Shapes of the neutron-rich ${^{88-94}Kr}$ nuclei

T. Rząca-Urban; W. Urban; A. Kaczor; J.L. Durell; M.J. Leddy; M.A. Jones; W.R. Phillips; A.G. Smith; B.J. Varley; I. Ahmad; L.R. Morss; M. Bentaleb; E. Lubkiewicz; N. Schulz

doi:doi:10.1007/s100500070033

EPJ

Shapes of the neutron-rich ^88-94Kr nuclei

T. Rzaca-Urban¹ - W. Urban¹ - A. Kaczor¹ - J.L. Durell² - M.J. Leddy² - M.A. Jones² - W.R. Phillips² - A.G. Smith² - B.J. Varley² - I. Ahmad³ - L.R. Morss³ - M. Bentaleb⁴ - E. Lubkiewicz⁴ - N. Schulz⁴

¹ Institue of Experimental Physics, Warsaw University, ul.Hoza 69, 00-681 Warszawa, Poland
² Schuster Laboratory, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.
³ Argonne National Laboratory, Argonne, IL 60439, U.S.A.
⁴ Institut de Recherches Subatomiques UMR7500, CNRS-IN2P3 et Université Louis Pasteur, 67037 Strasbourg, France
urban@fuw.edu.pl

Received: 18 September 2000
Communicated by D. Schwalm

Abstract
Neutron-rich, $\ensuremath{\mathsf{^{88\mbox{-}94}Kr}}$ nuclei, populated in spontaneous fission of ²⁴⁸Cm, have been studied with EUROGAM 2, by measuring prompt $\gamma$ -rays. Many new excited states in even-even Kr isotopes have been identified. For the first time spins and parities were determined experimentally in these nuclei. Our results indicate that the quadrupole deformation of Kr isotopes will appear only above N=58, as observed in Sr and Zr nuclei. The newly found 3^- level at 1506.4 keV in ⁹⁰Kr suggests the exsistence of a new region of increased octupole correlations, probably associated with the ${\nu (d_{5/2} h_{11/2})}$ pair of $\Delta l=\Delta j=3$ orbitals.

PACS
21.10.-k Properties of nuclei; nuclear energy levels - 23.20.Lv Gamma transitions and level energies - 25.85.Ca Spontaneous fission - 27.60.+j $90 \leq A \leq 149$

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Shapes of the neutron-rich 88-94Kr nuclei

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Shapes of the neutron-rich ^88-94Kr nuclei