Recoil distance lifetime measurements in Sm146

S. Rozak, E. G. Funk, and J. W. Mihelich
Phys. Rev. C 25, 3000 – Published 1 June 1982
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Abstract

Recoil-distance lifetime measurements of levels in Sm146 have been carried out using the (B11,4n) reaction at 54 MeV on natural La targets evaporated on gold. The data were analyzed using a computer code which treats complex cascade feeding in a rigorous formalism. The following lifetimes have been measured (energy is in keV and spin parity are in parentheses): 1811.5(6+), 12570+140 ps; 2600.3(7), 16±6 ps; 2737.1(8+), 16.4±6.0 ps; 2797.6(9), 1.200.19+0.29 ns; 3354.5(9), 396+7 ps; 3783.5(11), 155+6 ps; 4091.2(11), 7.11.9+2.1 ps; 4628.8(13), 7.62.9+3.3 ps. Lifetimes have also been measured for the 747.2(2+), 1381.2(4+), and 4461.4(12) states but with considerably less precision. The results support the interpretation of the yrast odd-spin negative parity states (3 through 11) as being described by an octupole phonon coupled to the 0+ through 8+ yrast even-spin, positive-parity "ground-state band" states. The results for the 2+ through 8+ states are compared to calculations of the interacting boson approximation model and cluster-vibrator model. Both models are not inconsistent with the observed transition probabilities up to the 6+4+ transition, but fail to reproduce that for the 8+6+ transition. Our results support spin-parity arrangements of 12 and 13 for the 4461 and 4629 keV states, respectively.

NUCLEAR REACTIONS La139(B11,4n), E=54 MeV; measured recoil-distance Doppler shift. Sm146 levels, deduced lifetimes, reduced transition probabilities. Ge(Li) detectors, plunger.

  • Received 29 October 1981

DOI:https://doi.org/10.1103/PhysRevC.25.3000

©1982 American Physical Society

Authors & Affiliations

S. Rozak*, E. G. Funk, and J. W. Mihelich

  • Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556

  • *Present address: U. S. Nuclear Regularoty Commission, Glen Ellyn, Illinois.

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Vol. 25, Iss. 6 — June 1982

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