Efficient and accurate computation of 0th angular moment of the Doppler-broadened elastic scattering kernel in the resonance domain

We have implemented an accurate and fast calculation of the 0th angular moment of the Doppler-broadened kernel PT(E → E′) for neutron elastic scattering based on a gas model. An exponential cutoff which accounts for the asymptotic behavior of the error function helps limit the range of integration while eliminating difference effects. This allows for calculating a kernel library for 238U over a very fine energy grid covering the resonance range in only a few hours in a laptop. We give an example showing the impact of 238U elastic upscattering on the values of self shielded cross sections.