The observed low-lying K=5/2^(±) positive-and negative-parity bands in the stable nucleus ^(153)Eu are investigated using the reflection-asymmetric triaxial particle rotor model.The experimental energy spectra,en...The observed low-lying K=5/2^(±) positive-and negative-parity bands in the stable nucleus ^(153)Eu are investigated using the reflection-asymmetric triaxial particle rotor model.The experimental energy spectra,energy staggering parameters,and intraband E2 and M1 transition probabilities are well reproduced.The calculated interband B(E1)values are found to depend sensitively on the octupole deformation parameter β_(30),although the energy spectra and intraband E2 and M1 transitions can be reproduced without the octupole degree of freedom.The observed enhanced E1 transition probabilities can be reproduced with β_(30)=0.05.The detailed analysis of the intrinsic wave functions shows these nearly degenerate positive-and negative-parity bands are built on two individual proton configurations,i.e.,dominated by πg_(7/2)[Ω=5/2]and πh_(11/2)[Ω=5/2],respectively,which differs from the parity doublet bands built on a single parity-mixed configuration.展开更多
including octupole correlations in the Nilsson potential,the ground-state rotational bands in the reflection-asymmetric(RA)nuclei are investigated by using the cranked shell model(CSM)with the monopole and quadrupole ...including octupole correlations in the Nilsson potential,the ground-state rotational bands in the reflection-asymmetric(RA)nuclei are investigated by using the cranked shell model(CSM)with the monopole and quadrupole pairing correlations treated by a particle-number-conserving(PNC)method.The experimental kinematic moments ofinertia(Mols)for alternating-parity bands in the even-even nuclei ^(236,238)U and ^(238,240)Pu,as well as paritydoublet bands in the odd-A nuclei 237U and 239Pu are reproduced well by the PNC-CSM calculations.The higher J(1)for the intrinsic s=-i bands in ^(237)U and ^(239)Pu,compared with the s=+1 bands in the neighboring even-even nuclei ^(236,238)U and ^(238,240)Pu,can be attributed to the pairing gap reduction due to the Pauli blocking effect.The gradual increase of J(i)versus rotational frequency can be explained by the pairing gap reduction due to the rotation.The Mols of reflection-asymmetric nuclei are higher than those of reflection-symmetric(RS)nuclei at low rotational frequency.Moreover,the inclusion of a larger octupole deformation 8,in the RA nuclei results in more significant pairing gap reduction compared with the RS nuclei.展开更多
We report a comprehensive study on low-lying parity doublet states of ^(224)Rn by mixing both quadrupole-and octupoleshaped configurations in multireference covariant density functional theory,in which broken symmetri...We report a comprehensive study on low-lying parity doublet states of ^(224)Rn by mixing both quadrupole-and octupoleshaped configurations in multireference covariant density functional theory,in which broken symmetries in configurations are restored using projection techniques.The low-lying energy spectrum is reasonably reproduced when the shape fluctuations in both the quadrupole and octupole shapes are considered.Electric octupole transition strength in ^(224)Rn is found to be B(E3;3_(1)^(-)→0_(1)^(+))=43 W.u.,comparable to that in ^(224)Ra,whose data are 42(3)W.u..Our results indicate that ^(224)Rn shares similar low-energy structure with ^(224)Ra despite the excitation energy of first 3^(−)state of the former nucleus is higher than that of the latter.This study suggests ^(224)Rn is a candidate for the search for permanent electric dipole moment.展开更多
Recent progress regarding multiple chiral doublet bands(MχD)is reviewed from the experimental and theoretical perspectives.In particular,the experimental findings,theoretical predictions,selection rule for electromag...Recent progress regarding multiple chiral doublet bands(MχD)is reviewed from the experimental and theoretical perspectives.In particular,the experimental findings,theoretical predictions,selection rule for electromagnetic transitions,MχD with octupole correlations,and some related topics are highlighted.Based on these discussions,it is of great scientific interest to search for the other MχD,as well as possible chiral wobblers,chirality-parity quartet bands,and chirality-pseudospin triplet(or quartet)bands in the nuclear system.展开更多
The neutron deficient Xe nuclei with A≈120 are predicted to have strong octupole correlation at low spins.In the present study,an attempt was made to improve upon the level scheme and also to examine the signatures o...The neutron deficient Xe nuclei with A≈120 are predicted to have strong octupole correlation at low spins.In the present study,an attempt was made to improve upon the level scheme and also to examine the signatures of octupole correlation in^(118)xe via high spin γ-ray spectroscopy.High spin states in^(118)Xe have been populated via the^(93)Nb(^(28)Si,p2n)^(118)Xe fusion-evaporation reaction at a beam energy of 115 MeV provided by the 15 UD pelletron accelerator facility at IUAC,New Delhi.In the experiment,seven newγ-transitions have been found and placed appropriately in the level scheme.A theoretical study using the triaxial projected shell model(TPSM)approach suggests that the first bandcrossing is due to the alignment of two neutrons,and a parallel band tracking the yrast configuration is the γ-band built on the two-quasiparticle state.Enhanced E1 transition rates measured between opposite parity bands involving vh_(11/2)and vd_(5/2)orbitals having△j=△l=3 indicate the presence of octupole correlation in this nucleus.展开更多
基金Supported partly by the National Key R&D Program of China(2024YFE0109803)the National Natural Science Foundation of China(12205097,11935003,12141501)+2 种基金the Fundamental Research Funds for the Central Universities(2024MS071)the State Key Laboratory of Nuclear Physics and Technology,Peking University(NPT2023ZX03)the High Performance Computing Platform of Peking University。
文摘The observed low-lying K=5/2^(±) positive-and negative-parity bands in the stable nucleus ^(153)Eu are investigated using the reflection-asymmetric triaxial particle rotor model.The experimental energy spectra,energy staggering parameters,and intraband E2 and M1 transition probabilities are well reproduced.The calculated interband B(E1)values are found to depend sensitively on the octupole deformation parameter β_(30),although the energy spectra and intraband E2 and M1 transitions can be reproduced without the octupole degree of freedom.The observed enhanced E1 transition probabilities can be reproduced with β_(30)=0.05.The detailed analysis of the intrinsic wave functions shows these nearly degenerate positive-and negative-parity bands are built on two individual proton configurations,i.e.,dominated by πg_(7/2)[Ω=5/2]and πh_(11/2)[Ω=5/2],respectively,which differs from the parity doublet bands built on a single parity-mixed configuration.
文摘including octupole correlations in the Nilsson potential,the ground-state rotational bands in the reflection-asymmetric(RA)nuclei are investigated by using the cranked shell model(CSM)with the monopole and quadrupole pairing correlations treated by a particle-number-conserving(PNC)method.The experimental kinematic moments ofinertia(Mols)for alternating-parity bands in the even-even nuclei ^(236,238)U and ^(238,240)Pu,as well as paritydoublet bands in the odd-A nuclei 237U and 239Pu are reproduced well by the PNC-CSM calculations.The higher J(1)for the intrinsic s=-i bands in ^(237)U and ^(239)Pu,compared with the s=+1 bands in the neighboring even-even nuclei ^(236,238)U and ^(238,240)Pu,can be attributed to the pairing gap reduction due to the Pauli blocking effect.The gradual increase of J(i)versus rotational frequency can be explained by the pairing gap reduction due to the rotation.The Mols of reflection-asymmetric nuclei are higher than those of reflection-symmetric(RS)nuclei at low rotational frequency.Moreover,the inclusion of a larger octupole deformation 8,in the RA nuclei results in more significant pairing gap reduction compared with the RS nuclei.
基金supported by the National Natural Science Foundation of China (Nos. 12465020, 12005802, and 12005109)the Jiangxi Provincial Natural Science Foundation (20202BAB211008)+3 种基金the Jiangxi Normal University (JXNU) Initial Research Foundation Grant to Doctor (12019504)the Young Talents Program under JXNU (12019870)the PhD Foundation of Chongqing Normal University (No. 23XLB010)the Science and Technology Research Program of Chongqing Municipal Education Commission (No. KJQN202300509)
文摘We report a comprehensive study on low-lying parity doublet states of ^(224)Rn by mixing both quadrupole-and octupoleshaped configurations in multireference covariant density functional theory,in which broken symmetries in configurations are restored using projection techniques.The low-lying energy spectrum is reasonably reproduced when the shape fluctuations in both the quadrupole and octupole shapes are considered.Electric octupole transition strength in ^(224)Rn is found to be B(E3;3_(1)^(-)→0_(1)^(+))=43 W.u.,comparable to that in ^(224)Ra,whose data are 42(3)W.u..Our results indicate that ^(224)Rn shares similar low-energy structure with ^(224)Ra despite the excitation energy of first 3^(−)state of the former nucleus is higher than that of the latter.This study suggests ^(224)Rn is a candidate for the search for permanent electric dipole moment.
基金Supported by the Shandong Natural Science Foundation,China(JQ201701)the National Natural Science Foundation of China(11622540)。
文摘Recent progress regarding multiple chiral doublet bands(MχD)is reviewed from the experimental and theoretical perspectives.In particular,the experimental findings,theoretical predictions,selection rule for electromagnetic transitions,MχD with octupole correlations,and some related topics are highlighted.Based on these discussions,it is of great scientific interest to search for the other MχD,as well as possible chiral wobblers,chirality-parity quartet bands,and chirality-pseudospin triplet(or quartet)bands in the nuclear system.
基金the contribution of the INGA collaboration,which is partially funded by the Department of Science and Technology(DST,GoIproject no.IR/S2/PF-03/2003-I)+4 种基金University Grants Commission(UGC)supported by IUAC,New Delhi(Grant No.IUAC/XIII/7/UFR-63302)financial support from the University Grants Commission(UGC),Indiathe Department of Science and Technology,Govt.of India for providing financial support under Project no.CRG/2019/004960 to carry out a part of the research workthe financial support received from SERB,INDIA under N-PDF scheme vide reference no.PDF/2022/001829
文摘The neutron deficient Xe nuclei with A≈120 are predicted to have strong octupole correlation at low spins.In the present study,an attempt was made to improve upon the level scheme and also to examine the signatures of octupole correlation in^(118)xe via high spin γ-ray spectroscopy.High spin states in^(118)Xe have been populated via the^(93)Nb(^(28)Si,p2n)^(118)Xe fusion-evaporation reaction at a beam energy of 115 MeV provided by the 15 UD pelletron accelerator facility at IUAC,New Delhi.In the experiment,seven newγ-transitions have been found and placed appropriately in the level scheme.A theoretical study using the triaxial projected shell model(TPSM)approach suggests that the first bandcrossing is due to the alignment of two neutrons,and a parallel band tracking the yrast configuration is the γ-band built on the two-quasiparticle state.Enhanced E1 transition rates measured between opposite parity bands involving vh_(11/2)and vd_(5/2)orbitals having△j=△l=3 indicate the presence of octupole correlation in this nucleus.
