In 1937 Carlo Perrier & Emilio Segre filled in no. 43 on this table, the first entry to be artificially produced
... You see, all the radium that we had, with which we made the 
neutron work,... [DOC] [TLE] The first transition series [PAR] Dec 11, 2015 ... For this reason, the metal is not widely used, being restricted to aircraft ...