Evaluation of prompt fission gamma rays for use in simulating nuclear safeguard measurements

Nondestructive assay methods that rely on measurement of correlated gamma r ays from fission have been proposed as a means to determine the mass of fis sile materials. Sensitivity studies for such measurements will require know ledge of the multiplicity of prompt gamma rays from fission; however, a ver y limited number of multiplicity distributions have been measured. A method is proposed to estimate the average number of gamma rays from any fission process by using the correlation of neutron and gamma emission in fission. Using this method, models for the total prompt gamma ray energy from fissio n adequately reproduce the measured value for thermal neutron induced fissi on of U-233. Likewise, the average energy of prompt gamma rays from fission has been adequately estimated using a simple linear model. Additionally, a method to estimate the multiplicity distribution of prompt gamma rays from fission is proposed based on a measured distribution for Cf-252. These met hods are only approximate at best and should only be used for sensitivity s tudies. Measurements of the multiplicity distribution of prompt gamma rays from fission should be performed to determine the adequacy of the models pr oposed in this article. Published by Elsevier Science Ltd.