Nature of the lowest excited<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="italic">K</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">π</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math>=<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>states of even-even deformed n

Dg, Burke; Sood, P. C.

doi:10.1103/physrevc.51.3525

Cited by 27 publications

(15 citation statements)

References 13 publications

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“…The DDM [10] indicates that the lowest lying 0 1 states in 164 168 Er are two-g phonon in nature. This possibility was also suggested recently by Casten and von Brentano [13] based on sd-IBM (interacting boson model) calculations, but was challenged by Burke and Sood [14] and by Günther et al [15]. Therefore, evidence of the existence of the 0 1 gg state and its location can yield important information, not only on the values of various parameters needed for models, but also as a much more sensitive test of different model approaches than the 4 1 gg state.…”

mentioning

confidence: 91%

Kπ=0+and
Garrett
¹
,
Kadi
²
,
Li
³

et al. 1997
Phys. Rev. Lett.
82
4
46
0
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The ͑n, n 0 g͒ reaction has been used to search for two-phonon g-vibrational states in 166 Er. Levels at 1943 and 2028 keV have been observed with collective transitions to the g band. The latter, which has B͑E2; 2028 ! 2 1 g ͒ 7.4 6 2.5 W.u. (Weisskopf unit) is interpreted as the I, K p 4, 4 1 twog-phonon state. The former, for which the data indicate spin 0, has B͑E2; 1943 ! 2 1 g ͒ 21 6 6 W.u. and is interpreted as the I, K p 0, 0 1 two-g-phonon state. This is the first observation of the K p 0 1 two-g-phonon state in a well-deformed nucleus, and its identification places stringent limits on the nuclear models. [S0031-9007(97)03409-1] PACS numbers: 21.10.Tg, 23.20.En, 25.40.Fq, 27.70. + q The existence of two-phonon states in deformed nuclei has been the subject of considerable debate for over 30 years. The recent measurement [1] of enhanced E2 transitions from a level at 2055 keV in 168 Er, interpreted as the K p 4 1 two-phonon g vibration ͑4 1 gg ͒, has not silenced the controversy which is now centered on the magnitude of the two-g-phonon component in the wave function needed to reproduce the enhanced E2 rate and the extent to which these states appear in other nuclei [2][3][4][5][6][7]. Following the discovery of the 4 1 gg state in 168 Er, attempts [2] were made to locate candidates for these states in other nuclei, mainly by considering branching ratios and energy systematics. For many of these candidates, Burke [3] has argued that data exist which rule out the possibility that the main components in their wave functions are of two-phonon character. This demonstrated the need for absolute B͑E2͒-value measurements and for considering all data before assigning levels as two-phonon states.Certain models, such as the self-consistent collectivecoordinate model (SCCM) [8], the multiphonon method (MPM) [9], the dynamic-deformation model (DDM) [10], etc., predict that states with properties of 4 1 gg states should be widespread in the well-deformed rare-earth region. The quasiparticle-phonon nuclear model (QPNM) [4], on the other hand, predicts that 4 1 gg states should exist in a few special cases only, such as 164 Dy, 166 Er, and 168 Er. This limited set of nuclei arises from the behavior of the density of levels in the vicinity of the 4 1 gg states; these nuclei are predicted as being the only ones for which the density is sufficiently low that the two-gphonon states are not greatly fragmented.A feature common to many models is that they predict a relatively pure K p 0 1 two-phonon g vibration ͑0 1 gg ͒ should not exist. Bohr and Mottelson [11] suggested that for 168 Er these states should lie above the 4 1 gg excitation, in the vicinity of 2.5 MeV. In a more detailed treatment, Dumitrescu and Hamamoto [12] found that the positions of the two-g-phonon states depended on the anharmonicities introduced into the Hamiltonian. In particular, by introducing a g-dependent contribution to the moment of inertia, the 0 1 gg excitation could lie lower than the 4 1 gg state.As well, the introduction of a g-unstable ...

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mentioning

confidence: 91%

Kπ=0+and
Garrett
¹
,
Kadi
²
,
Li
³

et al. 1997
Phys. Rev. Lett.
82
4
46
0
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“…Traditionally, the first excited K π = 0 + states and the first excited 2 + states are interpreted, respectively, as the β and γ vibrational states. While the 2 + collective excitations are better understood theoretically, the nature of the lowest 0 + excitation of deformed nuclei still remains under debate [3,4,5,6,7]. The physics of higher 0 + states is even more complex because, on one side, they can predominantly be multi-phonon states based on the single-phonons [8], and on the other side, they can be quasiparticle (qp) excitations in nature.…”

mentioning

confidence: 99%

Nature of excited0+states inGd158described by the projected shell model

et al. 2003

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Excited 0 + states are studied in the framework of the projected shell model, aiming at understanding the nature of these states in deformed nuclei in general, and the recently observed 13 excited 0 + states in 158 Gd in particular. The model, which contains projected two-and four-quasiparticle states as building blocks in the basis, is able to reproduce reasonably well the energies for all the observed 0 + states. The obtained B(E2) values however tend to suggest that these 0 + states might have a mixed nature of quasiparticle excitations coupled to collective vibrations.PACS numbers: 21.60. Cs, 23.20.Lv, 27.70.+q Dynamic perturbations of nuclear shapes around the equilibrium can give rise to physical states at low to moderate excitation energies. Classical examples of such motion are β and γ vibrations [1,2], in which nucleons undergo vibrations in a collective manner. Traditionally, the first excited K π = 0 + states and the first excited 2 + states are interpreted, respectively, as the β and γ vibrational states. While the 2 + collective excitations are better understood theoretically, the nature of the lowest 0 + excitation of deformed nuclei still remains under debate [3,4,5,6,7]. The physics of higher 0 + states is even more complex because, on one side, they can predominantly be multi-phonon states based on the single-phonons [8], and on the other side, they can be quasiparticle (qp) excitations in nature. The real situation is, perhaps, that the two aspects, collective excitations and qp states, are mixed by residual interactions.Data on K π = 0 + states have been relatively sparse. In a very recent work by Lesher et. al.[9], a remarkable (p, t) experiment revealed a total of 13 excited 0 + states in 158 Gd, below an excitation energy of approximately 3.1 MeV. This abundance of 0 + states in a single nucleus provides significant new information on the poorly understood phenomenon, which has immediately sparked off theoretical interest. For this energy range, one may think about an explanation through collective modes. In fact, Zamfir, Zhang, and Casten [10] suggested that many of the observed 0 + states may be of two-phonon octupole character. Nevertheless, these authors warned also that, although the mechanism was excluded in their collective models, many of the 0 + states in this excitation energy range may be predominantly two-qp in character.The purpose of the present paper is to investigate whether one can explain the nature of the observed 0 + states in terms of qp excitations. In contrast to Ref.[10], our calculation here does not emphasize the aspect of collective excitation. Although, similar to the work of Zamfir, Zhang, and Casten [10], we may provide only a partial image, our results may shed light on the importance of considering the qp aspects in understanding the nature of these 0 + states.Our study is based on the projected shell model (PSM)[11]. The PSM is the spherical shell model built on a deformed basis. The PSM calculation usually begins with the deformed Nilsson single-particle...

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“…This is particularly pronounced in the middle of the shell ͑10Ͻ N Ͻ 22͒, where one finds well-deformed nuclei. To deduce common features, we focused our attention on the welldeformed nuclei from the lanthanide region as these nuclei present some interesting challenges [13] from a theoretical as well as from an experimental point of view [14].…”

Section: Empirical Investigation Of Thementioning

confidence: 99%

“…To understand this behavior, one must probe more deeply into the microscopic structure of these nuclei [13]. In the present work, the properties of the low-lying spectra of deformed even-even nuclei are reproduced and explained by applying a proton-neutron version of the algebraic shell model with pseudo-SU(3) symmetry [7].…”

Section: Empirical Investigation Of Thementioning

confidence: 99%

Systematics in the structure of low-lying, nonyrast bandhead configurations of strongly deformed nuclei

2004

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An empirical investigation of the trends in the properties of the nonyrast K =2 ␥ + and K =0 2 + bandhead configurations in nuclei that are related to one another through the addition or removal of ␣-particle-like structures, reveals their complex and changing behavior in contrast to the smooth behavior of the yrast states. A systematic application of the pseudo-SU(3) model for such a sequence of deformed nuclei from the rare earth region leads to an accurate and unified description of not only yrast, but nonyrast collective bands. The onset of deformation as manifested through the position of the excited bandheads in the spectra is understood and interpreted by using a realistic model Hamiltonian in conjunction with a microscopic distribution of the eigenstates across allowed proton and neutron strong-coupled SU (3) configurations.

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Nature of the lowest excitedKπ=0+states of even-even deformed n

Cited by 27 publications

References 13 publications

Kπ=0+and
Garrett
¹
,
Kadi
²
,
Li
³

et al. 1997
Phys. Rev. Lett.
82
4
46
0
View full text Add to dashboard Cite

Kπ=0+and
Garrett
¹
,
Kadi
²
,
Li
³

et al. 1997
Phys. Rev. Lett.
82
4
46
0
View full text Add to dashboard Cite

Nature of excited0+states inGd158described by the projected shell model

Systematics in the structure of low-lying, nonyrast bandhead configurations of strongly deformed nuclei

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Nature of the lowest excitedKπ=0+states of even-even deformed n

Cited by 27 publications

References 13 publications

Kπ=0+andGarrett1, Kadi2, Li3 et al. 1997Phys. Rev. Lett.824460View full textAdd to dashboardCite

Kπ=0+andGarrett1, Kadi2, Li3 et al. 1997Phys. Rev. Lett.824460View full textAdd to dashboardCite

Nature of excited0+states inGd158described by the projected shell model

Systematics in the structure of low-lying, nonyrast bandhead configurations of strongly deformed nuclei

Contact Info

Product

Resources

About

Kπ=0+and
Garrett
¹
,
Kadi
²
,
Li
³

et al. 1997
Phys. Rev. Lett.
82
4
46
0
View full text Add to dashboard Cite

Kπ=0+and
Garrett
¹
,
Kadi
²
,
Li
³

et al. 1997
Phys. Rev. Lett.
82
4
46
0
View full text Add to dashboard Cite