Intermediate structure in the photoexcitation of Sem77, Brm79, and Bam137

J. J. Carroll, C. B. Collins, K. Heyde, M. Huber, P. von Neumann-Cosel, V. Yu. Ponomarev, D. G. Richmond, A. Richter, C. Schlegel, T. W. Sinor, and K. N. Taylor
Phys. Rev. C 48, 2238 – Published 1 November 1993
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Abstract

Continuing the systematic investigation into the photoexcitation of isomers over wide mass and energy ranges, the production of Sem77, Brm79, and Bam137 was studied with the bremsstrahlung facility at the superconducting Darmstadt linear accelerator. These isomers have half-lives on the order of seconds. Excitation functions were measured for the (γ,γ) reactions populating the metastable states for energies of 2–7 MeV and the important intermediate states were identified. Nuclear structure calculations with the quasiparticle-phonon model for Br79 and the particle- (hole-) core coupling approach for Ba137 gave satisfactory descriptions for the strength and position of the dominant mediating levels. Admixtures of fragmented outershell single-particle strength shifted to low energies were identified as essential features of the wave functions of those states. Intermediate states in Se77 displayed very large strengths compared to other isomers in the same mass region, providing further support for the correlation between integrated cross sections and ground state deformations recently discovered in the A=160–200 mass region. Such an enhancement would considerably improve the feasibility of a gamma-ray laser based on the sudden deexcitation of isomeric populations in deformed nuclei.

  • Received 28 June 1993

DOI:https://doi.org/10.1103/PhysRevC.48.2238

©1993 American Physical Society

Authors & Affiliations

J. J. Carroll, C. B. Collins, K. Heyde, M. Huber, P. von Neumann-Cosel, V. Yu. Ponomarev, D. G. Richmond, A. Richter, C. Schlegel, T. W. Sinor, and K. N. Taylor

  • Center for Quantum Electronics, The University of Texas at Dallas, P.O. Box 830688, Richardson, Texas 75083
  • Institute for Theoretical Physics, Proeftuinstraat 86, B-9000 Gent, Belgium
  • Institut für Kernphysik, Technische Hochschule Darmstadt, Schlossgartenstrasse 9, D-64289 Darmstadt, Germany
  • Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Head Post Office, P.O. Box 79, Moscow, Russia

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Vol. 48, Iss. 5 — November 1993

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