Characteristics of BGO Scintillation Detector in Gamma Ray Measurements

Abstract

Gamma ray spectroscopy is an analytical approach used to quantify the energy distribution of gamma rays emitted from radioactive sources. This technique can be used for various purposes such as research, health, radioisotope use and astrophysics etc. Radioactive sources emit gamma rays of different energies and intensities. In this work, gamma ray sources Cs137, Mn54, Na22 and Co60 are used for studying the interaction of the gamma radiations with the scintillation detector, Bismuth Germanate (BGO) and Sodium Iodide NaI(Tl)). Energy calibration, efficiency calculations and validation of energy calibrations is done for the experimentally measured data. To study the detector performance, a quantitative comparison between BGO and NaI(Tl) detector is established on the basis of energy resolution.

Theoretically, the main purpose here is to obtain gamma ray spectra by means of a scintillation detector (BGO) by applying Monte Carlo simulation method using the MCNP5 code. The MCNP is a software package, used to simulate statistical processes which allows generating random numbers and the result is taken as an average of numbers observed. The MCNP5 program in general, allows the simulation of the following physical processes: photo-electric effect, Compton Effect, electron positron pair generation and processes involving interaction of charged particles with matter. The gamma rays recorded by the detector are converted into electrical pulses and the gamma ray spectra are acquired. The distance between source and detector and thickness of the detector surface are taken as variable parameters during the acquisition of gamma ray spectra in simulation process. The efficiency for a specific geometry of BGO based gamma spectrometer is estimated experimentally and validated theoretically by comparing the results of the two approaches.