Using the Schwinger variational functional for the solution of inverse transport problems

Conference · Tue Jan 01 04:00:00 EST 2002

DOI:https://doi.org/10.13182/NSE02-96· OSTI ID:976392

Favorite, J A ^[1]

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1. Jeffrey A.

A new iterative inverse method for gama-ray transport problems is presented. The method, based on a novel application of the Schwinger variational functional, is developed as a perturbation problem in which the current model (in the iterative process) is considered the initial, unperturbed system, and the actual model is considered the perturbed system. The new method requires the solution of a set of uncoupled one-group forward and adjoint transport equations in each iteration. Four inverse problems are considered: determination of (1) interface locations in a multilayer sourcehhield system; (2) the isotopic composition of an unknown source (including inert elements); (3) interface locations and the source composition simultaneously; and (4) the composition of an unknown layer in the shield. Only the first two problems were actually solved in numerical one-dimensional (spherical) test cases. The method worked well for the unknown interface location problem and extremely well for the unknown source composition problem. Convergence of the method was heavily dependent on the initial guess.

• Research Organization: Los Alamos National Laboratory
• Sponsoring Organization: DOE
• OSTI ID: 976392
• Report Number(s): LA-UR-02-6514
• Country of Publication: United States
• Language: English

Related Subjects

97 MATHEMATICS AND COMPUTING
CONVERGENCE
FUNCTIONALS
GAMMA TRANSPORT THEORY
TRANSPORT