新重丰中子同位素^(238)Th(英文)  

A New Heavy Neutron-rich Isotope ^(238)Th

作　　者：徐岩冰[1] 袁双贵[1] 杨维凡[1] 何建军[1] 李宗伟[1] 马桃桃[1] 熊兵[1] 秦芝[1] 牟万统[1] 甘再国[1] 石立军[1] 郭天瑞[1] 陈展图[1] 郭俊盛[1] 

机构地区：[1]中国科学院近代物理研究所,兰州730000

出　　处：《高能物理与核物理》1999年第1期93-95,共3页High Energy Physics and Nuclear Physics

基　　金：国家自然科学基金!19775055;中国科学院重大项目

摘　　要：利用兰州重离子加速器（HIRFL）所提供的60MeV／u的18O离子束照射天然铀靶，通过多核子转移反应生成238Th．由快速放射化学分离技术从铀及其反应产物的混合物中分离出钍．使用2台高纯锗（HPGe）探测器对样品的γ（X）活性进行测量，观测到了238Th的β-衰变子体238Pa的635．0keV和1060．5keV2条γ射线峰的增长、衰变行为．利用分析递次衰变的计算机程序对其后一条进行了拟合，得到母、子体半衰期分别为（9．4±2．0）min和（2．1±0．4）min，二者分别与预言值和文献值相符．另外，在由238Pa的X射线开门的γ谱中，发现一条能量为89．0keV的新γ射线，经计算，其半衰期为（8．9±1．5）min，由跃迁能量和半衰期的关系认定该射线来源于238Th的β-衰变．从而证明本实验合成和鉴别了重丰中子新核素238Th，并测定它的半衰期为（9．4±2．0）min．A new nuclide 238Th has been produced via multinucleon transfer reaction induced by 60MeV/u 18O ion irradiation of natural uranium. The thorium was radiochemically separated from the mixture of uranium and its reaction products. The activity of thorium was measured by using a HPGe detector and a planar HPGe detector. The 238Th has been identified for the first time by measuring the growth and decay of the γ-rays from its daughter 238Pa. The half-life of 238Th was determined to be (9.4 ± 2.0)min. In addition,a new (89.0 ± 0.3)keV γ-ray with T1/2 = (8.9 ± 1.5)min was observed and assigned to 238 Th decay based on the measurement of transition energy and half life.

关 键 词：新核素 多核子转移反应 重丰中子同位素 Th238 

分 类 号：O571.34[理学—粒子物理与原子核物理]