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Etude de la coexistence de formes dans les isotopes légers du krypton et du sélénium par excitation Coulombienne de faisceaux radioactifs

Abstract : Deformation from the spherical shape is a fundamental property of the atomic nuclei. The light krypton isotopes show two minima in their potential energy corresponding to elongated (prolate) and compressed (oblate) quadrupole deformation. Both configuration are almost equally bound and occur within an energy range of less than 1 MeV. Such phenomenon is called shape coexistence. A first experimental indication for shape coexistence comes from the observation of low-lying excited 0+ states. An inversion of the ground state deformation from prolate in 78Kr to oblate in 72Kr with strong mixing of the configurations in 74Kr and 76Kr was proposed based on the systematic of isotopic chain. The direct measurement of the deformation of these nuclei is the essential stage to confirm these assumptions. Coulomb excitation experiments are sensitive to the quadrupole moment. Coulomb excitation experiments of radioactive 74Kr and 76Kr beam were performed at GANIL using the SPIRAL facility and the EXOGAM spectrometer. The analysis of these experiments resulted in a complete description of the transition strength and quadrupole moments of the low-lying states. They establish the prolate character of the ground state and an oblate excited state according to the scenario of shape coexistence. A complementary lifetime measurement of excited states using a “plunger” device was performed to. Transition strength in neighboring nuclei were measured using the technique of intermediate energy Coulomb excitation with fast fragmentation beams separated in with the LISE spectrometer at GANIL. All results are compared to theoretical calculations based on Skyrme and Gogny effective interaction.
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https://tel.archives-ouvertes.fr/tel-00084704
Contributor : Emmanuel Clement <>
Submitted on : Monday, July 10, 2006 - 11:41:10 AM
Last modification on : Thursday, November 5, 2020 - 2:21:28 PM
Long-term archiving on: : Monday, April 5, 2010 - 9:50:36 PM

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Emmanuel Clément. Etude de la coexistence de formes dans les isotopes légers du krypton et du sélénium par excitation Coulombienne de faisceaux radioactifs. Physique Nucléaire Théorique [nucl-th]. Université Paris Sud - Paris XI, 2006. Français. ⟨tel-00084704⟩

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