Study on double beta-decays of <^(128)Te> and <^(130)Te> .

1986 Fiscal Year Final Research Report Summary

• Project/Area Number: 60460012
• Research Category: Grant-in-Aid for General Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: 核・宇宙線・素粒子
• Research Institution: Yamagata University
• Principal Investigator: TAKAOKA Nobuo Faculty of Science, Yamagata University, 理学部, 教授 (40028171)
• Co-Investigator(Kenkyū-buntansha): NOMA Gensaku Faculty of Science, Yamagata University, 理学部, 講師 (50007168)
• Project Period (FY): 1985 – 1986
• Keywords: Double beta-decay / Half-life

Research Abstract

1) From a tellurium mineral collected at the Suwa mine, Japan, a half-life for double beta-decay of <^(130)Te> has been determined to be (8.5 <+!-> 1.2) x <10^(20)> years. This result is in good agreement with the half-life reported by Takaoka and Ogata (1966) and that given by the Missouri group (Manuel, 1986), and different from the half-life given by the Heidelberg group (Kirsten et al., 1986).
2) For a tellurium mineral (petzite, <Ag_3> AuTe) collected at the Cash mine, Co. USA, we have determined the amount of <^(130)Xe> produced by double beta-decay of <^(130)Te> . The half-life is (8.6 <+!-> 2.3) x <10^(20)> years with assumptions of a mineral age of Laramide (63 <+!-> 17 Ma) and of a tellurium content of 20% that was estimated from the chemical formula of petzite.
3) K-Ar dating gives extra-ordinarily old ages for tellurium-bearing calcitequartz veins collected at the Suwa and Oya mines, Japan. The apparent ages are three to eight times older than the ages which have been considered to be correct from geological and geochronological evidence. This indicates that minerals in these veins contain excess Ar, and hence that the K-Ar dating of low potassium minerals such as calcite and tellurium minerals may give incorrect, possibly older ages for the formation of tellurium ores.