2015考研英语阅读现代炼金术_大学英语阅读

2015考研英语阅读现代炼金术

　　This happens at two places-islands of instability, if you like-in the middle of the table. As aresult technetium, element number 43, and promethium, 61, are always radioactive . Further down the table, where nuclei getheavier and elements less familiar, instability happens more and more often. No elementheavier than lead has a stable isotope, and above number 92 lifetimes are so short that these substances are almost non-existent in nature. Such transuranic elements can, however, be made artificially by the fusion of lighter ones. Andthat is precisely what Dr Dullmann intends to do in the case of element 119, by firingtitanium atoms at those of berkelium and hoping some of them merge.

　　这样的不稳定元素岛在周期表中部的两处出现。锝和钷都是放射性的，并且在自然中的存在数量无法侦测。周期表中继续向下看，元素的原子核都变得越来越重，元素也越来越不为人所熟悉，不稳定性更是频繁出现。比铅更重的元素都没有稳定的同位素，在铀之后的元素寿命太短，以致于在自然界中几乎不存在。这些超铀元素可以通过更轻元素的熔合来人工合成，这也是Dullmann博士想对119号元素应用的，将钛原子与锫原子大量熔合，希望其中一些可以合并产生新元素。

　　Making a new element is tricky. The titanium atoms must be travelling fast enough in GSI sparticle accelerator to overcome the repulsion between their protons and those of theberkelium, yet slowly enough to avoid ripping the newly formed atom of element 119 apartbefore it has had time to settle down. With the right mix, though, Dr Dullmann is confidentthat one or two atoms of 119 will be created over the course of the next few months, and willhang around long enough to be detected.