Samuel T. Cohen, an American physicist who worked on building the atomic bomb, said in his autobiography that red mercury is manufactured by "mixing special nuclear materials in very small amounts into the ordinary compound and then inserting the mixture into a nuclear reactor or bombarding it with a particle-accelerator beam." When detonated, this mixture allegedly becomes "extremely hot, which allows pressures and temperatures to be built up that are capable of igniting the heavy hydrogen and producing a pure-fusion mini neutron bomb."