Near-yrast, medium-spin, excited states of {sup 91}Rb, {sup 93}Rb, and {sup 95}Rb

Journal Article · Sun Aug 15 04:00:00 EDT 2010 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.82.024302· OSTI ID:21420880

Simpson, G S ^[1]; Urban, W ^[2]; Sieja, K ^[3]; Dare, J A; Orlandi, R; Smith, A G; Tsekhanovich, I; Varley, B J; Durell, J L; Smith, J F ^[4]; Jolie, J; Linneman, A ^[5]; Scherillo, A ^[6]; Soldner, T; Faust, H ^[2]; Zlomaniec, A; Rzaca-Urban, T ^[7]; Ahmad, I; Greene, J P ^[8]

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1. LPSC, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, F-38026 Grenoble Cedex (France)
2. Institut Laue-Langevin, 6 rue J. Horowitz, F-38042 Grenoble (France)
3. Institute Pluridisciplinaire Hubert Curien, 23 rue du Loess, 67037 Strasbourg Cedex (France)
4. Department of Physics and Astronomy, University of Manchester, M13 9PL Manchester (United Kingdom)
5. Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicherstr. 77, D-50937 Koeln (Germany)
6. Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom)
7. Faculty of Physics, University of Warsaw, ul. Hoza 69, PL-00-681 Warsaw (Poland)
8. Argonne National Laboratory, Argonne, Illinois 60439 (United States)

The medium-spin structure of the nuclei {sup 93}Rb and {sup 95}Rb is studied following the neutron-induced fission of {sup 235}U at the PF1B neutron guide, using the FIFI spectrometer, and at the Lohengrin mass spectrometer of the Institut Laue-Langevin Grenoble. These nuclei, plus {sup 91}Rb, are also studied following the spontaneous fission of {sup 248}Cm and {sup 252}Cf sources, using the EUROGAM-II and Gammasphere detector arrays, respectively. A high-spin isomeric state, with a half-life of 111(11) ns, is found in {sup 93}Rb at an excitation energy of 4422.4 keV, which most likely corresponds to the fully aligned [{pi}(g{sub 9/2}) x {nu}(g{sub 7/2}h{sub 11/2})]{sub 27/2}{sup -} configuration. An analogous configuration is proposed for the 5297.9-keV level observed in {sup 91}Rb. A new E3 decay branch of the 1133.9-keV isomer in {sup 91}Rb is found, for which the rather low transition rate of B(E3)=3.8(10) W.u. is determined. The energy of the isomeric state of {sup 95}Rb is now proposed to be at 810.6 keV, with a spin of (9/2{sup +}), and its half-life determined to be T{sub 1/2}=94(7) ns. A cascade of prompt transitions is observed on top of the 810.6-keV isomer in {sup 95}Rb. The near-yrast structures of {sup 91}Rb, {sup 93}Rb, and {sup 95}Rb are compared to the results of shell-model calculations, which support the proposed 27/2{sup -} interpretation of states in {sup 91}Rb and {sup 93}Rb. An analogous 27/2{sup -} state is expected to occur in {sup 95}Rb, as a long-lived isomer at 3.24 MeV. No such isomeric decay could be observed in a measurement using the Lohengrin spectrometer, which shows that, if it exists, its population, following the fission of {sup 235}U, is at least four times lower than that of the analogous 27/2{sup -} isomer in {sup 97}Y.

• OSTI ID: 21420880
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 2 Vol. 82; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
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ANGULAR MOMENTUM
BARYON REACTIONS
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALIFORNIUM 252
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NUCLEAR MODELS
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NUCLEI
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RUBIDIUM 91
RUBIDIUM 93
RUBIDIUM 95
RUBIDIUM ISOTOPES
SECONDS LIVING RADIOISOTOPES
SHELL MODELS
SPECTROMETERS
SPIN
SPONTANEOUS FISSION
SPONTANEOUS FISSION RADIOISOTOPES
URANIUM 235
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YEARS LIVING RADIOISOTOPES
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YTTRIUM 97
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