between the 1d_(5/2)and 2s_(1/2)components of the halo orbit 1/2_(2)^(+),instead of pairing correlations,which paves a new way for understanding the halo pictures in deformed unstable nuclei.
