New Insights into Frontier of Nuclear Structure of Neutronrich Nuclei by Means of Prompt Fission γ Ray Measurements at Gammasphere(II: Section 3 &amp; Section 4)

Y.X.Luo; J.H.Hamilton; J.O.Rasmussen; A.V.Ramayya; C.Goodin; A.V.Daniel; N.J.Stone; S.J.Zhu; J.K.Hwang; S.H.Liu; C.J.Beyer; Ke Li; H.L.Crowell; D.Almehed; S.Frauendorf; A.Covello0; V.Dimitrov; Jing-ye Zhang; X.L.Che; Z.Jang; D.Fong; A.Gelberg; I.Stefanescu; A.Gargano0; E.F.Jones; P.M.Gore; I.Y.Lee; G.M.Ter-Akopian; Yu.Ts.Oganessian; M.A.Stoyer; R.Donangelo; W.C.Ma; J.D.Cole; J.Kormicki; X.Q.Zhang; S.C.Wu; J.Gilat; T.N.Ginter; S.J.Asztalos0

doi:10.11804/NuclPhysRev.27.04.363

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Article Navigation > Nuclear Physics Review > 2010 > 27(4): 363-389

Y.X.Luo, J.H.Hamilton, J.O.Rasmussen, A.V.Ramayya, C.Goodin, A.V.Daniel, N.J.Stone, S.J.Zhu, J.K.Hwang, S.H.Liu, C.J.Beyer, Ke Li, H.L.Crowell, D.Almehed, S.Frauendorf, A.Covello0, V.Dimitrov, Jing-ye Zhang, X.L.Che, Z.Jang, D.Fong, A.Gelberg, I.Stefanescu, A.Gargano0, E.F.Jones, P.M.Gore, I.Y.Lee, G.M.Ter-Akopian, Yu.Ts.Oganessian, M.A.Stoyer, R.Donangelo, W.C.Ma, J.D.Cole, J.Kormicki, X.Q.Zhang, S.C.Wu, J.Gilat, T.N.Ginter, S.J.Asztalos0. New Insights into Frontier of Nuclear Structure of Neutronrich Nuclei by Means of Prompt Fission γ Ray Measurements at Gammasphere(II: Section 3 & Section 4)[J]. Nuclear Physics Review, 2010, 27(4): 363-389. doi: 10.11804/NuclPhysRev.27.04.363

Citation:

Y.X.Luo, J.H.Hamilton, J.O.Rasmussen, A.V.Ramayya, C.Goodin, A.V.Daniel, N.J.Stone, S.J.Zhu, J.K.Hwang, S.H.Liu, C.J.Beyer, Ke Li, H.L.Crowell, D.Almehed, S.Frauendorf, A.Covello0, V.Dimitrov, Jing-ye Zhang, X.L.Che, Z.Jang, D.Fong, A.Gelberg, I.Stefanescu, A.Gargano0, E.F.Jones, P.M.Gore, I.Y.Lee, G.M.Ter-Akopian, Yu.Ts.Oganessian, M.A.Stoyer, R.Donangelo, W.C.Ma, J.D.Cole, J.Kormicki, X.Q.Zhang, S.C.Wu, J.Gilat, T.N.Ginter, S.J.Asztalos0. New Insights into Frontier of Nuclear Structure of Neutronrich Nuclei by Means of Prompt Fission γ Ray Measurements at Gammasphere(II: Section 3 & Section 4)[J]. Nuclear Physics Review, 2010, 27(4): 363-389. doi: 10.11804/NuclPhysRev.27.04.363

New Insights into Frontier of Nuclear Structure of Neutronrich Nuclei by Means of Prompt Fission γ Ray Measurements at Gammasphere(II: Section 3 & Section 4)

doi: 10.11804/NuclPhysRev.27.04.363

(1 Physics Department, Vanderbilt University, Nashville, TN 37235, USA;2 Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA;3 Flerov Laboratory for Nuclear Reactions, JINR, Dubna, Russia;4 Joint Institute for Heavy Ion Research, Oak Ridge, TN 37831, USA;5 Department of Physics, Oxford University, Oxford OX1 3PU, United Kingdom;6 Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA;7 Physics Department, Tsinghua University, Beijing 100084, China;8 Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA;9 Institut für Strahlenphysik, FZDRossendorf, Postfach 510119, D01314 Dresden, Germany;10 Dipartimento di Scienze Fisiche, Universita di Napoli Federico II, and Istituto Nazionale di Fisica Nuclear, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Napoli, Italy;......

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Corresponding author: Y.X.Luo
Received Date: 1900-01-01
Rev Recd Date: 1900-01-01
Publish Date: 2010-12-20

Abstract

By means of γ-γ-γ and γ-γ(θ) measurements of prompt fission γ rays from ²⁵²Cf using Gammasphere, new insights have been gained into the A~100 (Z~40, N>56) neutron rich region, which has long been of interest for shape transitions, shape coexistence and onset of deformations. The systematic investigations of odd-Z isotopes have revealed a shape transition from axially symmetric shapes with very large quadrupole deformations in Z=39 (Y) to near maximum triaxial shapes with moderate quadrupole deformations in Z=43 (Tc), 44 (Ru), 45 (Rh) isotopes. The Nb (Z=41) isotopes are found to be transitional with regard to this shape transition. The bandcrossings observed in the evenN Tc and Rh isotopes are attributed to alignment of a pair of h_11/2neutrons. The longexpected sudden shape transition in Nb isotopic chain is now observed. The longsought highspin level scheme and deformed states in ¹⁰⁰Nb (N=59) were identified. The ground state of ¹⁰⁰Nb was found to be strongly deformed, in disagreement with existing theory. The shape coexistence was confirmed in the nucleus, and the sudden shape transition in the Nb isotopic chain was seen to occur between N=58 (spherical) to N=59 (strongly deformed), in contrast to the sudden shape transition from N=59 (spherical) toN=60 (strongly deformed) in Sr (Z=38), Y (Z=39) and Zr (Z=40) isotopic chains. The observation of strongly deformed ground state in ¹⁰⁰Nb and its very large and irregular moments of inertia make ¹⁰⁰Nb an especially interesting case for further theoretical studies.
Recent detailed studies of octupole excitations in odd-Z Cs (Z=55) and La (Z=57) isotopes have discovered a sharp drop in electric dipole moments D₀ in the Cs isotopic chain ^{141, 143, 144}Cs, and, most likely, the previously reported moderate drop in D₀in ^{145, 147}La is extended sharply down in ¹⁴⁸La. The sharp drops of D₀ in Cs and La are most likely analogous to those reported in ¹⁴⁶Ba and ²²⁴Ra, which were accounted for by the reflectionasymmetric mean field shell correction theory. The very large D₀in both ¹⁴¹Cs and ¹⁴²Xe and the simplexdependent D₀deduced in ¹⁴¹Cs but not in ¹⁴³Cs need further theoretical studies. Based on rotational frequency ratios, ω^-(I)/ω⁺(I), octupole vibrations are proposed in Cs isotopes, like the cases in Xe isotopes, while octupole deformations are suggested in La isotopes.
- shape transition,
- axially symmetric shape,
- triaxial deformation,
- onset of deformation,
- bandcrossing,
- odd-Z,
- octupole excitations,
- B(E1)/B(E2) values,
- electric dipole moment D₀,
- sharp drop of dipole moments,
- octupole vibrations,
- Cs,
- La isotopes
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沈阳化工大学材料科学与工程学院沈阳 110142

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New Insights into Frontier of Nuclear Structure of Neutronrich Nuclei by Means of Prompt Fission γ Ray Measurements at Gammasphere(II: Section 3 & Section 4)

doi: 10.11804/NuclPhysRev.27.04.363

(1 Physics Department, Vanderbilt University, Nashville, TN 37235, USA;2 Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA;3 Flerov Laboratory for Nuclear Reactions, JINR, Dubna, Russia;4 Joint Institute for Heavy Ion Research, Oak Ridge, TN 37831, USA;5 Department of Physics, Oxford University, Oxford OX1 3PU, United Kingdom;6 Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA;7 Physics Department, Tsinghua University, Beijing 100084, China;8 Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA;9 Institut für Strahlenphysik, FZDRossendorf, Postfach 510119, D01314 Dresden, Germany;10 Dipartimento di Scienze Fisiche, Universita di Napoli Federico II, and Istituto Nazionale di Fisica Nuclear, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Napoli, Italy;......

Corresponding author: Y.X.Luo

Received Date: 1900-01-01
Rev Recd Date: 1900-01-01
Publish Date: 2010-12-20

Key words:

Abstract: By means of γ-γ-γ and γ-γ(θ) measurements of prompt fission γ rays from ²⁵²Cf using Gammasphere, new insights have been gained into the A~100 (Z~40, N>56) neutron rich region, which has long been of interest for shape transitions, shape coexistence and onset of deformations. The systematic investigations of odd-Z isotopes have revealed a shape transition from axially symmetric shapes with very large quadrupole deformations in Z=39 (Y) to near maximum triaxial shapes with moderate quadrupole deformations in Z=43 (Tc), 44 (Ru), 45 (Rh) isotopes. The Nb (Z=41) isotopes are found to be transitional with regard to this shape transition. The bandcrossings observed in the evenN Tc and Rh isotopes are attributed to alignment of a pair of h_11/2neutrons. The longexpected sudden shape transition in Nb isotopic chain is now observed. The longsought highspin level scheme and deformed states in ¹⁰⁰Nb (N=59) were identified. The ground state of ¹⁰⁰Nb was found to be strongly deformed, in disagreement with existing theory. The shape coexistence was confirmed in the nucleus, and the sudden shape transition in the Nb isotopic chain was seen to occur between N=58 (spherical) to N=59 (strongly deformed), in contrast to the sudden shape transition from N=59 (spherical) toN=60 (strongly deformed) in Sr (Z=38), Y (Z=39) and Zr (Z=40) isotopic chains. The observation of strongly deformed ground state in ¹⁰⁰Nb and its very large and irregular moments of inertia make ¹⁰⁰Nb an especially interesting case for further theoretical studies.
Recent detailed studies of octupole excitations in odd-Z Cs (Z=55) and La (Z=57) isotopes have discovered a sharp drop in electric dipole moments D₀ in the Cs isotopic chain ^{141, 143, 144}Cs, and, most likely, the previously reported moderate drop in D₀in ^{145, 147}La is extended sharply down in ¹⁴⁸La. The sharp drops of D₀ in Cs and La are most likely analogous to those reported in ¹⁴⁶Ba and ²²⁴Ra, which were accounted for by the reflectionasymmetric mean field shell correction theory. The very large D₀in both ¹⁴¹Cs and ¹⁴²Xe and the simplexdependent D₀deduced in ¹⁴¹Cs but not in ¹⁴³Cs need further theoretical studies. Based on rotational frequency ratios, ω^-(I)/ω⁺(I), octupole vibrations are proposed in Cs isotopes, like the cases in Xe isotopes, while octupole deformations are suggested in La isotopes.

Citation:

Y.X.Luo, J.H.Hamilton, J.O.Rasmussen, A.V.Ramayya, C.Goodin, A.V.Daniel, N.J.Stone, S.J.Zhu, J.K.Hwang, S.H.Liu, C.J.Beyer, Ke Li, H.L.Crowell, D.Almehed, S.Frauendorf, A.Covello0, V.Dimitrov, Jing-ye Zhang, X.L.Che, Z.Jang, D.Fong, A.Gelberg, I.Stefanescu, A.Gargano0, E.F.Jones, P.M.Gore, I.Y.Lee, G.M.Ter-Akopian, Yu.Ts.Oganessian, M.A.Stoyer, R.Donangelo, W.C.Ma, J.D.Cole, J.Kormicki, X.Q.Zhang, S.C.Wu, J.Gilat, T.N.Ginter, S.J.Asztalos0. New Insights into Frontier of Nuclear Structure of Neutronrich Nuclei by Means of Prompt Fission γ Ray Measurements at Gammasphere(II: Section 3 & Section 4)[J]. Nuclear Physics Review, 2010, 27(4): 363-389. doi: 10.11804/NuclPhysRev.27.04.363