Gamma-Coincidence Modeling with MCNPX

Tertiary neutrons produced in self-sustaining Inertial Confinement Fusion reactions can activate a carbon target through n + $^{12}$C $\to \quad ^{11}$C + $\beta ^{+}$. The subsequent positron-electron annihilations lead to .511-MeV coincidence gammas, and therefore the tertiary neutron yield can be determined by a gamma-coincidence detection experiment. Monte Carlo N-Particle eXtended transport code (MCNPX) is used to model the $^{12}$C experiment, and through a comparison with real data, the geometry for the detector system can be determined. MCNPX is also used to model the non-uniform neutron activation of the $^{12}$C. Results will be presented.