Einsteinium最初是在1952年第一次氢弹爆炸,常春藤迈克核试验的后果中发现的。 加州大学伯克利分校的Albert Ghiorso和他的团队与Los Alamos和Argonne国家实验室一起检测并合成了Es-252,它具有6.6 MeV能量的特征α衰变。 美国团队开玩笑地将元素99命名为“pandamonium”,因为常春藤迈克测试代号为Project Panda,但他们正式提出的名称是“einsteinium”,元素符号为E. IUPAC批准了这个名称,但是符号为Es。 美国团队与斯德哥尔摩诺贝尔物理研究所的瑞典团队竞争,发现99和100元素并将其命名。 常春藤迈克测试已被分类。 美国团队于1954年公布了结果,测试结果于1955年解密。瑞典团队于1953年和1954年公布了结果。


Einsteinium was first identified in the fallout from the first hydrogen bomb explosion in 1952, the Ivy Mike nuclear test. Albert Ghiorso and his team at the University of California at Berkeley, together with Los Alamos and Argonne National Laboratories, detected and later synthesized Es-252, which exhibits a characteristic alpha decay with an energy of 6.6 MeV. The American team jokingly named element 99 “pandamonium” because the Ivy Mike test had been codenamed Project Panda, but the name they officially proposed was ” einsteinium”, with element symbol E. The IUPAC approved the name but went with the symbol Es. The American team competed with a Swedish team at the Nobel Institute for Physics in Stockholm for credit discovering elements 99 and 100 and naming them. The Ivy Mike test had been classified. The American team published results in 1954, with the test results declassified in 1955. The Swedish team published results in 1953 and 1954.