Papers by Keyword: Energy Resolution

Abstract: Nowadays, radioactive materials are being applied in medical imaging. Because humans cannot observe radiation, radiation detection materials are very important to humans. A scintillator is a material that can change gamma photons to visible photons. Good scintillators should have the following properties: high scintillation light yield, good energy resolution, and high density. In this work, the scintillation light yield property of CWO crystals was studied due to its interesting properties, such as high stopping power and low hygroscopicity. CWO crystals were compared with BGO crystals. From the results, it was found that the BGO crystals showed higher scintillation light yield value at 662 keV energy from ¹³⁷Cs radioactive source than the CWO crystals, resulting in better energy resolution value. The intrinsic light yield and loss parameters for both crystals are also presented in this work.

Abstract: The luminescence and gamma-ray detection properties of Gd₂SiO₅: Ce single crystal scintillator were investigated. The light yield (LY) and energy resolution were measured using R6231 photomultiplier. At 662 keV γ-rays, high LY of 10,300 photons /MeV and good energy resolution of 6.4 % were obtained. The intrinsic LY and light loss coefficient under excitation with 662 keV γ-rays were evaluated. The mass attenuation coefficient for 662 keV γ-rays was also measured by transmission method and compared with the theoretical value calculated by WinXCom program.

Abstract: The study of photon interactions with matter is very important in many fields such as scientific, industry, medical imaging, biological applications, dosimetry, and radiation shielding for their potential use in radiation physics. Scintillating materials become a main part in detection and spectroscopy of high energy photons. The goal of this work is to study an interaction of 662 keV γ-rays with scintillating materials, namely the LYSO(Ce) and BGO crystals. The light output, energy resolution, intrinsic resolution, and photo-fraction of both crystals with the same size of 5x5x3 mm³ were measured using photomultiplier tube (PMT) readout. The result showed that the light yield of the LYSO(Ce) crystal is much more better than that of the BGO crystal, while its photo-fraction is worse than that of the BGO crystal.

Abstract: In the present day, inorganic scintillating crystals become a main part in detection and spectroscopy of nuclear particles and high energy photons, more spectively in X/g-ray imaging. The good properties for the scintillating crystals used in these applications require high photon yield, high stopping power, good energy resolution, good light yield proportionality, and minimal afterglow. The main useful of Ce-doped Lu_0.7Y_0.3AlO₃ (LuYAP(Ce)) are high stopping power and non-hygroscopic which are expected to be key ingredients for medical imaging. In this work, we studied the light yield non-proportionality and energy resolution of LuYAP(Ce) crystal with the energy range from 31 to 1,274.5 keV using photomultiplier tube (PMT) readout. The intrinsic resolution of the LuYAP(Ce) crystal has been determined after correcting the measured PMT resolution. The results showed that the non-proportional response of the crystals was strongly correlated with the intrinsic resolution of the crystals.

Abstract: Cadmium zinc telluride (CZT) material is one of the preferred materials for the fabrication of X-ray and gamma-ray detector. In this paper, it is presented an experimental detector system based on pixellated CZT semiconductor detector. The aim of this study is to get the photon energy suitable for different thickness detector, different photon energy acts on pixel CdZnTe detector of different thickness. We can obtain the energy spectrum estimation, energy resolution and peak efficiency by the experiment and simulation with the radiation source of 241Am and 137Cs acting on pixel CdZnTe detector. From experiment results, it can be found that at the high energy of ⁶⁶²keV the thicker CdZnTe detector is high. The characteristic of detector is better at the low energy when the detector thickness is thinner.

Abstract: This work was investigated on gamma ray scintillation response of inorganic scintillators. BGO and CsI(Tl) was carried out in the energies ranging from 59 keV to 1332 keV. The scintillation responses of the crystals were measured using photomultiplier tube (R1306 PMT) readout. The light yield non-proportionality and energy resolution were analyzed with Gamma Acquisition & Analysis program. The photofraction for both crystals was determined and compared with the cross-section ratio which calculated by WinXCom program.

Abstract: The marine radioactivity measurement is the low-level radiation measurement, whose accuracy mainly depends on the material and design of the detector. However, the currently research results mainly focus on the qualitative research. In this paper, a Monte Carlo code MCNP was utilized to simulate the comparation of the energy spectra of several relevant γ rays recorded by detectors immersed in seawater, The detection efficiency and the effective detection distance of these detectors to the radionuclides of ¹³⁷Cs dispersed in seawater were calculated．The results of our experiment shown that the effective detection distance of these detctors to γ radionuclides depends on the detector material and γ-ray energy. The LaBr detector has the best price performance ratio, however, considering the balance between the low-cost and highly detection efficiency, the NaI detector is also a better choice.

Abstract: The performances of Ce-doped Lu₃Al₅O₁₂ (LuAG:Ce) and LaBr₃ (LaBr₃:Ce) scintillators were compared for γ-ray detection using photomultiplier tube ( XP5500B PMT) readout. For 662 keV γ-rays (137Cs source), an energy resolution of 3.5% obtained for LaBr₃:Ce is much better than that of 6.7% obtained for LuAG:Ce, while the estimated photofraction of 28.0% for LuAG:Ce is higher than that of 16.2% for LaBr₃:Ce. The light yield non-proportionality and energy resolution versus γ-ray energy were measured and the intrinsic resolution of the crystals was calculated. The coincidence timing resolution, obtained in this work for 511 keV annihilation quanta, was 583 ps and 204 ps, respectively, for LuAG:Ce –BaF₂ and LaBr₃:Ce – BaF₂ detectors.

Abstract: The CdZnTe (CZT) devices with various screening depth in dimensions 3×3×6mm³ were fabricated. The influence of Ring length (screening depth) and length of crystal on the electric field distribution in CZT devices has been explored by finite element method. The results indicated that ring length (screening depth) plays an important role on the detecting performance of CZT Frisch-ring devices. Longer screening depth gives rise to an electric field which is compressed more greatly. Measured spectra indicated that extreme compressed electric field could reduce detecting resolution. A FWHM energy resolution of approximately 3.71% at 662 keV was obtained for a device with dimensions 3×3×6mm³ and 4.8mm screening depth.

Abstract: The scintillation response of Lu_1.8Y_0.2SiO₅:Ce (LYSO:Ce) and LaCl₃:Ce scintillators were compared under g-ray excitation using photomultiplier tube (PMT) readout. For 662 keV g-rays (¹³⁷Cs source), energy resolution of 4.5±0.2% obtained for LaCl₃:Ce coupled to XP5200B PMT is much better than that of 8.2±0.4% for LYSO:Ce. The non-proportionality of the light yield and energy resolution versus g-ray energy were measured and the intrinsic resolution of the crystals was calculated. Special attention was devoted to the correlation between intrinsic resolution and non-proportional response of scintillators.