Observation of laser action in CO gas excited only by fission fragments

Abstract

We report the first clear observation of laser action in a medium excited only by fission fragments. CO gas at 77 °K and pressure ≈100 Torr was excited by fission fragments from enriched 235U3O8 foils, which were irradiated with neutrons from a fast−burst reactor. The laser signal was ≳103 times the fluorescence signal, disappeared if the laser output mirror was misaligned, and had a very sharp onset and fall. The measured laser pulse energy was 10 times the maximum possible fluorescence energy.