A new 'Implicit correlation' method for cross-correlation sampling in MCNPX-PoliMi
- Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI, 48109-2104 (United States)
Monte Carlo particle transport codes used to accurately model detector response are traditionally run in fully analog mode. Analog simulations of cross-correlation measurements with these codes are extremely time-consuming because the probability of correlated detection is extremely small, approximately equal to the product of the probabilities of a single detection in each detector. The new 'implicit correlation' method described here increases the number of correlation event scores thereby reducing variance and required computation times. The cost of the implicit correlation method is comparable to the cost of simulating single event detection for the lowest absolute detector efficiency in the problem. This method is especially useful in the nuclear non-proliferation and safeguards fields for simulating correlation measurements of shielded special nuclear material. The new method was implemented in MCNPX-PoliMi for neutron-neutron cross-correlations with a Cf-252 spontaneous fission source measured by two detectors of variable stand-offs. The method demonstrated good agreement with analog simulation results for multiple measurement geometries. Small differences between non-analog and analog cross-correlation distributions are attributed to known features of the specific problem simulated that will not be present in practical applications. (authors)
- Research Organization:
- American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 22212852
- Resource Relation:
- Conference: M and C 2013: 2013 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, Sun Valley, ID (United States), 5-9 May 2013; Other Information: Country of input: France; 5 refs.; Related Information: In: Proceedings of the 2013 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering - M and C 2013| 3016 p.
- Country of Publication:
- United States
- Language:
- English
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