在自然界中寻找超重元素109和110
A SEARCH FOR SUPERHEAVY ELEMENTS IN NATURE
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摘要: <正> 引言 理论计算指出:超越周期表末端存在一个以Z=114,N=184为中心的相当稳定的超重核岛,岛上的一些核素可能有相当长的半衰期。若把超重区(106—116)中各核素的三种衰变方式一起考虑,发现~(294)110是最佳候选者,它具有10~8年的总半寿命。 由于测量源厚度的限制以及为了提高探测灵敏度,测量前必须对样品进行化学浓集。观察与天然核素发射的(能量已知的)α粒子不同的α事件或自发裂变事件,是判断超重核存在的一种很灵敏的方法。Abstract: The results of a search for elements 109 and 110 in nature are reported. No significant activity was observed in the sample by solid track measurements, but an excess a-activity exists in the 4.3-4.6 MeV region as shown by the a-pulse-height spectrum of the nickel anode mud sample. Assuming a half life of 108 years for the superheavy elements concerned, the upper limits of the concentration of elements 109 and 110 are estimated at 10-13 and 10-11 grams per gram of sample respectively.