Nuclear weapons use a neutron initiator, a neutron source capable of producing a burst of neutrons in order to "kick-start" the nuclear chain reaction at the optimal moment. These worked by mixing polonium-210 and beryllium. Polonium-210 is an alpha particle emitter with a half-life of 138 days. Alpha particles from the polonium caused the beryllium to emit neutrons. The Kitten trials were experiments conducted as part of the development of the neutron initiators. Five tests were conducted at the K site at Emu Field, about from the Operation Totem test site on 26 and 30 September and 6, 14 and 17 October 1953. These experiments dispersed about of beryllium and of polonium-210 into the surrounding area. Most of the contamination was within a radius, with some debris being thrown up to away. All contamination was within the restricted area.