Crossings of the g-, s- and t-bands in 184Os

Shizuma, T.; Matsuura, K.; Jumatsu, T.; Hata, Kenji; Sasaki, Y.; Ishiyama, H.; Kato, Masayuki; Uchiyama, Köji; Komatsubara, T.; Furuno, K.; Hayakawa, Takehito

doi:10.1016/s0370-2693(98)01260-x

Cited by 22 publications

(15 citation statements)

References 15 publications

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“…In 180 W and 182 Os nuclei, it has been pointed out [1] that three levels, g-, s-and high-K(8 + ) bands, may cross in a certain angular momentum region (∼14h). A similar phenomenon was recently observed in the 184 Os nucleus involving the K = 10 + band [2]. The spectrum exhibiting signature inversion is implied to be caused by a rather strong inter-band interaction between such a high-K band and the s-band.…”

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confidence: 83%

Band crossing studied by GCM with 3D-CHFB

Horibata

Onishi

1999

J. Phys. G: Nucl. Part. Phys.

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In 180 W and 182 Os nuclei, it is pointed out [1] that three levels, g-, s-and high-K + (8 + ) bands may cross in a certain angular momentum region (∼ 14h). A similar phenomenon is recently observed in 184 Os nucleus involving K = 10 + band [2]. The spectrum exhibiting signature inversion is implied to be caused by a rather strong inter-band interaction between such a high-K band and s-band. With the intention of understanding the interband interaction, we have been studying the wobbling motion in terms of self-consistent three-dimensional cranked Hartree-Fock-Bogoliubov (3D-CHFB) calculation [3], together with the generator coordinate method (GCM) [4]. In the course of study, we found a stationary state of tilted axis rotation (TAR) in the 3D-CHFB solutions.In the previous calculation, we used a parameter set in which the pairing interaction for neutron and the quadrupole interaction were rather strong. Consequently the pairing of proton was destroyed before the neutron at the principal axis rotation (PAR). Although rotation alignment (RA) of high-j proton orbital was once speculated to give rise to the back-bending[5], the possibility was examined by successive experiments that it is due to neutron orbital.In this paper, we present results of an improved calculation of GCM based on the 3D-CHFB in the following two points. 1) We reduced the strength of neutron pairing interaction so as to make RA of neutron occur in PAR, which is considered to be yrast state. 2) We use the constrained GCM to obtain solutions in a more stable way. In a similar manner as the previous papers, we obtained PAR solutions by cranking up along x-axis perpendicular to the symmetry axis of the non-rotating state and also by cranking down along the axis. The two bands cross at J ∼ 20h in the present case.We tilted rotating axis along the prime-meridian, which intersects with z-and x-axis on the sphere of J = 18h. As well as our previous calculation, the existence of the stable TAR state is confirmed. The TAR minimum takes place at θ = 24• , and its depth is V TAR = −0.166MeV which is less than half of our previous value. In the TAR state, proton pairing is broken (s p -band) like the previous calculation, and hence level crossing occurs at least twice between the north-pole (or south-pole) and the PAR in the equatorial plane. We found the potential energy near the north-pole smaller than the value of PAR state.In order to study the inter-band interaction, the wobbling motion is investigated in terms of GCM taking the north and the south latitudes as a generator coordinate. Following the prescription described in ref. [6] in solving the GCM equation, the expectation values of the scalar of squared angular momentum vector J 2 and the particle numbers 1

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confidence: 83%

Band crossing studied by GCM with 3D-CHFB

Horibata

Onishi

1999

J. Phys. G: Nucl. Part. Phys.

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“…Hereafter we refer to the bands as high-K bands. Such bands as K π = 8 + (10 + ) are actually observed in the vicinity of the yrast line 2 in 180 W and 182 Os [1,2] ( 182 W and 184 Os [3,4]). It is characteristic that these bands have inter-band E2 transitions towards the yrast band having low-K configurations, namely these transitions violate the K-selection rule to a great extent (∆K ≃ K).…”

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confidence: 93%

“…A new interest in the "backbending" phenomenon has arisen through a series of experiments in 1990s' [1][2][3][4] for nuclei in the A ≃ 180 region. It is expected that the backbending in this mass region is caused by the three-bands crossing, i.e., the ground (g-), super (s-) and "tilt" (t-) bands [4,5], unlike the backbending caused by the two-bands crossing of the g-and s-bands [6] in light rare-earth nuclei. The t-band was recently proposed as "tilted rotational band" [7].…”

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confidence: 99%

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Wobbling motion in the multi-bands crossing region

Ansari

Horibata

et al. 2000

Physics Letters B

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The backbending in the A=180 mass region is expected to be caused by multi-bands crossing between low-K (g- and s-bands) and high-K bands. % We analyze a mechanism of coupling of these bands in terms of a dynamical treatment for nuclear rotations, i.e., the wobbling motion. The wobbling states are produced through the generator coordinate method after angular momentum projection, in which the intrinsic states are constructed through the 2d-cranked HFB calculations.Comment: 9 pages, 3 PS figures: to appear in Phys.Lett.

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“…[17], the degree of validity of the two-band-mixing approach. An interesting case for further clarification is 184 Os, where a phenomenological three-band-mixing analysis has been applied with considerable success [18], albeit with additional parameters, implying K ≈ 3.5 for the lowest energy I = 16 state, compared to K obs ≈ 8 found here. In addition, extension of the present two-band-mixing methodology to the A ≈ 130 deformed region, for example, might present problems due to competing proton and neutron s-band structures, and associated shape changes [19].…”

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confidence: 67%

Angular momentum orientation at bandcrossings in rotating nuclei

Walker¹

2006

J. Phys. G: Nucl. Part. Phys.

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Relative rotational E2 transition strengths are examined at bandcrossings, throughout the A ≈ 170 region of well deformed nuclei. It is inferred that for the crossing band (s band) the angular momentum projection on the nuclear symmetry axis follows closely the maximum value for the two singly occupied i 13/2 neutron orbitals adjacent to the Fermi surface. The method provides direct information from the experimental data about the orientation of the angular momentum vector relative to the intrinsic nuclear symmetry axis.

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Crossings of the g-, s- and t-bands in 184Os

Cited by 22 publications

References 15 publications

Band crossing studied by GCM with 3D-CHFB

Band crossing studied by GCM with 3D-CHFB

Wobbling motion in the multi-bands crossing region

Angular momentum orientation at bandcrossings in rotating nuclei

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