Decay of a {pi}h{sub 11/2} x {nu}h{sub 11/2} microsecond isomer in {sub 61}{sup 136}Pm{sub 75}

Journal Article · Mon Sep 15 04:00:00 EDT 2008 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.78.034304· OSTI ID:21192186

Rigby, S V; Cullen, D M; Mason, P J. R.; Scholes, D T ^[1]; Scholey, C; Rahkila, P; Eeckhaudt, S; Grahn, T; Greenlees, P; Jones, P M; Julin, R; Juutinen, S; Kettunen, H; Leino, M; Leppaenen, A -P; Nieminen, P; Nyman, M; Pakarinen, J; Uusitalo, J ^[2]

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1. Schuster Laboratory, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom)
2. Department of Physics, University of Jyvaeskylae, Jyvaeskylae, FIN-40014 (Finland)

An experiment has been performed to populate several extremely neutron-deficient nuclei around the mass-140 region of the nuclear chart, using a beam of {sup 54}Fe on a {sup 92}Mo target at an energy of 315 MeV. Analysis of these data using recoil-isomer tagging has established that the yrast {pi}h{sub 11/2} x {nu}h{sub 11/2},J{sup {pi}}=(8{sup +}), bandhead state in {sup 136}Pm is isomeric with a half-life of 1.5(1) {mu}s. This isomeric state decays via a 43-keV, probable-E1 transition to a J{sup {pi}}=(7{sup -}) state. Consideration of the theoretical Nilsson orbitals near the Fermi surface suggests that the J{sup {pi}}=(8{sup +}) state has a {nu}h{sub 11/2}[505](11/2){sup -} x {pi}h{sub 11/2}[532](5/2){sup -} configuration, which decays to the J{sup {pi}}=(7{sup -}) state with a {nu}h{sub 11/2}[505](11/2){sup -} x {pi}d{sub 5/2}[411](3/2){sup +} configuration. Differences in the shape-driving effects for these two configurations is reasoned to be responsible for the long half-life of the J{sup {pi}}=(8{sup +}) isomeric state. The non-observation of other {gamma} rays in prompt or delayed coincidence with the 43-keV transition suggests that this transition may feed another, longer lived isomeric state with a half-life of the order of milliseconds or greater. However, the present experiment was not sensitive to the decay of this new J{sup {pi}}=(7{sup -}) state by internal conversion or even {beta} decay.

• OSTI ID: 21192186
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 3 Vol. 78; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BEAMS
BETA DECAY
CONFIGURATION
E1-TRANSITIONS
FERMI LEVEL
GAMMA RADIATION
HALF-LIFE
INTERNAL CONVERSION
IRON 54
ISOMERS
KEV RANGE
MASS
MEV RANGE 100-1000
MOLYBDENUM 92 TARGET
NEUTRON-DEFICIENT ISOTOPES
PROMETHIUM 136
RECOILS