Aftereffects following β-decay of181Hf1 |
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| Authors: | H. Jaeger H. T. Su John A. Gardner I-Wei Chen J. C. Haygarth J. A. Sommers R. L. Rasera |
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| Affiliation: | (1) Department of Physics, Oregon State University, 97331-6507 Corvallis, OR, USA;(2) Department of Materials Science and Engineering, University of Michigan, 48109-2136 Ann Arbor, MI, USA;(3) Teledyne Wah Chang Albany, 97321 Albany, OR, USA;(4) Department of Physics, University of Maryland Baltimore County, 21228 Catonsville, MD, USA;(5) Present address: Max-Planck-Institut für Metallforschung, 7000 Stuttgart 80, West Germany |
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| Abstract: | Time differential perturbed angular correlation spectra of181Ta produced by beta decay of181Hf in monoclinic ZrO2 have been measured over a temperature range 10K to 1300K. If times near t=0 are excluded, G2(t) is well fitted by a standard single site model for nuclei subject to an interaction with a static electric field gradient. For high purity samples, the effective anisotropy A2 is equal to its expected value above 200°C but decreases abruptly by approximately a factor of two for lower temperatures. This unusual decrease, which does not occur in natural crystals or in Nb-doped powders, is attributed to an aftereffect of the beta emission that populates with approximately 50% probability an electron trap located about one eV below the conduction band. At low temperatures, this trapped electron causes the Ta nucleus to relax rapidly and contributes to G2(t) only near t=0. At high temperatures or in doped samples the electron escapes quickly enough to have negligible effect on G2(t). Supported in part by USDOE contract DE-FG06-85ER45191 |
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