The generation of condensation nuclei by ionising radiation

Summary The production of condensation nuclei by the irradiation of filtered nuclei-free air by X-rays, alpha particles and beta particles is described. It is found that nuclei are created in large numbers by such irradiation and that there appears to be a threshold radiation dose at which the nucleus concentration is increased by a factor of more than a hundred.The effect of varying sulphur dioxide content of the irradiated air has been investigated and for concentrations of between one and ten milligrams per cubic metre of air there is some proportionality between the sulphur dioxide content of the air and the nucleus concentration produced by a given radiation dose.It is shown, however, that sulphur dioxide cannot be exclusively responsible for the generation of condensation nuclei by irradiation of filtered air and other possible agents and mechanisms are suggested.