title: An iterative method for calculating gamma-ray build-up factors in multi-layer shields.
abstract: Point kernel codes that simulate gamma-ray transport often use build-up factors to take scattered photons into account. This study introduces a new method, for computing multi-layer shield build-up factors. This method, based on an empirical formula for calculating double-layer shield build-up factors, is iterative. For an N-layer shield, each iteration of the method treats the first and the second layer of the shield. It replaces these layers by a single equivalent layer composed of an appropriate material and, hence, it turns the N-layer shield into an (N - 1)-layer shield. In order to determine the equivalent layer of an appropriate material, a neural network approach is developed: some neural networks trained on a large set of various configurations provide the equivalent material for any double-layer configuration. The method is implemented into MERCURE-6.3 straight-line attenuation code and is validated by comparison between MERCURE-6.3 results and reference data for one-dimensional geometries. Reference data obtained from transport calculations performed using the Sn transport code TWODANT. The comparisons prove the accuracy and sturdiness of the method.
authors.affiliation: CEA/Saclay, DEN/DM2S/SERMA/LEPP, Bat. 470, F-91191 Gif-sur-Yvette, France. christophe.suteau@cea.fr
authors.forename: C
authors.initials: C
authors.lastname: Suteau
authors.forename: M
authors.initials: M
authors.lastname: Chiron
mesh_terms: D000465:Algorithms; D017076:Computer-Aided Design; D003252:Construction Materials / Q000032:analysis*; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods*; D005720:Gamma Rays; D009716:Numerical Analysis, Computer-Assisted; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods; D011874:Radiometry / Q000379:methods*; D012542:Scattering, Radiation; D012984:Software