SPECIAL COLLOQUIUM

Thursday, October 26, 2006

NE Conference Room 4101

"Recent Advances in Monte Carlo Simulations for Nuclear Nonproliferation and Homeland Security Applications"

Presented By

Sara Pozzi
Staff Scientist
Oak Ridge National Laboratory

Accurate simulation of realistic threat scenarios of interest in the areas of nuclear nonproliferation and homeland security is essential for the performance assessment of existing measurement systems, and for the design of new, more advanced ones. Typically, these systems use an external neutron or gamma ray source to induce fission in the nuclear material, and prompt and delayed neutrons and gamma rays from fission are subsequently detected with appropriate radiation detectors. Thus, together with the accurate modeling of the physics of various particle interactions, the correct evaluation of the detector response is crucial for the reliability of the prediction of any measurement system’s performance.
To address this problem, research and development efforts at ORNL and elsewhere have been focused on the development of accurate and robust Monte Carlo codes to model the nuclear material and evaluate the response of various radiation detectors. In this presentation, I will discuss current needs in the area of nuclear security and present recent ORNL advances in developing Monte Carlo-based analysis tools and assessment capabilities. In particular, I will present: (i) our new simulation model of photonuclear physics, (ii) our model of the response of organic scintillator detectors, and (iii) a comparison between simulation results and experimental data acquired at a linear accelerator facility.

References
• S. A. Pozzi, E. Padovani, and M. Marseguerra, “MCNP-PoliMi: A Monte Carlo Code for Correlation Measurements,” Nuclear Instruments and Methods in Physics Research, Section A, 513/3 pp. 550-558, 2003.
• S. A. Pozzi, J. A. Mullens, and J. T. Mihalczo, “Analysis of Neutron and Photon Detection Position for the Calibration of Plastic (BC-420) and Liquid (BC-501) Scintillators,” Nuclear Instruments and Methods in Physics Research, Section A, 524/1-3 pp. 92-101, 2004.
• S. A. Pozzi and I. Pázsit, “Neutron Slowing Down in a Detector with Absorption,” Nuclear Science and Engineering, vol. 154, p. 1-7, 2006.
• S. Clarke, S. A. Pozzi, E. Padovani, and T. J. Downar, “Simulation and Analysis of Correlated Neutron and Gamma-ray Detection from Photofission,” Proceedings of the Institute of Nuclear Materials Management Annual Meeting, July 16-20, 2006, Nashville, TN.

Coffee and Cookies 3:45 PM - Colloquium 4 - 5 PM
4101 Etcheverry Hall