A technician at Lawrence Livermore National Laboratory, California, manoeuvres a cylindrical casket of fruit above an accelerator pool used for the study of irradiation of foodstuffs. Submerged in the pool is a 2 million electron volt (2 MeV) accelerator, a source of the X-rays that are used to preserve perishable foodstuffs. X-rays are produced when the high-energy beam of electrons strikes a dense, tungsten target. The irradiation operation is carried out under water, which acts to protect personnel from exposure to radiation.