Fast Computation of Pulse Height Spectra Using SGRD Code

Philippe Humbert,Boukhmès Méchitoua

doi:10.1051/epjconf/201715301004

Philippe Humbert, Boukhmès Méchitoua

Open Access

https://doi.org/10.1051/epjconf/201715301004

Copy DOI

Abstract

SGRD (Spectroscopy, Gamma rays, Rapid, Deterministic) code is used for fast calculation of the gamma ray spectrum produced by a spherical shielded source and measured by a detector. The photon source lines originate from the radioactive decay of the unstable isotopes. The emission rate and spectrum of these primary sources are calculated using the DARWIN code. The leakage spectrum is separated in two parts, the uncollided component is transported by ray-tracing and the scattered component is calculated using a multigroup discrete ordinates method. The pulsed height spectrum is then simulated by folding the leakage spectrum with the detector response functions which are pre-calculated using MCNP5 code for each considered detector type. An application to the simulation of the gamma spectrum produced by a natural uranium ball coated with plexiglass and measured using a NaI detector is presented.

Highlights

Real time applications require fast and accurate calculation of the detected gamma-ray spectra produced by shielded sources. For this purpose the SGRD (Spectroscopy, Gamma rays, Rapid, Deterministic) code [1] that was used to calculate the leakage spectra of onedimensional spherical assemblies has been updated in order to take into account the response function of various types of detectors
In the following we recall the methods used in SGRD to calculate the leakage spectra, we describe the pre-calculation of detector response functions (DRF) using Monte Carlo code MCNP5 [3] simulations and we show some numerical results concerning the simulation of a natural uranium ball coated with plexiglass and measured using a NaI detector
As an example we present the simulation of a pulse height spectra obtained with a scintillation sodium iodide detector and a spherical source made of a natural uranium ball surrounded by a plexiglass shell as shown in figure 6

Summary

Introduction

Real time applications require fast and accurate calculation of the detected gamma-ray spectra produced by shielded sources. For this purpose the SGRD (Spectroscopy, Gamma rays, Rapid, Deterministic) code [1] that was used to calculate the leakage spectra of onedimensional spherical assemblies has been updated in order to take into account the response function of various types of detectors. In the following we recall the methods used in SGRD to calculate the leakage spectra, we describe the pre-calculation of detector response functions (DRF) using Monte Carlo code MCNP5 [3] simulations and we show some numerical results concerning the simulation of a natural uranium ball coated with plexiglass and measured using a NaI detector. The SGRD input/output flow diagram for gamma spectra simulation is presented in figure 1

Gamma-Ray Spectra

Leakage spectra

Detector response Function