Gamma Factory: A novel research programme for CERN

\abstract{{\bf "New directions in science are launched by new tools more often than by new concepts."} At the current stage of accelerator-technology-based research, where conventional methods have reached the saturation limits of particle beam energy and intensity, the Gamma Factory (GF) project proposes breakthroughs in beam intensity (up to seven orders of magnitude), quality (low emittance, polarization with CP tagging, and flavor tagging), and precision control for several types of particle beams. The Gamma Factory can produce primary (ions), secondary (photons), and tertiary (polarized positrons, muons, neutrinos, neutrons, and radioactive ions) beams with unprecedented wall-plug-to-beam power efficiency—outperforming existing schemes by several orders of magnitude. GF aims to extend CERN’s scientific program across multiple domains of research (particle, nuclear, atomic, astrophysics, accelerator, and applied physics) with reasonable investment costs by reusing CERN’s existing accelerator infrastructure. Its environmental impact is expected to be minimal, as the plug power required for its research program could be generated by a novel GF-beam-driven, waste-transmuting, subcritical nuclear reactor. New GF beam-cooling techniques and innovative methods for producing polarized muon beams could improve the precision of Standard Model parameter measurements and enable the first observation of exclusive production of Higgs bosons in photon–photon collisions. If implemented at CERN, the GF experimental program could follow the HL-LHC phase and be carried out during the preparation period for the next large-scale, energy-frontier accelerator. This contribution presents the ongoing GF R\&D studies, including the recent world record in laser–photon beam power, the status of the GF proof-of-principle SPS experiment, and selected highlights from the latest quantitative analyses of GF research applications.