Electromagnetic properties of 161Tm at high spin

doi:10.1016/0375-9474(94)00810-A

Nuclear Physics A

Volume 587, Issue 1, 1 May 1995, Pages 150-180

https://doi.org/10.1016/0375-9474(94)00810-A Get rights and content

Abstract

The decay of the yrast and near-yrast high-spin states in ¹⁶¹Tm has been observed following the reaction ¹²⁸Te(³⁷Cl,4n). Extension of the known level scheme reveals previously unobserved crossings in the bands built on the $72^{−} [523]$ , $72^{+} [404]$ and $12^{−} [541]$ Nilsson states. The use of both gold- and terbium-backed targets has enabled the measurement by the Doppler shift attenuation method of lifetimes of states in the $h_{112}$ yrast band in the spin range $412 ⩽ I ⩽ 672$ . The results show little evidence for change in the nuclear deformation over this interval in spin (Q_t ≈ 6 eb). From lifetime measurements and $B(M1) B(E2)$ values in the $h_{112}$ band, absolute B(M1) values for five transitions (for states with $412 ⩽ I ⩽ 512$ ) were determined. These results provide some evidence for a reduction in the proton spin projection on the deformation axis relative to its value at low rotational frequency. The signature splitting in the Routhians and $B(M1) B(E2)$ values for the $h_{112}$ band is discussed in terms of the inclusion of non-axially-symmetric (γ-deformed) components in the nuclear wavefunction.

References (43)

P.J. Twin et al.
Nucl. Phys. A
(1983)
C. Ekström et al.
Nucl. Phys. A
(1971)
I. Adam et al.
Nucl. Phys. A
(1981)
C. Foin et al.
Nucl. Phys. A
(1984)
W.M. Currie
Nucl. Instr. Meth.
(1969)
J. Gascon et al.
Nucl. Phys. A
(1990)
W. Nazarewicz et al.
Nucl. Phys. A
(1985)
W. Nazarewicz et al.
Nucl. Phys. A
(1990)
G.B. Hagemann et al.
Nucl. Phys. A
(1984)
D.C. Radford et al.
Nucl. Phys. A
(1992)

C-H. Yu et al.

Nucl. Phys. A

(1990)

K. Theine et al.

Nucl. Phys. A

(1992)

S.G. Li et al.

Nucl. Phys. A

(1993)

J.C. Bacelar et al.

Nucl. Phys. A

(1985)

R.A. Bark et al.

Nucl. Phys. A

(1989)

C.X. Yang et al.

Phys. Lett. B

(1983)

R. Nordhagen et al.

Nucl. Phys. A

(1970)

J. Gascon et al.

Nucl. Phys. A

(1987)

C-H. Yu et al.

Nucl. Phys. A

(1988)

W. Schmitz et al.

Nucl. Phys. A

(1992)

P. Frandsen et al.

Phys. Lett. B

(1986)

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Nuclear Data Sheets for A = 161
2011, Nuclear Data Sheets
The experimental results from the various reaction and radioactive decay studies leading to nuclides in the A=161 mass chain have been reviewed. Nuclides ranging from Sm (Z=62) through Os (Z=76) are included, with Os being a new entry based on a recently reported study. These data are summarized and presented, together with adopted level schemes and properties. This work supersedes the previous evaluation (2000Re14) of the data on these nuclides.
General properties of the πh<inf>9/2</inf>[541]1/2- configuration and level scheme of 165Tm
2001, Nuclear Physics A
¹⁶⁵Tm has been studied through the reactions ¹⁵⁰Nd(¹⁹F, 4n), E_beam=85 MeV and ¹⁵⁴Sm (¹⁵N, 4n), E_beam=70 MeV. The level scheme has been extended to spin 71/2⁻ℏ, and four new bands have been added. Two are assigned to the K=17/2, three-quasiparticle configurations, π[523]7/2⁻⊗ν[642]5/2⁺⊗ν[523]5/2⁻ and π[404]7/2⁺⊗ν[642]5/2⁺⊗ν[523]5/2⁻, and the remaining two are assigned to γ-vibrations coupled to an h_9/2 proton. Lifetimes of high-spin states in the [541]1/2⁻ and [411]1/2⁺ bands have been measured using DSAM techniques, allowing transition quadrupole moments to be deduced. Furthermore, crossings between the [541]1/2⁻ and [523]7/2⁻ bands and between the [411]1/2⁺ and [404]7/2⁺ bands are analysed with a band-mixing calculation to obtain the quadrupole moments of the [523]7/2⁻ and [404]7/2⁺ bands. While the [523]7/2⁻, [411]1/2⁺ and [404]7/2⁺ bands all have similar deformations, the [541]1/2⁻ band has a quadrupole moment approximately 15% larger. The relative deformations are in good agreement with diabatic potential energy surface calculations performed using the code “Ultimate Cranker”. The experimental crossing frequency, due to the alignment of i_13/2 neutrons, is found to be delayed in the [541]1/2⁻ band compared to the other bands. This is a universal feature in the rare-earth region, and extensive systematic Cranked Shell Model calculations have been performed to predict deformations and crossing frequencies for nuclei in the region. The model is unable to reproduce the full delay in crossing frequency, confirming that deformation alone is not responsible for the shift.
Nuclear data sheets for A = 161
2000, Nuclear Data Sheets
Structure of excited bands in 162Tm and residual interactions
1998, Nuclear Physics A
The nucleus ¹⁶²Tm has been populated by the ¹³⁰Te(³⁷Cl,5n) reaction, and the γ-cascades detected with the NORDBALL array. Eight coupled rotational bands involving the proton orbitals, $g_{72} [404] 72^{+}$ , $d_{32} [411] 12^{+}$ , $d_{52} [402] 52^{+}$ , $h_{112} [523] 72^{−}$ and $h_{92} [541] 12^{−}$ and neutron orbitals $i_{132} [642] 52^{+}$ , $h_{92} [523] 52^{−}$ and $f_{72} [521] 32^{−}$ have been established in ¹⁶²Tm, to spins varying from 18 to 47ℏ. Various phenomena which can be related to residual neutron-proton interactions are discussed. In particular, signature inversion in the $π [541]1 2^{−} ⊗ ν [642]5 2^{+}$ bands based on the $h_{92}$ quasiproton and $i_{132}$ quasineutron, rewpectively, may be explained by a fairly large p-n interaction. In addition, interactions at the crossings of bands with constituent quasiparticles differing both in parity and signature have been extracted with strength of the order of a few (4–12) keV. Such interactions also require terms beyond the standard mean field description.
Band crossings and signature splitting in 159Ho
2000, Journal of Physics G: Nuclear and Particle Physics
Triaxial strongly deformed bands in Tm160,161
2008, Physical Review C - Nuclear Physics

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¹: Present address: Department of Physics, University of Paisley, Paisley PA1 2BE, Scotland.

²: Permanent address: Institute of Atomic Energy, P.O. Box 275, Beijing, Peoples' Republic of China.

³: On leave from University of São Paulo, Brazil.

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Nuclear Physics A

Abstract

References (43)

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Nucl. Instr. Meth.

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Phys. Lett. B

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Nucl. Phys. A

Phys. Lett. B

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Nuclear Data Sheets for A = 161

General properties of the πh<inf>9/2</inf>[541]1/2<sup>-</sup> configuration and level scheme of <sup>165</sup>Tm

Nuclear data sheets for A = 161

Structure of excited bands in <sup>162</sup>Tm and residual interactions

Band crossings and signature splitting in <sup>159</sup>Ho

Triaxial strongly deformed bands in Tm160,161