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Title: Calculation of self–shielding factor for neutron activation experiments using GEANT4 and MCNP

Abstract

The neutron self–shielding factor G as a function of the neutron energy was obtained for 14 pure metallic samples in 1000 isolethargic energy bins from 1·10{sup −5}eV to 2·10{sup 7}eV using Monte Carlo simulations in GEANT4 and MCNP6. The comparison of these two Monte Carlo codes shows small differences in the final self–shielding factor mostly due to the different cross section databases that each program uses.

Authors:
 [1];  [2];  [1];  [1];  [2];  [3]
  1. Comisión Chilena de Energía Nuclear, Nueva Bilbao 12501, Las Condes, Santiago (Chile)
  2. (Chile)
  3. Universidad de Chile, DFI, Facultad de Ciencias Físicas Y Matemáticas, Avenida Blanco Encalada 2008, Santiago (Chile)
Publication Date:
OSTI Identifier:
22608534
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1753; Journal Issue: 1; Conference: Latin American symposium on nuclear physics and applications, Medellin (Colombia), 30 Nov - 4 Dec 2015; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; CROSS SECTIONS; MONTE CARLO METHOD; NEUTRON ACTIVATION ANALYSIS; NEUTRONS; SELF-SHIELDING

Citation Formats

Romero–Barrientos, Jaime, E-mail: jaromero@ing.uchile.cl, Universidad de Chile, DFI, Facultad de Ciencias Físicas Y Matemáticas, Avenida Blanco Encalada 2008, Santiago, Molina, F., Aguilera, Pablo, Universidad de Chile, Depto. de Física, Facultad de Ciencias, Las Palmeras 3425, Ñuñoa, Santiago, and Arellano, H. F. Calculation of self–shielding factor for neutron activation experiments using GEANT4 and MCNP. United States: N. p., 2016. Web. doi:10.1063/1.4955388.
Romero–Barrientos, Jaime, E-mail: jaromero@ing.uchile.cl, Universidad de Chile, DFI, Facultad de Ciencias Físicas Y Matemáticas, Avenida Blanco Encalada 2008, Santiago, Molina, F., Aguilera, Pablo, Universidad de Chile, Depto. de Física, Facultad de Ciencias, Las Palmeras 3425, Ñuñoa, Santiago, & Arellano, H. F. Calculation of self–shielding factor for neutron activation experiments using GEANT4 and MCNP. United States. doi:10.1063/1.4955388.
Romero–Barrientos, Jaime, E-mail: jaromero@ing.uchile.cl, Universidad de Chile, DFI, Facultad de Ciencias Físicas Y Matemáticas, Avenida Blanco Encalada 2008, Santiago, Molina, F., Aguilera, Pablo, Universidad de Chile, Depto. de Física, Facultad de Ciencias, Las Palmeras 3425, Ñuñoa, Santiago, and Arellano, H. F. 2016. "Calculation of self–shielding factor for neutron activation experiments using GEANT4 and MCNP". United States. doi:10.1063/1.4955388.
@article{osti_22608534,
title = {Calculation of self–shielding factor for neutron activation experiments using GEANT4 and MCNP},
author = {Romero–Barrientos, Jaime, E-mail: jaromero@ing.uchile.cl and Universidad de Chile, DFI, Facultad de Ciencias Físicas Y Matemáticas, Avenida Blanco Encalada 2008, Santiago and Molina, F. and Aguilera, Pablo and Universidad de Chile, Depto. de Física, Facultad de Ciencias, Las Palmeras 3425, Ñuñoa, Santiago and Arellano, H. F.},
abstractNote = {The neutron self–shielding factor G as a function of the neutron energy was obtained for 14 pure metallic samples in 1000 isolethargic energy bins from 1·10{sup −5}eV to 2·10{sup 7}eV using Monte Carlo simulations in GEANT4 and MCNP6. The comparison of these two Monte Carlo codes shows small differences in the final self–shielding factor mostly due to the different cross section databases that each program uses.},
doi = {10.1063/1.4955388},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1753,
place = {United States},
year = 2016,
month = 7
}
  • Purpose: Radiopharmaceutical applications in nuclear medicine require a detailed dosimetry estimate of the radiation energy delivered to the human tissues. Over the past years, several publications addressed the problem of internal dose estimate in volumes of several sizes considering photon and electron sources. Most of them used Monte Carlo radiation transport codes. Despite the widespread use of these codes due to the variety of resources and potentials they offered to carry out dose calculations, several aspects like physical models, cross sections, and numerical approximations used in the simulations still remain an object of study. Accurate dose estimate depends on themore » correct selection of a set of simulation options that should be carefully chosen. This article presents an analysis of several simulation options provided by two of the most used codes worldwide: MCNP and GEANT4. Methods: For this purpose, comparisons of absorbed fraction estimates obtained with different physical models, cross sections, and numerical approximations are presented for spheres of several sizes and composed as five different biological tissues. Results: Considerable discrepancies have been found in some cases not only between the different codes but also between different cross sections and algorithms in the same code. Maximum differences found between the two codes are 5.0% and 10%, respectively, for photons and electrons.Conclusion: Even for simple problems as spheres and uniform radiation sources, the set of parameters chosen by any Monte Carlo code significantly affects the final results of a simulation, demonstrating the importance of the correct choice of parameters in the simulation.« less
  • GEANT4 is a Monte Carlo code originally implemented for high-energy physics applications and is well known for particle transport at high energies. The capacity of GEANT4 to simulate neutron transport in the thermal energy region is not equally well known. The aim of this article is to compare MCNP, a code commonly used in low energy neutron transport calculations and GEANT4 with experimental results and select the suitable code for gadolinium neutron capture applications. To account for the thermal neutron scattering from chemically bound atoms [S({alpha},{beta})] in biological materials a comparison of thermal neutron fluence in tissue-like poly(methylmethacrylate) phantom ismore » made with MCNP4B, GEANT4 6.0 patch1, and measurements from the neutron capture therapy (NCT) facility at the Studsvik, Sweden. The fluence measurements agreed with MCNP calculated results considering S({alpha},{beta}). The location of the thermal neutron peak calculated with MCNP without S({alpha},{beta}) and GEANT4 is shifted by about 0.5 cm towards a shallower depth and is 25%-30% lower in amplitude. Dose distribution from the gadolinium neutron capture reaction is then simulated by MCNP and compared with measured data. The simulations made by MCNP agree well with experimental results. As long as thermal neutron scattering from chemically bound atoms are not included in GEANT4 it is not suitable for NCT applications.« less