Development of High-Efficiency Recoil Separators and Study of Rare Events in Nuclear Decay and Reaction

本项目的目的是研制一种适合于研究远离稳定线的未知短寿命核素的在线同位素分离器（ISOL），并在实际实验中证明其实用性。在此基础上进行了以下研究，发现了离子导向ISOL（IGISOL）的新效应，大大改进了惯性导航系统中现有的分离器，实现了世界上独一无二的新型ISOL。利用这些新发展的技术，我们成功地进行了几次寻找未知重同位素和核衰变与反应中罕见现象的实验。IGISOL中等离子体效应的发现(ii)充气反冲同位素分离器的改进(iii)为了避免重离子反应中严重的等离子体效应，采用GARIS作为IGISOL的注入器，进行了一个串联反冲分离器的试验和建造.稀有现象的研究（i）某些缺中子锕系元素同位素的鉴定及其衰变的精确测量。(ii)首次测量了~ 2 Po和~ 2 Po的同分异构跃迁分支比<211m><212m>。(iii)^ C+^ C反应中俘获射线的测量<12><12>和亚分子体系的研究。

The aim of the present project is to develop an isotope separator on-line (ISOL) suitable for the study of unknown short-lived nuclides far from the stability line and to prove its usufulness in actual experiments. The researches described below have been done in connection with this, resulting in the important discovery of a new effect of an ion-guide based ISOL (IGISOL), great improvement of the existing separators in INS and realization of a new type ISOL unique in the world. By using those newly developed techniques, we have sucessfully performed several experiments on the search for unknown heavy isotopes and rare phenomena in nuclear decays and reactions.1. Development of a Recoil-Type Isotope Separator (i) Discovery of a plasma effect in IGISOL. (ii) Improvement of a gas-filled recoil isotope separator (GARIS). (iii) Test and Construction of a tandem-type recoil separator, in which GARIS is used as an injector to IGISOL in order to avoid serious plasma effect in heavy-ion reactions.2. Study of Rare Phenomena (i) Identification of some neutron-deficient actinide isotopes and precise measurements on their decays. (ii) The first measurement on branching ratios of isomeric transitions in ^<211m>Po and ^<212m>Po. (iii) Measurements of capture -rays in the ^<12>C+^<12>C reaction and study of submolecular systems.