ESTIMATION OF NEUTRON SCATTER CORRECTION FOR CALIBRATION OF PERSONNEL DOSIMETER AND DOSERATEMETER AGAINST 241Am–Be SOURCE—MONTE CARLO SIMULATION AND MEASUREMENTS

Abstract

Neutron scatter contributions as a function of distance along the transverse axis of 241Am-Be source were estimated by three different methods such as shadow cone, semi-empirical and Monte Carlo. The Monte Carlo-based FLUKA code was used to simulate the existing room used for the calibration of CR-39 detector as well as LB6411 doseratemeter for selected distances from 241Am-Be source. The modified 241Am-Be spectra at different irradiation geometries such as at different source detector distances, behind the shadow cone, at the surface of the water phantom were also evaluated using Monte Carlo calculations. Neutron scatter contributions, estimated using three different methods compare reasonably well. It is proposed to use the scattering correction factors estimated through Monte Carlo simulation and other methods for the calibration of CR-39 detector and doseratemeter at 0.75 and 1 m distance from the source.

Estimation of scattered radiation influence on neutron beams at a calibration laboratory using Monte Carlo simulation of a long counter

“…This scattered radiation varies depending on the size and material of the laboratory (walls, floor and ceiling). The neutron spectrum measured at a given point is not the same as the spectrum emitted by the neutron source, which directly influences the reading of the instrument to be calibrated and causes systematic calibration errors [8,9,10].…”

“…To choose a reliable method to assess scattered radiation, the calibration distance, the source type, and the laboratory dimensions have to be analyzed [3]. The determination of scattered radiation can be performed experimentally using the methods recommended by ISO 8529-2 [11], which are: the Semi-Empirical Method (SEM), the Reduced Fitting Method (RFM), the Generalized Fit Method (GFM) and the Shadow Cone Method (SCM), and through simulation using Monte Carlo Code (MCNP), which allows a more detailed assessment [11,10].…”