The origin of <i>p</i>-isotopes and their isotopic anomalies

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  • MAKISHIMA Akio
    Institute for Study of the Earth's Interior, Okayama University
  • Lu Qi
    Laboratory of REE Microanalysis, Department of Chemistry, Faculty of Science, The University of Tokyo: (Present address) Department of Chemistry, The University of Electro-Communications
  • MASUDA Akimasa
    Laboratory of REE Microanalysis, Department of Chemistry, Faculty of Science, The University of Tokyo: (Present address) Department of Chemistry, The University of Electro-Communications

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Other Title
  • <i>p</i>-核種の生成とその同位体比異常
  • p-核種の生成とその同位体比異常
  • p-カクシュ ノ セイセイ ト ソノ ドウイタイヒ イジョウ

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Abstract

The origin of p-isotopes (proton rich isotopes) and their isotopic anomalies are reviewed in this article. The p-isotopes (84Sr,124Xe, 130Ba, 144Sm, 196Hg, etc.) are heavy isotopes (A≧74) which cannot be synthesized by s-process or r-process. The p-isotopes are considered to be produced by the transmutation of heavy elements into lighter p-isotopes via a series of (γ, n), (γ, p) and (γ, α) reactions in supernovae. We can constrain the site and the condition of nucleosynthesis in supernovae from abundances of the p-isotopes. The isotopic anomalies of the p-isotopes of Xe, Cd and Sn are found in acid residues of the Allende carbonaceous chondrite. The anomalies of 84Sr and 144Sm are also found in the Allende FUN inclusions. They are considered to be presolar origin. The anomalies of 196Hg are found, however, their origin still remains enigmatic. The anomaly of Mo isotopic abundances is found in the Sikhote-Alin iron meteorite. The anomaly can be explained by (γ, n) reaction chains of Mo. The further study of the Mo anomaly will give us interesting informations not only about the p-process, but also about the r-process effect on 93Nb, the double β--decay of 96Zr, and the (γ, n) reaction chain of 99Tc.

Journal

  • Chikyukagaku

    Chikyukagaku 26 (1), 41-50, 1992

    The Geochemical Society of Japan

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