Californium-249 is a radioactive isotope of the element californium, which is a synthetic element first discovered in 1950. It has a half-life of about 351 years and is produced in nuclear reactors through the bombardment of berkelium with neutrons. Californium-249 is primarily used in scientific research and as a neutron source in various applications. This isotope emits neutrons, making it valuable in fields such as nuclear medicine, radiography, and nuclear reactors. Its ability to produce neutrons allows it to be used in detecting and analyzing materials, as well as in certain types of cancer treatment.