Based on the relativistic calculations of the nuclear masses in the transfermium region from No(Z=102)to Ds(Z=110)using the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc),the possible existence of...Based on the relativistic calculations of the nuclear masses in the transfermium region from No(Z=102)to Ds(Z=110)using the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc),the possible existence of bound nuclei beyond the neutron drip lines is studied.The two-neutron and multi-neutron emission bound nuclei beyond the primary neutron drip line of N=258 are predicted in Z=106,108,and 110 isotopes.A detailed microscopic mechanism investigation reveals that nuclear deformation plays a vital role in the existence of bound nuclei beyond the drip line.Furthermore,not only the quadrupole deformation β_(2) but also the higher orders of deformation are indispensable in the reliable description of the phenomenon of reentrant binding.展开更多
Unknown β delayed proton precursor 121 Ce was produced via the reaction of 92 Mo( 32 S, 3n), and identified by an He jet fast tape transport system with "P γ" coincidence measurements. The half life of 121...Unknown β delayed proton precursor 121 Ce was produced via the reaction of 92 Mo( 32 S, 3n), and identified by an He jet fast tape transport system with "P γ" coincidence measurements. The half life of 121 Ce decay was determined to be (1.1±0.1)s. Its energy spectrum of β delayed protons was measured and the β delayed proton branching ratio for 121 Ce decay was roughly estimated to be ～1%. After β delayed proton decay of the precursors \{ 119 Ba,\} \{ 121 Ba\} and 122 La, some of γ transitions from low lying states to the ground states in their "daughters" were observed for the first time.展开更多
A new method is proposed to determine the binding energy(B)of near proton-drip line isotopes from isotopic cross section distribution.To determine B of Z=22-28 isotopes(with T_z=-2 and-5/2),the lack of cross sections ...A new method is proposed to determine the binding energy(B)of near proton-drip line isotopes from isotopic cross section distribution.To determine B of Z=22-28 isotopes(with T_z=-2 and-5/2),the lack of cross sections for proton-rich isotopes in the 345A MeV^(78)Kr+~9Be is overcome by predicting the proton-rich isotopes from a newly discovered scaling phenomenon found in the proton-rich isotopes measured in the 140A MeV^(40,48)Ca(^(58,64)Ni)+~9Be reactions.The cross sections for proton-rich isotopes are verified to exponentially depend on the average binding energy per nucleon,based on which B of the Z=22-28 isotopes with T_z=-2 and-5/2 are determined from cross sections.The determined B of the isotopes are justified from obeying the scaling phenomenon of the difference between the mass of mirror nuclei.The cross sections for the Z=22-28 isotopes with T_z=-1 and-3/2,which in potential can be experimentally studied in mass storage ring,are also predicted.展开更多
The β-delayed proton precursors125Nd128Pm129Sm,137Gd and139Dy near the proton drip line were produced by the irradiation of92Mo,96Ru and106Cd with an36Ar beam, and conclusively identified for the first time by using ...The β-delayed proton precursors125Nd128Pm129Sm,137Gd and139Dy near the proton drip line were produced by the irradiation of92Mo,96Ru and106Cd with an36Ar beam, and conclusively identified for the first time by using proton-gamma coincidence in combination with a He-jet tape transport system. Their half-lives were determined to be 0.60(15)s,1.0(3)s,O.55(10)s,2.2(2)s and 0.6 (2)s, respectively. The measured energy spectra of β-delayed protons and estimated proton branching ratios to the final states in “daughter” nuclei for the precursors125Nd,129Sm,137Gd and139Dy, as well as the previously reported ones for the precursors135Gd and121Ce, were fitted by a statistical model calculation. The ground-state spins and parities of121Ce,125Nd,129Sm,139Gd,137Gd and139Dy were then assigned as 5/2±,5/2±, 1/2± (or 3/2+), 5/2+,7/2+- and 7/2, respectively. The consistency between the experimental spin-parity assignment and the predicted Nilsson diagrams indirectly indicates that the ground states of121Ce,125Nd,129Sm,135Gd,137Gd and139Dy are highly deformed with β2, - 0.3.展开更多
The effects of an additional K-meson on the ground-state properties of nuclei are investigated within an axially-deformed Skyrme-Hartree-Fock approach combined with a Skyrme-type kaon-nucleon interaction.The K-meson i...The effects of an additional K-meson on the ground-state properties of nuclei are investigated within an axially-deformed Skyrme-Hartree-Fock approach combined with a Skyrme-type kaon-nucleon interaction.The K-meson increases the binding energies of all nuclei,whereas it affects deformations only for light nuclei without shell closure.The nucleon drip lines are modified due to the strongly attractive K-N interaction.This is attributed to the behavior of the highest-occupied nucleon single-particle levels near the drip lines,which is analyzed in detail.展开更多
Starting from the CD-Bonn potential, we have performed Gamow shell-model calculations for neutronrich oxygen isotopes, investigating excitation spectra and their resonant properties. The Gamow shell model is based on ...Starting from the CD-Bonn potential, we have performed Gamow shell-model calculations for neutronrich oxygen isotopes, investigating excitation spectra and their resonant properties. The Gamow shell model is based on the Berggren ensemble, which is capable of treating the continuum effect reasonably in weakly bound or unbound nuclei. To calculate heavier-mass oxygen isotopes, we choose ^16O as a frozen core in the Camow shell-model calculations. The first 2^＋ excitation energies of the even-even O isotopes are calculated, and compared with those obtained by the conventional shell model using the empirical USDB interaction. The continuum effect is proved to play an important role in the shell evolution near the drip line. We also discuss the effect of the Berggren contour choice. We improve the approximation in the contour choice to give more precise calculations of resonance widths.展开更多
基金Supported by the National Natural Science Foundation of China(U2032138,11775112,12075085,11935003,12047568,11790323,11790325)the State Key Laboratory of Nuclear Physics and Technology,Peking University(NPT2020ZZ01)。
文摘Based on the relativistic calculations of the nuclear masses in the transfermium region from No(Z=102)to Ds(Z=110)using the deformed relativistic Hartree-Bogoliubov theory in continuum(DRHBc),the possible existence of bound nuclei beyond the neutron drip lines is studied.The two-neutron and multi-neutron emission bound nuclei beyond the primary neutron drip line of N=258 are predicted in Z=106,108,and 110 isotopes.A detailed microscopic mechanism investigation reveals that nuclear deformation plays a vital role in the existence of bound nuclei beyond the drip line.Furthermore,not only the quadrupole deformation β_(2) but also the higher orders of deformation are indispensable in the reliable description of the phenomenon of reentrant binding.
文摘Unknown β delayed proton precursor 121 Ce was produced via the reaction of 92 Mo( 32 S, 3n), and identified by an He jet fast tape transport system with "P γ" coincidence measurements. The half life of 121 Ce decay was determined to be (1.1±0.1)s. Its energy spectrum of β delayed protons was measured and the β delayed proton branching ratio for 121 Ce decay was roughly estimated to be ～1%. After β delayed proton decay of the precursors \{ 119 Ba,\} \{ 121 Ba\} and 122 La, some of γ transitions from low lying states to the ground states in their "daughters" were observed for the first time.
基金supported by the National Natural Science Foundation of China(Grant Nos.11421505,and U1732135)the Major State Basic Research Development Program in China(Grant No.2014CB845401)+1 种基金the Natural Science Foundation of Henan Province(Grant No.162300410179)the Henan Normal University for the Excellent Youth(Grant No.154100510007)
文摘A new method is proposed to determine the binding energy(B)of near proton-drip line isotopes from isotopic cross section distribution.To determine B of Z=22-28 isotopes(with T_z=-2 and-5/2),the lack of cross sections for proton-rich isotopes in the 345A MeV^(78)Kr+~9Be is overcome by predicting the proton-rich isotopes from a newly discovered scaling phenomenon found in the proton-rich isotopes measured in the 140A MeV^(40,48)Ca(^(58,64)Ni)+~9Be reactions.The cross sections for proton-rich isotopes are verified to exponentially depend on the average binding energy per nucleon,based on which B of the Z=22-28 isotopes with T_z=-2 and-5/2 are determined from cross sections.The determined B of the isotopes are justified from obeying the scaling phenomenon of the difference between the mass of mirror nuclei.The cross sections for the Z=22-28 isotopes with T_z=-1 and-3/2,which in potential can be experimentally studied in mass storage ring,are also predicted.
文摘The β-delayed proton precursors125Nd128Pm129Sm,137Gd and139Dy near the proton drip line were produced by the irradiation of92Mo,96Ru and106Cd with an36Ar beam, and conclusively identified for the first time by using proton-gamma coincidence in combination with a He-jet tape transport system. Their half-lives were determined to be 0.60(15)s,1.0(3)s,O.55(10)s,2.2(2)s and 0.6 (2)s, respectively. The measured energy spectra of β-delayed protons and estimated proton branching ratios to the final states in “daughter” nuclei for the precursors125Nd,129Sm,137Gd and139Dy, as well as the previously reported ones for the precursors135Gd and121Ce, were fitted by a statistical model calculation. The ground-state spins and parities of121Ce,125Nd,129Sm,139Gd,137Gd and139Dy were then assigned as 5/2±,5/2±, 1/2± (or 3/2+), 5/2+,7/2+- and 7/2, respectively. The consistency between the experimental spin-parity assignment and the predicted Nilsson diagrams indirectly indicates that the ground states of121Ce,125Nd,129Sm,135Gd,137Gd and139Dy are highly deformed with β2, - 0.3.
基金Supported by the National Natural Science Foundation of China(12175071,11775081)。
文摘The effects of an additional K-meson on the ground-state properties of nuclei are investigated within an axially-deformed Skyrme-Hartree-Fock approach combined with a Skyrme-type kaon-nucleon interaction.The K-meson increases the binding energies of all nuclei,whereas it affects deformations only for light nuclei without shell closure.The nucleon drip lines are modified due to the strongly attractive K-N interaction.This is attributed to the behavior of the highest-occupied nucleon single-particle levels near the drip lines,which is analyzed in detail.
基金Supported by the National Key R&D Program of China(2018YFA0404401)the National Natural Science Foundation of China(11320101004,11575007)+2 种基金the China Postdoctoral Science Foundation(2018M630018)the CUSTIPEN(China U.S.Theory Institute for Physics with Exotic Nuclei)funded by the U.S.Department of Energy,Office of Science(DESC0009971)and High performance Computing Platform of Peking University
文摘Starting from the CD-Bonn potential, we have performed Gamow shell-model calculations for neutronrich oxygen isotopes, investigating excitation spectra and their resonant properties. The Gamow shell model is based on the Berggren ensemble, which is capable of treating the continuum effect reasonably in weakly bound or unbound nuclei. To calculate heavier-mass oxygen isotopes, we choose ^16O as a frozen core in the Camow shell-model calculations. The first 2^＋ excitation energies of the even-even O isotopes are calculated, and compared with those obtained by the conventional shell model using the empirical USDB interaction. The continuum effect is proved to play an important role in the shell evolution near the drip line. We also discuss the effect of the Berggren contour choice. We improve the approximation in the contour choice to give more precise calculations of resonance widths.
