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, meaning it takes that long for half of a sample to decay. Californium-249 is primarily produced in nuclear reactors and is used in various applications, including neutron sources and scientific research. This isotope emits neutrons, making it valuable in fields like nuclear science and radiography. It can help in detecting metals and analyzing materials. Due to its radioactivity, handling californium-249 requires strict safety protocols to protect against radiation exposure.