High Spin states of the odd-odd <sup>162</sup>Lu nucleus have been studied via <sup>147</sup>Sm(<sup>19</sup>F,4nγ)reaction at90 MeV beam energy.Level scheme for yrast band based ...High Spin states of the odd-odd <sup>162</sup>Lu nucleus have been studied via <sup>147</sup>Sm(<sup>19</sup>F,4nγ)reaction at90 MeV beam energy.Level scheme for yrast band based on π[h<sub>11/2</sub>]v[i<sub>13/2</sub>]configuration was estab-lished,for the first time,up to I<sup>π</sup>=23<sup>-</sup>.This band shows the signature inversion in energy before band-bending generally appeared in this mass region.It is stressed that the signature splitting in <sup>162</sup>Lu is biggerthan that in <sup>160</sup>Tm which could be understood in the framewrok of the cranked shell model if taking posi-tire γ-triaxiality into account.展开更多
基于联合实施微观相互作用玻色子模型的最大F旋方案(sdIBM-Fˉmax)与γ射线能量-自旋曲线(γ-ray energy overspin curves,E-GOS)方案,成功描述了182Os核yrast带相继的SU(3)—U(5)—SU(3)结构相变,由于缺少直观解释而显得抽象.本文借助...基于联合实施微观相互作用玻色子模型的最大F旋方案(sdIBM-Fˉmax)与γ射线能量-自旋曲线(γ-ray energy overspin curves,E-GOS)方案,成功描述了182Os核yrast带相继的SU(3)—U(5)—SU(3)结构相变,由于缺少直观解释而显得抽象.本文借助微观sdIBM-ˉFmax的微观参数与Bohr哈密顿量的势能曲面方程之间存在的泛函关系,几何地给出了对这种相继相变途径的另外一种可能理解;并阐述了在完全变形核的高角动量态中,由于量子效应在高激发态与低激发态之间生成高简并的临界区,提供了γ振动能量会变得低于转动能量的一个可能途径,从而实现了SU(3)—U(5)的相变.展开更多
It is well-known that the sharpness of the first backbending in nuclear yrast spectra depends on the magnitude of the interaction strength between the yrast band and the yrare band, which has a large spin-alignment. B...It is well-known that the sharpness of the first backbending in nuclear yrast spectra depends on the magnitude of the interaction strength between the yrast band and the yrare band, which has a large spin-alignment. Bengtsson, Hamamoto and Mottelson pointed out that in the HFB calculation for a single-j cranking shell model (CSM) the yrast-yrare interaction strength is a periodic function of the Fermi energy, λ, and thus a sharp backbending might be expected not only at the展开更多
In this study,we investigate the robustness of pair structures for nuclear yrast states,that is,whether the structures of relevant collective pairs as building blocks of different yrast states are the same.We focus on...In this study,we investigate the robustness of pair structures for nuclear yrast states,that is,whether the structures of relevant collective pairs as building blocks of different yrast states are the same.We focus on deformed and transitional nuclei and study the yrast states of^(28)Si,^(50)Cr,and^(132)Xe,whose experimental R_(4/2)values are 2.60,2.40,and 2.16,respectively,using the nucleon-pair approximation(NPA)and shell-model effective interactions.For each yrast state,we consider optimized pair structures to be those providing the energy minimum for this state.To find the minimum,many full NPA calculations are performed with varying pair structures,and the numerical optimization procedure of the conjugate gradient method is implemented.Our results suggest that optimized pair structures remain the same for all states within a rotational band of a deformed nucleus.Our results also suggest that after backbending,that is,changing of the intrinsic state,the structure of the S pair,which is essential to build the monopole pairing correlation,remains approximately unchanged,whereas the structures of the non-S pairs,which are essential to build the quadrupole correlation,change significantly.展开更多
The projected shell model is applied to the odd-proton nucleus 83 Rb. The results of theoretical calculationsabout the excited positive-parity yrast states and the negative-parity ground-state band are compared with e...The projected shell model is applied to the odd-proton nucleus 83 Rb. The results of theoretical calculationsabout the excited positive-parity yrast states and the negative-parity ground-state band are compared with experimentaldata, and the best reproduction of the experiment has been given by this model. In addition, a band diagram calculatedfor the negative-parity g.s. band is also shown in order to extract physics out of the numerical results.展开更多
The properties of the high spin states of the neutron-rich 98-102Sr and 100-104Zr isotopes have been st udied using the projected shell model. In particular, the upbending phenomenon is investigated for these isotopes...The properties of the high spin states of the neutron-rich 98-102Sr and 100-104Zr isotopes have been st udied using the projected shell model. In particular, the upbending phenomenon is investigated for these isotopes along the yrast line. The results show that the occurrence of upbending phenomenon is attributed to the band crossing between ground state band and 2-qp neutron band having configuration 2vh11/2[-3/2, 5/2], K = 1. Furthermore, the neutron two-quasi-particle structure of side bands in 98SR-102Zr is discussed in this paper.展开更多
In the N=88,90 region,a strong negative drive of γ deformation is generatedby the second lowest positive signature vi<sub>13/2</sub> quasiparticle orbital.In contrast,thelowest positive-parity and negativ...In the N=88,90 region,a strong negative drive of γ deformation is generatedby the second lowest positive signature vi<sub>13/2</sub> quasiparticle orbital.In contrast,thelowest positive-parity and negative-parity orbitals in this region exhibit positive drivesin the γ deformation toward oblate shapes.Replacing one of these with the negativedrive orbital strengthens the collectivity for the side band configurations at very highspins.展开更多
In the present work the nuclear structure properties and the backbending phenomena of even-even isotopes at A ≈ 70 mass region are analyzed using two simultaneous theoretical models based on a simple modified version...In the present work the nuclear structure properties and the backbending phenomena of even-even isotopes at A ≈ 70 mass region are analyzed using two simultaneous theoretical models based on a simple modified version of the collective model predictions besides an improved version of exponential model with the inclusion of pairing correlation. In general, both models successfully describe the backbending phenomena in that region. From the comparison between the predictions of the two proposed models a firm conclusion is obtained concerning the superiority of the simple improved version of the exponential model in describing the forward and down-bending region of the φ-ω<sup>2</sup> plots.展开更多
基金①The project supported partly by the National Education Commission Foundationthe National Natural Science Foundation of China
文摘High Spin states of the odd-odd <sup>162</sup>Lu nucleus have been studied via <sup>147</sup>Sm(<sup>19</sup>F,4nγ)reaction at90 MeV beam energy.Level scheme for yrast band based on π[h<sub>11/2</sub>]v[i<sub>13/2</sub>]configuration was estab-lished,for the first time,up to I<sup>π</sup>=23<sup>-</sup>.This band shows the signature inversion in energy before band-bending generally appeared in this mass region.It is stressed that the signature splitting in <sup>162</sup>Lu is biggerthan that in <sup>160</sup>Tm which could be understood in the framewrok of the cranked shell model if taking posi-tire γ-triaxiality into account.
文摘基于联合实施微观相互作用玻色子模型的最大F旋方案(sdIBM-Fˉmax)与γ射线能量-自旋曲线(γ-ray energy overspin curves,E-GOS)方案,成功描述了182Os核yrast带相继的SU(3)—U(5)—SU(3)结构相变,由于缺少直观解释而显得抽象.本文借助微观sdIBM-ˉFmax的微观参数与Bohr哈密顿量的势能曲面方程之间存在的泛函关系,几何地给出了对这种相继相变途径的另外一种可能理解;并阐述了在完全变形核的高角动量态中,由于量子效应在高激发态与低激发态之间生成高简并的临界区,提供了γ振动能量会变得低于转动能量的一个可能途径,从而实现了SU(3)—U(5)的相变.
文摘It is well-known that the sharpness of the first backbending in nuclear yrast spectra depends on the magnitude of the interaction strength between the yrast band and the yrare band, which has a large spin-alignment. Bengtsson, Hamamoto and Mottelson pointed out that in the HFB calculation for a single-j cranking shell model (CSM) the yrast-yrare interaction strength is a periodic function of the Fermi energy, λ, and thus a sharp backbending might be expected not only at the
基金Supported by the National Natural Science Foundation of China(11875134,11875188,12175071,11975151,11961141003)the Shanghai Key Laboratory of Particle Physics and Cosmology(21DZ2271500-2)。
文摘In this study,we investigate the robustness of pair structures for nuclear yrast states,that is,whether the structures of relevant collective pairs as building blocks of different yrast states are the same.We focus on deformed and transitional nuclei and study the yrast states of^(28)Si,^(50)Cr,and^(132)Xe,whose experimental R_(4/2)values are 2.60,2.40,and 2.16,respectively,using the nucleon-pair approximation(NPA)and shell-model effective interactions.For each yrast state,we consider optimized pair structures to be those providing the energy minimum for this state.To find the minimum,many full NPA calculations are performed with varying pair structures,and the numerical optimization procedure of the conjugate gradient method is implemented.Our results suggest that optimized pair structures remain the same for all states within a rotational band of a deformed nucleus.Our results also suggest that after backbending,that is,changing of the intrinsic state,the structure of the S pair,which is essential to build the monopole pairing correlation,remains approximately unchanged,whereas the structures of the non-S pairs,which are essential to build the quadrupole correlation,change significantly.
文摘The projected shell model is applied to the odd-proton nucleus 83 Rb. The results of theoretical calculationsabout the excited positive-parity yrast states and the negative-parity ground-state band are compared with experimentaldata, and the best reproduction of the experiment has been given by this model. In addition, a band diagram calculatedfor the negative-parity g.s. band is also shown in order to extract physics out of the numerical results.
基金Supported by the Natural Science Foundation of China under Grant Nos. 10975051, 10979024, 10905021the Natural Science Foundation of Zhejiang province, China under Grant No. Y6090210the Natural Science Foundation of Huzhou under Grant No. 2010YZll
文摘The properties of the high spin states of the neutron-rich 98-102Sr and 100-104Zr isotopes have been st udied using the projected shell model. In particular, the upbending phenomenon is investigated for these isotopes along the yrast line. The results show that the occurrence of upbending phenomenon is attributed to the band crossing between ground state band and 2-qp neutron band having configuration 2vh11/2[-3/2, 5/2], K = 1. Furthermore, the neutron two-quasi-particle structure of side bands in 98SR-102Zr is discussed in this paper.
基金The projecet supported by National Natural Science Foundation of ChinaResearch at the University of Tennessee is supported by the Department of Energy through Contract Number DE-AS05-76ERO-4936.
文摘In the N=88,90 region,a strong negative drive of γ deformation is generatedby the second lowest positive signature vi<sub>13/2</sub> quasiparticle orbital.In contrast,thelowest positive-parity and negative-parity orbitals in this region exhibit positive drivesin the γ deformation toward oblate shapes.Replacing one of these with the negativedrive orbital strengthens the collectivity for the side band configurations at very highspins.
文摘In the present work the nuclear structure properties and the backbending phenomena of even-even isotopes at A ≈ 70 mass region are analyzed using two simultaneous theoretical models based on a simple modified version of the collective model predictions besides an improved version of exponential model with the inclusion of pairing correlation. In general, both models successfully describe the backbending phenomena in that region. From the comparison between the predictions of the two proposed models a firm conclusion is obtained concerning the superiority of the simple improved version of the exponential model in describing the forward and down-bending region of the φ-ω<sup>2</sup> plots.
