Neutron scattering in concrete and wood: Part II--oblique incidence

Abstract

The knowledge of neutron reflection coefficients is of practical interest when projecting the shielding of radiotherapy rooms, since it is known that about 75% of the neutrons at the maze entrance of these rooms are scattered neutrons. In a previous paper, the energy spectra of photoneutrons were calculated, when reflected by ordinary, high-density concrete and wood barriers, using the MCNP5 code, considering normal incidence and neutron incident energies varying between 0.1 and 10 MeV. It was found that the mean energy of the reflected neutrons does not depend on the reflection angle and that these mean energies are lower in wood and barytes concrete, compared with ordinary concrete. In the present work, the simulation of neutron reflection coefficients were completed, considering the case when these particles do not collide frontally with the barriers, which constitute the radiotherapy room walls. Some simulations were also made to evaluate how neutron equivalent doses at the position of the room door is affected when the maze walls are lined with neutron absorbing materials, such as wood itself or borated polyethylene. Finally, capture gamma rays dose at the entrance of rooms with different maze lengths were also simulated. The results were discussed in the light of the albedo concepts presented in the literature and some of these results were confronted with others, finding good agreement between them.

Neutron and photon scattering properties of high density concretes used in radiation therapy facilities: A Monte Carlo study

“…This discrepancy stems from the fact that there are different neutron-neutron elastic and inelastic cross-sections for atoms constitute the studied HDC concretes. Studies attributed this difference in the reflected neutron fluence to the H content in different concretes and the neutron-neutron interaction cross-sections of other major components such as SiO 2 [15,16].…”

“…Studies have reported that about 75% of the neutrons at the maze entrance of these rooms are scattered neutrons [14,15]. Also, the studies have shown the fluence of scattered photons and neutrons per angle by different shielding materials as well as concretes depend on the composition of concretes and used shielding materials.…”

Monte Carlo Calculation of linear attenuation coefficients and photon scattering properties of novel concretes loaded with Osmium, Iridium and Barite nanoparticles

“…Studies have reported that 75% of the neutrons at the entrance door of the maze are scattered neutrons. 16,17 Studies have also publicized that the intensity of photons and neutrons scattered at any angle by different radiation shielding materials and concretes depends on the composition of the concrete and shielding materials used.…”