Scintillation and Luminescence Properties of the Zinc Oxide (ZnO) Doped Frit Crystal Under Gamma Radiation

The main objective of this study is to determine the characteristics of the scintillation and luminescent for Zinc Oxide (ZnO). Two groups of ZnO were prepared: pure (P338) and doped (P338Frit). This study investigates the scintillation and luminescent properties of the prepared ZnO in both powder and crystal forms. The NaI(Tl) scintillator is used as a tool for the control scintillator. It is a crystal that is commercially utilized in many radiation detecting fields. The P338 and P338Frit were used as the scintillator in the experimental setup. The P338 and P338Frit were bombarded with gamma photons of 241Am and 137Cs. The set up was connected to Multichannel Analyzer (MCA) to analyse its gamma spectrum. The scintillation occurrence is followed by the occurrence of luminescence in order for photon interactions to be detected by the MCA system. The photons detected are called count. However, self-absorption of the light is common which prevail the count from being recorded even though the scintillation occurs. The Compton continuum and photoelectric peak of the interaction were not distinguished. In conclusion, the characteristics of the luminescence and scintillation for the prepared ZnO were observed, however, the gamma spectrum peaks recorded were inconclusive.

Validation of aGeant4model of the X-ray fluorescence microprobe at the Australian Synchrotron

AGeant4Monte Carlo simulation of the X-ray fluorescence microprobe (XFM) end-station at the Australian Synchrotron has been developed. The simulation is required for optimization of the scan configuration and reconstruction algorithms. As part of the simulation process, a Gaussian beam model was developed. Experimental validation of this simulation has tested the efficacy for use of the low-energy physics models inGeant4for this synchrotron-based technique. The observed spectral distributions calculated in the 384 pixel Maia detector, positioned in the standard back-scatter configuration, were compared with those obtained from experiments performed at three incident X-ray beam energies: 18.5, 11.0 and 6.8 keV. The reduced χ-squared (\chi^{2}_{\rm{red}}) was calculated for the scatter and fluorescence regions of the spectra and demonstrates that the simulations successfully reproduce the scatter distributions. Discrepancies were shown to occur in the multiple-scatter tail of the Compton continuum. The model was shown to be particularly sensitive to the impurities present in the beryllium window of the Maia detector and their concentrations were optimized to improve the \chi^{2}_{\rm{red}} parameterization in the low-energy fluorescence regions of the spectra.

Unfolding Low-Energy Gamma-Ray Spectrum Obtained with NaI(Tl) in Air Using Matrix Inversion Method

Matrix inversion method is presented to unfold the gamma-ray spectrum obtained with an NaI(Tl) detector using several standard gamma-ray sources. The method is based on response matrix generated by Monte Carlo simulation of mono-energy gamma-ray photon ranging from 10 keV to 1 MeV in step of 10 keV. The comparison of the measured and simulated response function was also performed in order to validate the simulation response function. Good agreement was achieved around the photo-peak region of the spectrum, but slight deviation was observed at low energy region especially at Compton continuum region. The Compton continuum count was significantly transferred into the corresponding photo-peak and consequently the peak to background ratio was improved substantially by the application of the unfolding method. Therefore, small peak can be identified and analyzed that would otherwise be lost in the background. Keywords: Gamma-ray spectrum; Unfold; NaI(Tl). © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i2.4372 J. Sci. Res. 2 (2), 221-226 (2010)