History of chemistry element among the fractions that resulted. Working with the mineral pitchblende, the pair discovered a new radioactive element in 1898. They named the element polonium, after Marie's native country of Poland. On December 21, 1898, the Curies detected the presence of another radioactive material in the pitchblende. They presented this finding to the French Academy of Sciences on December 26, proposing that the new element be called radium. The Curies then went to work isolating polonium and radium from naturally occurring compounds to prove that they were new elements. In 1902, the Curies announced that they had produced a decigram
Modulated neutron initiator particle bombardment, the beryllium atoms emit neutrons at a rate of about 1 neutron each 5–10 nanoseconds (See Beryllium#Nuclear properties). These neutrons trigger the chain reaction in the compressed supercritical plutonium. Placing the polonium layer between two large masses of beryllium ensures contact of the metals even if the shock wave turbulence performs poorly. The 50 curies of polonium generated about 0.1 watts of decay heat, noticeably warming the small sphere. The grooves in the inner surface of the shell shaped the shock wave into jets by the Munroe effect, similar to a shaped charge, for fast and thorough mixing