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Title: Detailed high-spin spectroscopy and the search for the wobbling mode in {sup 171}Ta

Abstract

High-spin states in {sup 171}Ta were populated in the {sup 124}Sn({sup 51}V,4n) reaction at 228 MeV to search for evidence of stable triaxial deformation. Identification of a wobbling sequence based on the previously known {pi}i{sub 13/2} structure would provide a unique signature for this rarely observed shape. No such sequence was identified in these data, which suggests that the island of triaxial strongly deformed bands may be smaller than once thought. However, over 200 new transitions and two new bands were placed in the level scheme and the sequence based on the {pi}i{sub 13/2} orbital could be observed up to spin and parity I{sup {pi}}=(101/2{sup +}). The relative excitations of all the sequences were determined and the ground state of {sup 171}Ta was found to have 5/2{sup +} quantum numbers, contrary to previous reports. All of the previously known structures were extended to much higher spin and their high-frequency band crossings are interpreted within the framework of the cranked shell model.

Authors:
; ;  [1]
  1. Department of Physics, U.S. Naval Academy, Annapolis, Maryland 21402 (United States) (and others)
Publication Date:
OSTI Identifier:
20771101
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 72; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevC.72.064325; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; EXCITATION; GROUND STATES; HIGH SPIN STATES; MEV RANGE; NUCLEAR DEFORMATION; NUCLEAR STRUCTURE; PARITY; QUANTUM NUMBERS; SHELL MODELS; SPECTROSCOPY; SPIN; TANTALUM 171; TIN 124; VANADIUM 51

Citation Formats

Hartley, D J., Mohr, W.H., and Vanhoy, J.R. Detailed high-spin spectroscopy and the search for the wobbling mode in {sup 171}Ta. United States: N. p., 2005. Web. doi:10.1103/PhysRevC.72.064325.
Hartley, D J., Mohr, W.H., & Vanhoy, J.R. Detailed high-spin spectroscopy and the search for the wobbling mode in {sup 171}Ta. United States. doi:10.1103/PhysRevC.72.064325.
Hartley, D J., Mohr, W.H., and Vanhoy, J.R. Thu . "Detailed high-spin spectroscopy and the search for the wobbling mode in {sup 171}Ta". United States. doi:10.1103/PhysRevC.72.064325.
@article{osti_20771101,
title = {Detailed high-spin spectroscopy and the search for the wobbling mode in {sup 171}Ta},
author = {Hartley, D J. and Mohr, W.H. and Vanhoy, J.R.},
abstractNote = {High-spin states in {sup 171}Ta were populated in the {sup 124}Sn({sup 51}V,4n) reaction at 228 MeV to search for evidence of stable triaxial deformation. Identification of a wobbling sequence based on the previously known {pi}i{sub 13/2} structure would provide a unique signature for this rarely observed shape. No such sequence was identified in these data, which suggests that the island of triaxial strongly deformed bands may be smaller than once thought. However, over 200 new transitions and two new bands were placed in the level scheme and the sequence based on the {pi}i{sub 13/2} orbital could be observed up to spin and parity I{sup {pi}}=(101/2{sup +}). The relative excitations of all the sequences were determined and the ground state of {sup 171}Ta was found to have 5/2{sup +} quantum numbers, contrary to previous reports. All of the previously known structures were extended to much higher spin and their high-frequency band crossings are interpreted within the framework of the cranked shell model.},
doi = {10.1103/PhysRevC.72.064325},
journal = {Physical Review. C, Nuclear Physics},
number = 6,
volume = 72,
place = {United States},
year = {Thu Dec 15 00:00:00 EST 2005},
month = {Thu Dec 15 00:00:00 EST 2005}
}
  • Cited by 9
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  • The collective wobbling mode, the strongest signature for the rotation of a triaxial nucleus, has previously been seen only in a few Lu isotopes in spite of extensive searches in nearby isotopes. A sequence of transitions in the N = 94 {sup 167}Ta nucleus exhibiting features similar to those attributed to the wobbling bands in the Lu nuclei has now been found. This band feeds into the {pi}/{sub 13/2} band at a relative energy similar to that seen in the established wobbling bands and its dynamic moment of inertia and alignment properties are nearly identical to the /{sub 13/2} structuremore » over a significant frequency range. Given these characteristics, it is likely that the wobbling mode has been observed for the first time in a nucleus other than Lu, making this collective motion a more general phenomenon.« less
  • Excited states in the neutron-deficient nucleus {sup 167}Ta were studied through the {sup 120}Sn({sup 51}V,4n) reaction. Twelve rotational bands have been observed and the relative excitation energy of each sequence is now known owing to the multiple interband connections. Several quasineutron alignments were observed that aided in the quasiparticle assignments of these bands. The resulting interpretation is in line with observations in neighboring nuclei. Trends in the wobbling phonon energy seen in {sup 161,163,165,167}Lu and {sup 167}Ta are also discussed and particle-rotor model calculations (assuming constant moments of inertia) are found to be inconsistent with the experimental data.
  • The collective wobbling mode, the strongest signature for the rotation of a triaxial nucleus, has previously been seen only in a few Lu isotopes in spite of extensive searches in nearby isotopes. A sequence of transitions in the N=94 {sup 167}Ta nucleus exhibiting features similar to those attributed to the wobbling bands in the Lu nuclei has now been found. This band feeds into the {pi}i{sub 13/2} band at a relative energy similar to that seen in the established wobbling bands and its dynamic moment of inertia and alignment properties are nearly identical to the i{sub 13/2} structure over amore » significant frequency range. Given these characteristics, it is likely that the wobbling mode has been observed for the first time in a nucleus other than Lu, making this collective motion a more general phenomenon.« less