Collective vibrational states in even dysprosium nuclei

Grotdal, T.; Nybo, Kristie; Thorsteinsen, T.F.; Elbek, B.

doi:10.1016/0375-9474(68)90548-4

Cited by 91 publications

(21 citation statements)

References 13 publications

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“…Indeed, the J=7, 9 and 11 levels, in the E(J) versus J(J+ 1) diagram of Fig. 1, lie approximately on a straight line, which also passes close to the 3-and (5) states seen at 1367 and 1523 keV in a 156Dy(d, d')156Dy * experiment [27] and indicated by diamonds in Fig. 1: all these levels could then belong to the same rotational band, with negative parity, which would probably be of octupole nature.…”

Section: Discussionmentioning

confidence: 80%

“…The squares and triangles indicate the positions, in this diagram, of the 6 levels discovered in the present paper, with the tentative spin assignments discussed in the text. The diamonds correspond to octupole states [27] perimentally. Indeed, three explanations have been proposed for the nature of the perturbing band(s) responsible for the backbending: (1) an unpaired band into which the g.s.…”

Section: ~ 2 Statesmentioning

confidence: 99%

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Experimental evidence for low-spin members of ?upper? bands in156Dy

Masri¹,

Janssens²,

Michel³

et al. 1975

Z Physik A

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Abstract. Study of the energy levels of 156Dy through the 159Tb(p, 4n) 156Dy reaction has revealed the existence of six states with excitation energies between 1.8 and 2.8 MeV and spins between 6 and 12. Some of them can tentatively be assigned as low-spin members of "upper" bands which are thought to be responsible for the backbending phenomenon experimentally observed in the ground-state and //-vibrational bands of this nucleus. Others could be levels of a negative-parity octupole band.

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Section: Discussionmentioning

confidence: 80%

Section: ~ 2 Statesmentioning

confidence: 99%

Experimental evidence for low-spin members of ?upper? bands in156Dy

Masri¹,

Janssens²,

Michel³

et al. 1975

Z Physik A

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“…Taking into account the uncertainty of the experimental cross sections [9] and the normalization procedure, we can say that the spectroscopic factors calculated for the states with the spins 13/2, 9/2 and 1/2 (1/21 state) are in reasonable agreement with experiment. The 3/21 state, populated in the neutron transfer reactions [9], seems to have a more collective character than it results from the calculations. It deserves noting that the present calculations do not reproduce the position of the 3/22 state in a satisfactory way.…”

mentioning

confidence: 79%

“…The core-quasiparticle coupling model with the spherical basis allows us to obtain in a direct way the contribution of each core state to the given odd-A nucleus state. In Table 3 Table 4 the theoretical values of the spectroscopic factors are compared with the experimental ones which have been extracted from the (d, t) and (d, p) cross sections [9] by means of the DWBA procedure with parameters suitable for the A~150 region of nuclei [10]. Taking into account the uncertainty of the experimental cross sections [9] and the normalization procedure, we can say that the spectroscopic factors calculated for the states with the spins 13/2, 9/2 and 1/2 (1/21 state) are in reasonable agreement with experiment.…”

mentioning

confidence: 99%

“…In Table 3 Table 4 the theoretical values of the spectroscopic factors are compared with the experimental ones which have been extracted from the (d, t) and (d, p) cross sections [9] by means of the DWBA procedure with parameters suitable for the A~150 region of nuclei [10]. Taking into account the uncertainty of the experimental cross sections [9] and the normalization procedure, we can say that the spectroscopic factors calculated for the states with the spins 13/2, 9/2 and 1/2 (1/21 state) are in reasonable agreement with experiment. The 3/21 state, populated in the neutron transfer reactions [9], seems to have a more collective character than it results from the calculations.…”

mentioning

confidence: 99%

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156Dy as the core of157Dy

Chlebowska¹,

Jaskóła²

1983

Z Physik A

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The positive-parity energy levels in the 157Dy nucleus are analysed by means of the core-quasiparticle coupling model. The decoupled rotational band structure of the spectrum is reproduced by the theory. The collective components of the lSTDy levels are shown. The calculated pick-up and stripping spectroscopic factors are compared with experiment.In the lSVDy nucleus the positive-parity states are arranged in a decoupled rotational band. The lowest state in this band is a 9/2 + one, and above it there appear 5/2 +, 7/2 +, 3/2 +, 13/2 + states with a spacing between them smaller than 30 keV. In the higherspin part of the positive-parity band the favoured states with the spins 17/2, 21/2 and 25/2 are located below the unfavoured ones with the spins 15/2, 19/2 and 23/2, respectively. The experimental scheme of levels in ~STDy has been presented in [1] where also Coriolis calculations with a few fitted parameters have been performed. In the present study the core-quasiparticle coupling model of D6nau and Frauendorf [2] is employed to the analysis of the positive-parity energy levels in ~57Dy. In the considered model the nucleon-core interaction Hamiltonian comprises the reduced matrix elements of the collective multipole moment operators coupled to the corresponding reduced matrix elements for the odd nucleon (see e.g. [3][4][5]). Since the t57Dy nucleus shows quadrupole and hexadecapole deformations, the E2 and E4 reduced matrix elements for the transitions between collective states of the core nucleus must be estimated. For this purpose the symmetric rotor model is used. The energy matrix which has to be diagonalized is: where hoo=41A -l/a, r is the dimensionless radial coordinate of the odd neutron, ER is the energy of the core collective state IR), ej is the spherical single-neutron state energy, and J is the total angular momentum of the odd-A state. The deformation parameters f12 and f14 are determined from the relations: teraction is treated in terms of the BCS method applied to the solutions of (1) with ER=O. Next, the rotational Hamiltonian is diagonalized using the deformed quasiparticle states as basis. The pairing gap parameter, A, is assumed to be equal to 0.66 MeV. This value of A is in agreement with the self-consistent cranking model results [7]. The Fermi energy is fitted to the low-spin part of the level spectrum, the best fit being obtained when the Fermi level lies between the third and fourth levels of the i13/2 family of deformed orbitals. The single-neutron spherical energies used in the calculations are shown in Table 1. The experimental energies of

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Nuclear Data Sheets for A = 158

Helmer

1996

Nuclear Data Sheets

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Collective vibrational states in even dysprosium nuclei

Cited by 91 publications

References 13 publications

Experimental evidence for low-spin members of ?upper? bands in156Dy

Experimental evidence for low-spin members of ?upper? bands in156Dy

156Dy as the core of157Dy

Nuclear Data Sheets for A = 158

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