希土類核の選択的同位体分離法の研究と未知核種探索への応用

概要

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In order to search for unknown lanthanide isotopes using on-line isotope separation, the selective mass separation of lanthanides was studied on the basis of monoxide ion formation in a thermal ion-source. For this purpose, an integrated target-ion source and a gas-jet coupled ion source was developed. With these ion sources, off-line and on-line experiments were performed. The off-line experiments were carried out in order to understand the ionization behavior of the elements from Ba to Sm in the ion source, starting with their oxide reagents. The observed MO^+/M^+ ratio was highest for La and Ce, and decreased with atomic number and temperature. In on-line experiments, La isotopes produced in heavy-ion fusion-evaporation reactions were mass-separated as La^<16>O^+, being well separated from the Cs and Ba isobars. Using the gas-jet coupled thermal ion source, Gd and Tb isotopes produced in the proton-induced fission of ^<238>U were observed as m onoxide ions, being well separated from other molecular species, when a small amount of oxygen gas was injected into the gas-jet stream in order to enhance the chemical reaction of M^+O → MO in the ion-source. Using this method, new isotopes of ^<121>La, ^<125>Pr, ^<127>Pr, ^<165>Gd and ^<166>Tb were identified.
社団法人日本分析化学会の論文
1998-07-05