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DTRA’s advancements in nuclear and radiological detection
A new, more complex nuclear age has begun. Echoing the tensions of the Cold War amid rapidly evolving nuclear and radiological threats, preparedness in the modern age is a contest of scientific innovation. The Research and Development Directorate (RD) at the Defense Threat Reduction Agency (DTRA) is charged with winning this contest.
Sara A. Pozzi, Imre Pázsit
Nuclear Science and Engineering | Volume 154 | Number 3 | November 2006 | Pages 367-373
Technical Paper | doi.org/10.13182/NSE06-A2639
Articles are hosted by Taylor and Francis Online.
In a recent paper, a simple analytical model to describe the statistics of the number of scattering collisions undergone by fast neutrons as they slow down until they are absorbed was presented. In that study, it was assumed that the moderator was infinite and homogeneous and accounted for scattering and absorption by a single nuclear species. In the present paper, that methodology is extended to the more realistic case of neutron slowing down in a homogeneous mixture. The formulas are derived and evaluated numerically, and the results are found to be in very good agreement with corresponding Monte Carlo simulations. The average value of the number of collisions that a neutron undergoes before being captured is computed. The results for a capture-gated detector composed of hydrogen, carbon, and boron are discussed.