Radium components: compounds of barium, which gave a brilliant green flame color, and unknown radioactive compounds which gave carmine spectral lines that had never been documented before. The Curies found the radioactive compounds to be very similar to the barium compounds, except that they were more insoluble. This made it possible for the Curies to separate out the radioactive compounds and discover a new element in them. The Curies announced their discovery to the French Academy of Sciences on 26 December 1898. The naming of radium dates to about 1899, from the French word "radium", formed in Modern Latin from "radius"
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