Identification of the slow E3 transition 136 Cs m → 136 Cs with conversion electrons

Physical Review C (Impact Factor: 3.72). 07/2011; 84:014329. DOI: 10.1103/PhysRevC.84.014329

ABSTRACT We performed at ISOLDE the spectroscopy of the decay of the 8 − isomer in 136 Cs by γ and conversion-electron detection. For the first time the excitation energy of the isomer and the multipolarity of its decay have been measured. The half-life of the isomeric state was remeasured to T 1/2 = 17.5(2) s. This isomer decays via a very slow 518-keV E3 transition to the ground state. In addition to this, a much weaker decay branch via a 413-keV M4 and a subsequent 105-keV E2 transition has been found. Thus we have found a new level at 105 keV with spin 4 + between the isomeric and the ground state. The results are discussed in comparison to shell-model calculations.

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    ABSTRACT: Odd-odd 136Cs nuclei have been produced in the 18O+208Pb and 12C+238U fusion-fission reactions and their γ rays studied with the Euroball array. The high-spin level scheme was built up to ∼4.7 MeV excitation energy and spin I∼16ℏ from the triple γ-ray coincidence data. The configurations of the three structures observed above ∼2 MeV excitation energy are first discussed by analogy with the proton excitations identified in the semimagic 137Cs82 nucleus, which involve the three high-j orbits lying above the Z=50 gap, πg7/2, πd5/2, and πh11/2. This is confirmed by the results of shell-model calculations performed in this work.
    Physical Review C 05/2013; 87(5). · 3.72 Impact Factor
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    ABSTRACT: In the present work recently available experimental data (Astier et al 2012 Phys. Rev. C 85 064316) for the high-spin states of five N = 82 isotones, 136 54Xe, 137 55Cs, 138 56Ba, 139 57La and 140 58Ce have been interpreted with shell model calculations. The calculations have been performed in the 50–82 valence shell composed of 1g7/2, 2d5/2, 1h11/2, 3s1/2 and 2d3/2 orbitals. We have compared our results with the available experimental data for excitation energies including high-spin states, occupancy numbers and transition probabilities. As expected the structure of these isotones are due to proton excitations across the Z = 50 shell. The structure of the positive-parity states are mainly from (πg7/2πd5/2)n and (πg7/2πd5/2)n − 2(πh11/2)2 configurations, while the negative-parity states have a (πg7/2πd5/2)n(πh11/2)1 configuration. Additionally, for the 136 54Xe, 137 55Cs and 138 56Ba isotones the excitation of the neutrons across the N = 82 gap is important.
    Journal of Physics G Nuclear and Particle Physics 01/2013; 40(3):035106. · 5.33 Impact Factor


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