(source: https://www.rsc.org/periodic-table/element/98/californium)

Californium 252 is a powerful neutron emitter. It is used as a neutron source either as the metal (Californium-252 Neutron Source And Method Of Making Same (1972)), or alloy (Californium-Palladium Metal Neutron Source Material (1974)).

Californium 252 neutron sources can be used:

References:

All patent information has been obtained from Espacenet (European Patent Office).