Fast Neutron Spectrum Unfolding for Nuclear Nonproliferation and Safeguards Applications

We present new neutron spectrum unfolding results obtained from measurements with Cf-252 and plutonium-oxide sources. A neutron spectrum unfolding technique based on a modification of the least-squares method was applied. The main innovation is the use of a Krylov subspace iteration method to solve the least-squares normal equations. This method performs better on ill-conditioned systems of linear equations as compared with standard direct-solution methods. The precise knowledge of the neutron energy spectrum provides information not only about the presence or absence of fissile material, but also about the characteristics of the material. The proposed technique performs well in the unfolding of measured neutron pulse-height distributions from a Cf-252 neutron source and from plutonium-oxide samples, and could be implemented in a portable neutron spectroscopy system for nuclear nonproliferation and safeguard applications.

POZZI Sara;  XU Yunlin;  ZAK Thomas;  CLARKE Shaun D.;  BOURNE Mark;  FLASKA M.;  DOWNAR Thomas;  PEERANI Paolo;  PROTOPOPESCU Vladimir; 

2010-12-22

SOC ITALIANA FISICA

JRC55221

0393-697X,   

https://publications.jrc.ec.europa.eu/repository/handle/JRC55221,