Negative-parity yrast band in 170Yb: Rotation-aligned neutrons with deformation-coupled bandhead?

doi:10.1016/0370-2693(79)90608-7

Physics Letters B

Volume 86, Issue 1, 10 September 1979, Pages 9-12

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Abstract

A sideband in ¹⁷⁰Yb has been identified up to I^π=17⁻. It has an isomeric I=4 bandhead, yet the odd-spin states have prompt branches to the ground-state band. The contrasting properties are explained by the Coriolis effects on the quasi-particle configuration.

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Nuclear Data Sheets for A=170
2018, Nuclear Data Sheets
Nuclear structure data pertaining to all nuclei with mass number A=170 have been evaluated, and incorporated into the ENSDF data file. This evaluation supersedes the previous evaluation (Coral M. Baglin), Nuclear Data Sheets 96, 611 (2002), (cutoff date 15 August 2002) and subsequent updates of the ENSDF file for Yb to Dy (cutoff 15 April 2010), Lu (cutoff 8 October 1998), Pt (cutoff 17 February 1999) and Ta, Os (cutoff 7 April 1998). Since the previous evaluation, ¹⁷⁰Gd has been observed and the ground state T_1/2 measured. New excited states have also been observed in the neutron rich ¹⁷⁰Dy. The ground state T_1/2 of ¹⁷⁰Tb has been determined, however, there are currently still no excited states observed in this nucleus. There remains some uncertainty in the ground state and longer-lived isomer in ¹⁷⁰Ir which could warrent further experimental investigation.
Nuclear Data Sheets for A = 170
1987, Nuclear Data Sheets
The 1975 Nuclear Data Sheets for A=170 (75Sc26) have been revised on the basis of experimental reaction and decay data by the cutoff date noted below. The detailed level schemes and decay schemes, and experimental reaction and decay data on which they are based are presented for all nuclei with mass number A=170. The experimental data are evaluated; the inconsistencies and discrepancies are noted; and adopted values for levels and γ-ray energies, γ-ray intensities, as well as for other nuclear properties are given.
Transition probabilities between two-quasiparticle configurations in 170, 172Yb and 182W
1983, Nuclear Physics, Section A
Applying the generalized centroid-shift method in (α, 2n) reactions, the following half-lives of 2q.p. states have been measured: $T_{12} (1375.8 keV) = 0.20 ± 0.07 ns$ , $T_{12} (1640.8 keV) = 0.5 ± 0.2 ns$ , $T_{12} (2689.5 keV) = 0.7 ± 0.1 ns (^{172} Yb)$ ; $T_{12} (2189.9 keV) = 2.2 ± 0.3 ns$ , $T_{12} (1851.5 keV) < 0.2 ns (^{170} Yb)$ ; $T_{12} (100.1 keV) = 1.4 ± 0.2 ns$ , $T_{12} (1809.7 keV) = 0.25 ± 0.10 ns$ , $T_{12} (1829.5 keV) = 0.25 ± 0.10 ns$ , $T_{12} (1756.8 keV) < 0.5 ns (^{182} W)$ . The experimental E1, M1 and E2 transition rates are compared to calculations within the Nilsson-plus-pairing model. The band-head K^π = 4⁻ of a semi-aligned band in ¹⁷²Yb appears as a deformation-aligned 2q.p. configuration. The E2 transition rates indicate configuration mixing between the 2q.p. K^π = 4⁻, 5⁻ and 6⁻ states in ¹⁸²W.
Band crossing in 162Dy: Characterisation of negative-parity yrast and yrare sequences
1981, Physics Letters B
Rotational bands in 170Yb observed following (α,xn) reactions
1981, Nuclear Physics, Section A
At least seven side bands, with K^π = (0⁺), (1⁻), (2⁺), (3⁻), 4⁻, 6⁻, and 7⁻, have been identified in ¹⁷⁰Yb up to high spin, using γ-ray techniques following (α, 2n) and (α, 4n) reactions. Backbending in the positive-parity yrast band is confirmed, and candidates for low-spin members of the S-band are found. The negative-parity yrast band has behaviour characteristic of both strong coupling and decoupling. These properties, together with those in the other negative-parity side bands, are interpreted as arising from Coriolis effects on the quasiparticle configurations, and the experimental results are compared with a two-quasipartiele-plus-rotor calculation. Evidence of ΔK = 2 mixing is found in the K = (3) side band. The relationship between the moments of inertia of the positiveparity and negative-parity yrast bands in the N = 100 isotones is discussed in the framework of a simple empirical model, giving insight into the presence or absence of backbending. The negativeparity yrast bands in the N = 100 isotones are compared. Their significant differences are qualitatively reprodued in two-quasiparticle-plus-rotor calculations.
A study of 172Yb following the 170Er(α, 2n) reaction
1980, Nuclear Physics, Section A
Six side bands have been identified up to high spin in ¹⁷²Yb. Four of these, with K^π = 1⁻, 4⁻, 6⁻ and possibly 9⁻, involve an $i_{132}$ neutron, and have high moments of inertia. The properties of these bands are reproduced in a two-quasiparticle-plus-rotor Coriolis coupling calculation. A well-known band with K^π = 3^+; is extended to I = 14; its properties suggest a mixed neutron-proton configuration. The first excited K^π = 0⁺ band is extended to I = 14. It has a rapidly rising moment of inertia, and is predicted to cross the g.s.b. at about I = 20⁺. These K = 0⁺ states could be the low-spin members of an $(i_{132})^{2}$ band.

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Physics Letters B

Abstract

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Cited by (10)

Nuclear Data Sheets for A=170

Nuclear Data Sheets for A = 170

Transition probabilities between two-quasiparticle configurations in <sup>170, 172</sup>Yb and <sup>182</sup>W

Band crossing in <sup>162</sup>Dy: Characterisation of negative-parity yrast and yrare sequences

Rotational bands in <sup>170</sup>Yb observed following (α,xn) reactions

A study of <sup>172</sup>Yb following the <sup>170</sup>Er(α, 2n) reaction