113,115,117和118号超重元素的推荐命名和超重原子核的研究  

The recommended naming for the 113, 115, 117 and 118 elements and the studies of superheavy nuclei

作　　者：罗亦孝 

机构地区：[1]Department of Physics, Vanderbilt University [2]Nuclear physics Division, Lawrence Berkeley National Laboratory

出　　处：《科学通报》2016年第21期2326-2330,共5页Chinese Science Bulletin

摘　　要：超重元素和原子核的理论和实验研究，是数十年来原子核物理和核化学最重要、最引人注目、竞争最为激烈的前沿之一．新超重元素的发现，已将门捷列夫元素周期表第7行右端存在的空缺填满，并为20世纪60年代提出的超重稳定岛的理论预言提供了实验证据．该理论预言，The paper reports the IUPAC recommendation for naming four new superheavy elements, and comments on the progresses and breakthrough in the studies of superheavy nuclei. IUPAC is naming element 113 as Nihonium （Nh）, element 115 as Moscovium （Mc）, element 117 as Tennessine （Ts）, and element 118 as Oganesson （Og）. The suggested names of the new elements are completely in accordance with IUPAC rules, having recognized the contributions of the related country, state, city and scientist, respectively. The seventh row of the Periodic Table of the Elements has now been completed, with the element 118 being the heaviest element synthesized, identified and recognized so far. Since the passed sixties theories predicted an island of stability with long half-lives at or near N= 184 and z〉112. The discoveries of the new superheavy elements were achieved based on the breakthrough in experimental efforts. In stead of cold fusion used for elements 107-113, the production cross sections for which were decreasing with increasing atomic number and down by about eight orders of magnitudes for element 113, hot fusion with 48Ca beams bombarding neutron-rich actinides targets was employed to produce elements 114-118. Hot fusion was also used for the production of the element 113. Well designed separations and detections methods and facilities were employed to separate the products with very low production rates and to detect the decay chains. Newly developed detection methods extended the range of measurable half-lives to lower limits of-1 μs. The identifications of the superheavy nuclei were based on the detections of the sequential Gt decay and the following spontaneous fission of the final nucleus. The first evidences for the long sought island of stability and new superheavy elements have been regarded as the most important discoveries in nuclear physics in the last 30 years, providing understanding of the behavior of nuclear matter under the extreme stress of the ultra-large electrical forces.

关 键 词：超重原子核 超重元素 实验证据 原子核物理 元素周期表 门捷列夫 核化学 稳定岛 

分 类 号：O571.6[理学—粒子物理与原子核物理]