This element, Pu, was first detected in a cyclotron at Berkely in 1940
[DOC] [TLE] 1940's - Berkeley Lab History [PAR] The 184-inch cyclotron operated for the first time on Nov. ... leading to his 
discovery of radioactive carbon-14 on February 27, 1940  two days before ... 
used the 60-inch cyclotron to bombard uranium with neutrons, creating element 
93, ... A year later Seaborg named it plutonium; he intended the symbol Pu as a 
comment... [DOC] [TLE] Plutonium | Atomic Heritage Foundation [PAR] Plutonium's discovery in 1941 created unique opportunities and challenges for 
scientists.