新核素^(238)Th的鉴别

Identification of New Isotope ^(238)Th

利用６０ＭｅＶ／ｕ的(１８)Ｏ离子束轰击天然铀靶，通过多核子转移反应生成重丰中子新核素(２３８)Ｔｈ．观测到了(２３８)Ｔｈ的子体(２３８)Ｐａγ活性的生长、衰变行为，鉴别了(２３８)Ｔｈ的存在，并测得它的半衰期为（９．４±２．０）ｍｉｎ．同时，发现了一条能量为（８９．０±０．３）ｋｅＶ、半衰期为（８．９±１．５）ｍｉｎ的新γ射线，指定为(２３８)Ｔｈ的衰变γ射线．

Unreported heavy neutron-rich nuclide 238 Th has been produced via amultinucleon transfer reaction by 60MeV/u 18O ions bombardment of natural uranium. Thorium was radiochemically separated from the mixture of uranium and reactionproducts. 238Pa as a daughter nucleus of 238Th has been identified according to thegrowth and decay of 238Pa y rays which has been observed. The half-life of 238Thwas determined to be (9.4 ± 2.0) min. At the same time, a new ray of (89.0± 0.3)keV with min was found in the spectrum gated with the Ka, X rayof Pa and assigned to 238Th decay based on the measurementS of its transition energyand the half-life.