Rotational energy expressions and least-squares fitting of backbenders and similar nuclei

doi:10.1016/0375-9474(79)90096-4

Nuclear Physics A

Volume 332, Issues 1–2, 3–10 December 1979, Pages 82-94

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Abstract

The backbending or irregularities of band spacings of states near the yrast line were fit using simple rotational energy expressions which include band mixing of the yrast and yrare states. In our model the sharp backbending requires two large mixing terms, a spin-independent term arising from the pairing interaction and a Coriolis coupling term. Least-squares fitting of backbenders in the deformed even-even nuclei indicate a near cancellation of the mixing matrix elements near the virtual band crossing. Although the idealized and simplified expressions for the backbending spin in terms of the pairing gap Δ, high-j orbital spacing, high-j Coriolis matrix element J_tT, and moment of inertia I may not be quantitatively correct, they do indicate the general conditions required for backbending.

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The ¹⁶²Dy(α, 2nγ) and ¹⁶⁵Ho(p, 2nγ) reactions were used to populate intermediate-spin levels of the rotational side-bands of the N = 96 nucleus ¹⁶⁴Er. The β- and γ-bands and two (K^π = 0⁻ and 2⁻) octupole vibrational bands were observed from the bandheads at high spin (10–14 ħ). In addition, four two-quasiparticle bands were observed, the $v(i_{132})^{2}$ S-band, a K^π = 4⁺ band, and two negative-parity bands (K^π = 5⁻ and 7⁻). Extensive interactions were observed among the bands of both parities. The S-band crosses the β-, γ-, and g.s. bands while the K^π = 5⁻ band crosses both octupole bands. Interaction strengths at these crossings are inferred using a two band mixing analysis. The results are discussed in terms of the rotation-alignment picture.
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^☆: This work was supported by US Dept. of Energy and the US National Science Foundation.

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Nuclear Physics A

Abstract

References (11)

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Cited by (7)

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Simple model for backbending

Rotational energy expressions and least-squares fitting of backbenders and similar nuclei☆

Abstract

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