A RESPONSE-MATRIX METHOD FOR THE CALCULATION OF NEUTRON PULSE HEIGHT DISTRIBUTIONS IN MCNP

Year
2010
Author(s)
S. A. Pozzi - Department of Nuclear Engineering & Radiological Sciences
S.D. Clarke - Department of Nuclear Engineering & Radiological Sciences
S. Prasad - Department of Nuclear Engineering and Radiological Sciences
E. W. Larsen - Department of Nuclear Engineering and Radiological Sciences
Abstract
The Response-Matrix Method for the calculation of neutron pulse height distribution (Response- Matrix PHD) is applied in order to compute these distributions efficiently by reducing computation time and minimizing variance. In this paper the PHD calculations and their associated uncertainty are compared for lead-shielded and polyethylene-shielded 252Cf source setups. These comparisons are made for three cases: Response-Matrix PHD, Response-Matrix PHD Source Biased, and fully analog MCNP-PoliMi PHD. It is found that the Response-Matrix PHD greatly improves the uncertainty when compared to the fully analog case. The Response- Matrix PHD Source Biased utilizes the source biasing method which is the most applicable given the source energy spectrum of the 252Cf. The Response-Matrix PHD Source Biased improves the uncertainty in the pulse height distributions more efficiently than both the other methods.