113,115,117和118号超重元素的推荐命名和超重原子核的研究

• 作者: 罗亦孝
• 来源期刊: 科学通报
• 年，卷（期）: 2016,（21）
• 所属期刊栏目: 观点
• 页码范围: 2326-2330
• 页数: 5页
• 语种: 中文
• DOI: 10.1360/N972016-00710

摘要

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≥1 12.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 α 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.