<i>p</i>-核種の生成とその同位体比異常 [in Japanese] The origin of <i>p</i>-isotopes and their isotopic anomalies [in Japanese]
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The origin of <i>p</i>-isotopes (proton rich isotopes) and their isotopic anomalies are reviewed in this article. The p-isotopes (<sup>84</sup>Sr,<sup>124</sup>Xe, <sup>130</sup>Ba, <sup>144</sup>Sm, <sup>196</sup>Hg, etc.) are heavy isotopes (A≧74) which cannot be synthesized by <i>s</i>-process or <i>r</i>-process. The <i>p</i>-isotopes are considered to be produced by the transmutation of heavy elements into lighter <i>p</i>-isotopes via a series of (γ, <i>n</i>), (γ, <i>p</i>) and (γ, α) reactions in supernovae. We can constrain the site and the condition of nucleosynthesis in supernovae from abundances of the <i>p</i>-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 <sup>84</sup>Sr and <sup>144</sup>Sm are also found in the Allende FUN inclusions. They are considered to be presolar origin. The anomalies of <sup>196</sup>Hg 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, <i>n</i>) reaction chains of Mo. The further study of the Mo anomaly will give us interesting informations not only about the <i>p</i>-process, but also about the <i>r</i>-process effect on <sup>93</sup>Nb, the double β<sup>-</sup>-decay of <sup>96</sup>Zr, and the (γ, <i>n</i>) reaction chain of <sup>99</sup>Tc.
Chikyukagaku 26(1), 41-50, 1992
The Geochemical Society of Japan