Method for on-line evaluation of materials using prompt gamma ray analysis

A method for evaluating a material specimen, comprising:

• mounting a neutron source adjacent the material specimen;
• mounting a detector adjacent the material specimen;
• bombarding the material specimen with neutrons from the neutron source to create prompt gamma rays within the material specimen, some of the prompt gamma rays being emitted from the material specimen, some of the prompt gamma rays resulting in the formation of positrons within the material specimen by pair production;
• collecting positron annihilation data by detecting with the detector a plurality of emitted annihilation gamma rays resulting from the annihilation of positrons, the detector producing the positron annihilation data;
• storing the positron annihilation data on a data storage system for later retrieval and processing;
• and
• continuing to collect and store positron annihilation data, the continued collected and stored positron annihilation data being indicative of an accumulation of lattice damage over time.