2NCorr Photon flux estimate

A lower bound for the photon flux on the targets can be estimated from the data of a D2O target. The measured neutron rate from D2O depends on the following factors: (G,n) cross-section as a function of energy, the energy distribution of the brem photons, target geometry, detector efficiency, and photon flux. The (G,n) cross-sections are know, the brem energy distribution can be taken from an MCNP simulation. This leaves photon flux and detector efficiency as the only unknown variables. By setting detector efficient to 100%, and considering only geometric effect (solid angle), a lower bound can be set on the photon flux.

neutron rate [math]= N_{\gamma}*\int_0^{10.5}\! \epsilon(E)*P(n_0|E)*P(E)\,dE[/math]