M. Waroquier

Coexistence in odd-mass nuclei

K. Heyde, P. Van Isacker, M. Waroquier, L.J. Wood, R.A. Meyer
Physics Reports
102 (5-6), 291-393
1983
A1
Published while none of the authors were employed at the CMM

Abstract 

Shape coexistence in odd-mass nuclei near closed shells (±1 and ±3 nucleons) is reviewed. Two main approaches are presented. The more historical one starts from the explicit introduction of a deformation degree of freedom and allows particular Nilsson orbitals to occur very low in excitation energy. A second approach starts from spherical particle-hole (p-h) excitations across a closed shell and allows interactions with quadrupole vibrations of the underlying core nucleus. The equivalence between the two approaches is discussed in some detail. Attention is given also to other approaches to the description of coexistence. A detailed review of the experimental evidence for coexistence in odd-mass nuclei near the Z = 28, 50, 82 and N = 28, 50, 82 closed shells is made. In addition, the fingerprints of coexisting states, i.e. the most pronounced nuclear structure properties characterizing such states, are presented. These fingerprints provide a necessary (though not sufficient) set of conditions for identifying coexistence throughout the nuclear mass table. At the end, we briefly describe the connection of the present study to other areas of nuclear structure such as related configurations in doubly-even nuclei, many-particle many-hole excitations, deep-lying hole states, and the possibility of incorporating these degrees of freedom into an Interacting Boson Approximation (IBA) framework. A major conclusion of this review is that there is a clear connection between shape coexistence and shell-model intruder states. A variety of topics is suggested for future experimental and theoretical investigation.

The importance of intruder states in 114Cd

K. Schreckenbach, A. Mheemeed, G. Barreau, T. von Egidy, H.R. Faust, H.G. Börner, R. Brissot, K. Heyde, P. Van Isacker, M. Waroquier, G. Wenes
Physics Letters B
110 (5), 364-368
1982
A1
Published while none of the authors were employed at the CMM

Abstract 

The origin and decay properties of levels in 114Cd, with special emphasis on the quintuplet of states around 1.2 MeV excitation energy, are invesigated both theoretically and experimentally. An almost complete set of reduced transition probabilities B(E0) and B(E2) is established by means of (n, γ) and (n, e−) spectroscopy. Cofiguration mixing between vibrational-like and rotational-like states, extracted from proton two-particle-two-hole (2p-2h) core coupling calculations, is found to be crucial for explaining the peculiar level properties.

The hexadecapole degree of freedom in rotational nuclei

P. Van Isacker, K. Heyde, M. Waroquier, G. Wenes
Physics Letters B
104 (1), 5-10
1981
A1
Published while none of the authors were employed at the CMM

Abstract 

We present a new description of the hexadecapole degree of freedom in nuclei in the framework of the Interacting Boson Model, by the addition of a g boson. Results of this model are presented concerning E2 transitions in 156Gd. Also, the problem of the importance of the L = 4 degree of freedom in the low-lying collective spectrum of rotational nuclei is studied.

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