Frédéric Joliot-Curie Created 2026-10-24 Updated 2026-11-05
Frédéric Joliot and Irène Joliot-Curie demonstrated that irradiation can create material that still exhibits radioactivity after the irradiating source is removed. In their 1934 report, aluminium exposed to a polonium source continued to emit Positrons afterward, with an exponentially decreasing count rate. Similar behavior in other light elements showed that irradiation had produced unstable nuclear species. Measuring the subsequent radioactive decay separated this persistent activity from radiation produced only during the incoming-particle collisions.[ref]