[1] The concept is credited to Italian scientist Carlo Rubbia,[2] a Nobel Prize particle physicist and former director of Europe's CERN international nuclear physics lab.
He published a proposal for a power reactor (nicknamed "Rubbiatron") based on a proton cyclotron accelerator with a beam energy of 800 MeV to 1 GeV, and a target with thorium as fuel and lead as a coolant.
Rubbia's scheme also borrows from ideas developed by a group led by nuclear physicist Charles Bowman of the Los Alamos National Laboratory[3] The energy amplifier first uses a particle accelerator (e.g. linac, synchrotron, cyclotron or FFAG) to produce a beam of high-energy (relativistic) protons.
OMEGA project (option making of extra gain from actinides and fission products (オメガ計画)) is being studied as one of methodology of accelerator-driven system (ADS) in Japan.
[7] Richard Garwin and Georges Charpak describe the energy amplifier in detail in their book "Megawatts and Megatons: A Turning Point in the Nuclear Age?"