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The use of neutron activation analysis (NAA) sometimes has limitations with the identification of specific gamma ray peaks due to spectral interferences. The implementation of gamma-gamma coincidence techniques using the XIA Pixie-16 system has demonstrated the ability reduce many of these challenges. Experiments were performed on two different NIST reference materials using gamma-gamma coincidence techniques to identify long-lived radionuclides that are often difficult to evaluate due to various spectral interferences. The experiments have shown that utilizing gamma-gamma coincidence with the XIA Pixie-16 system for 177mLu, 124Sb, 160 Tb, 175Yb, and 153Sm can eliminate spectral interferences and high backgrounds due to Compton scattering. [ABSTRACT FROM AUTHOR]

This study aims to formulate semi-empirical processing applied to analyze simulated and experimental scattering spectra on pipeline samples for estimating the intensity of the single scattering component for the Compton scattering technique. Firstly, a procedure has been developed based on probability density functions of each scattering component, which are obtained by GEANT4. Secondly, sixteen targets are simulated with MCNP6 to validate the proposed procedure. It is shown that the relative deviation for all samples is under 3%. Thirdly, the nine calculated thickness of pipeline samples is determined with a maximum relative deviation lower than 5% in comparing to calibration thickness. [ABSTRACT FROM AUTHOR]

In this study, various detector configurations have been investigated in order to explore the optimal condition for decay rate measurements of radioactive samples using gamma spectroscopy technique. A limitation of detecting low energy gamma rays from decaying radioactive nuclei, is the Compton background which can be significantly reduced by rejecting Compton scattered events through active Bismuth germanate (BGO) shielding. On the other hand, for a CLOVER detector without BGO shielding, one can place the radioactive samples very close to the detector for enhancing geometrical efficiency. A single crystal High Purity Germanium (HPGe) detector can also be used for decay rate measurements. In order to measure the decay rate of nuclei decaying via gamma emission with reasonable intensity, optimal close geometry options have been investigated for various HPGe detector configurations. [ABSTRACT FROM AUTHOR]

Digital pulse processing methods have various applications in radiation spectroscopy due to their unique properties. Here, the effect of light reflector on the response of a large plastic scintillator with different reflective coverings (Teflon tape, aluminum foil and black tape) coupled to a fast photomultiplier tube is investigated based on some extracted anode pulse features. Results showed that the pulse features were changed according to the reflection coefficient of the covering. For instance, the fall time of the average anode pulse shape for Teflon tape, aluminum foil and black tape coverings are 10.46, 6.88 and 3.65 ns, respectively. [ABSTRACT FROM AUTHOR]

In this study, the noise resulting from Compton scattering was quantified when gamma images were acquired with a 50-mm thick scintillator array detectors, and the solution method was proposed to its elimination. To perform it, a system capable of recording the events and occurrence times at each one of the 144 scintillator array elements has been developed. This study also presents that the Compton noise was not the dominant source of image quality degradation in the experiment, but its negative influence of the Monte Carlo simulation can increase greatly to lower detection threshold energies. [ABSTRACT FROM AUTHOR]

In this work, we propose a semi-empirical method for determining the thickness of pipe-wall, of which the determination is performed by combining the experimental and Monte Carlo simulation data. The testing measurements show that this is an efficient method to measure the thickness of pipe-wall. In addition, this work also shows that it could use a NaI(Tl) scintillation detector and a low activity source to measure the thickness of pipe-wall, which is simple, quick and high accuracy method. [ABSTRACT FROM AUTHOR]

In this work, an advanced gamma spectrum processing technique is applied to analyze experimental scattering spectra for determining the thickness of C45 heat-resistant steel plates. The single scattering peak of scattering spectra is taken as an advantage to measure the intensity of single scattering photons. Based on these results, the thickness of steel plates is determined with a maximum deviation of real thickness and measured thickness of about 4 %. Monte Carlo simulation using MCNP5 code is also performed to cross check the results, which yields a maximum deviation of 2 %. These results strongly confirm the capability of this technique in analyzing gamma scattering spectra, which is a simple, effective and convenient method for determining material thickness. [ABSTRACT FROM AUTHOR]