Browsing by Author "Nguyen, Duy Quang"

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    Fabrication and investigation of the effects of various gadolinium compounds on Ce3+-activated phosphate glasses for scintillation applications
    (Elsevier, 2022-07) Ntarisa, Amos Vincent; Saha, Sudipta; Nguyen, Duy Quang; Kim, HongJoo; Wantana, N; Pandey, Indra Raj; Aryal, Pabitra; Kothan, Suchart; Kaewkhao, Jakrapong
    Ce3+-activated phosphate-based glasses were fabricated for scintillation purposes following melt-quenching technique. Chemical compositions of the glasses were designed in mol. % ratio with formula (62P2O5:20Li2CO3:10X:5Al2O3:3CeBr3 where X Gd2O3/GdF3/GdCl3/GdBr3/GdI3). The amorphous structure of the glasses was verified by the powder X-ray diffraction measurements. Fourier-transform infrared (FTIR) measurements were carried out to study the structural properties of the fabricated glass samples. X-ray-induced luminescence and photoluminescence (PL) spectra were used to investigate the luminescence properties of the glasses. A broad PL excitation band was found for all prepared glasses that refers to Gd3+ and Ce3+ characteristic transitions. GdI3 containing glass sample provided the optimum emission under X-ray and UV (308 nm) excitations peaking at 347 and 341 nm, respectively. The scintillation property of the GdI3 containing glass was studied under 5.5 MeV α-particle from 241Am radiation source and a clear alpha peak was observed with energy resolution of 35.3%. The shortest decay component of the glass sample was observed to be 27.9 ns, 30.7 ns and 29.12 ns under the α-particles, γ-ray, and 266 nm pulsed laser excitations, respectively. In conclusion, the GdI3 prepared glass sample can be used for α -particles detection.
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    Luminescence and scintillation properties of Ce3+-doped P2O5-Li2CO3-GdBr3-Al2O3 glasses
    (Elsevier, 2021-09-01) Ntarisa, Amos Vincent; Saha, Sudipta; Aryal, Pabitra; Kim, HongJoo; Khan, Arshad; Nguyen, Duy Quang; Pandey, Indra Raj; Kaewkhao, Jakrapong; Kothan, Suchart
    A series of glass samples were fabricated with the composition of (65-x)P2O5:20Li2CO3:10GdBr3:5Al2O3:xCeBr3 (where, x = 0.5,1,2,3,4). The powder X-ray diffraction measurements were performed to verify the amorphous structure of the prepared glass samples. Energy-dispersive X-ray spectroscopy showed an interesting phenomenon of oxygen bridging eliminating Br (Bromine) from the initial compounds. The luminescence characteristics of the samples were studied using X-rays and UV–Vis excitations. Characteristics Ce3+ emission was observed at 350 nm including energy transfer from 4f energy state of Gd3+ to 5d energy band of Ce3+. The fast decay component was observed as 37 ns, 42 ns, and 44 ns for the UV, α-particles, and γ-ray excitations, respectively. The intermediate and slow components were observed for α-particles, and γ-rays excitations indicating Gd3+ to Ce3+ energy transfer and 4f-4f transitions of Gd3+ -ions accordingly. The scintillation property was studied with α-particles using a 241Am source.
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    A novel blue-emitting phosphors (CsBaYB6O12:Ce3+): Potential applications in w-LEDs and X-ray phosphors
    (Elsevier, 2021-08-25) Ntarisa, Amos Vincent; D Joseph, Daniel; D, Balaji; Raja, Arumugam; Kim, HongJoo; Nguyen, Duy Quang
    We have synthesized powder samples of pure and Ce3+ doped cesium barium yttrium hexaborate (CsBaYB6O12) using a standard solid-state reaction technique. The prepared samples were characterized by different techniques. Powder X-ray diffraction (PXRD) was used to identify the phase purity of the prepared phosphors. The field emission scanning electron microscopy (FE-SEM) technique was used to examine the size and shape of the synthesized powder samples. The energy-dispersive spectral analysis (EDS) was used to identify the elements present in the synthesized compounds. X-ray-induced luminescence spectra, photoluminescence (PL), and thermoluminescence (TL) analysis were used to investigate the luminescence properties of the prepared compound. The rare earth ion of Ce3+ improves the intrinsic luminescence of CsBaYB6O12 and 4 mol% was found to be the optimal concentration. The dopants found to have two different excitation PL bands at 340 nm and 360 nm which yields the same emission bands of 385 and 417 nm which are well-matched with that found in the X-ray emission bands. The kinetic parameters of the measured experimental TL glow curve has been studied by various standard methods such as deconvolution, Variable heating rate and initial rise method. In this manuscript we report the luminescence properties of the prepared phosphors in a detailed manner for the first time.
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    Novel technique for simultaneous detecting three naturally occurring radon isotopes (222Rn, 220Rn and 219Rn)
    (Elsevier, 2022-11) Ntarisa, Amos Vincent; Kim, HongJoo; Aryal, Pabitra; Nguyen, Duy Quang; Saha, Sudipta
    Radon inspection is becoming increasingly prevalent due to its negative effects on human health. After cigarette smoking, radon is the second leading cause of lung cancer due to its internal dosage through respiration. In this study, we employed a novel liquid scintillation technique to simultaneously detect three naturally occurring radon isotopes (222Rn, 220Rn and 219Rn). The detection method utilises the delayed coincidence technique and the pulse shape discrimination implemented by digital charge comparison. Furthermore, a Monte Carlo simulation was performed to obtain the gamma response functions of the detector using standard 22Na, 60Co and 137Cs gamma sources. Additionally, the detector resolution and energy calibration parameters were determined by comparing the measured and simulated light output distributions. For the measurement, radon gas from the atmosphere was infused into 700 mL of Ultima Gold AB for 48 h. We determined that the minimum detectable activities of 222Rn (238U decay chain), 220Rn (232Th decay chain) and 219Rn (235U decay chain) were 1.7, 1.0 and 1.2 mBq/l, respectively. The proposed novel technique offers a potential application for detecting all three naturally occurring radon isotopes in water samples.
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    Scintillation performance of the Ce3+ -activated lithium phosphate glass
    (Elsevier, 2022-10) Saha, Sudipta; Ntarisa, Amos Vincent; Nguyen, Duy Quang; Luan, NT; Vuong, PQ; Kim, HongJoo; Intachai, N; Kothan, Suchart; Kaewkhao, Jakrapong
    Ce3+ -doped phosphate glasses with intense luminescence were reported extensively for radiation detection in recent decades. With the same intension, we fabricated glasses of composition 45P2O5:35Li2O:(10-x)GdI3:5Al2O3:5Ca2CO3:xCeBr3 (x = 1, 2, 3, 5) in molar ratio using conventional technique followed by thermal annealing. The luminescence studies confirmed the energy transfer process from Gd3+ to Ce3+ -ions. The scintillation measurements of the optimized sample were performed under the excitation of α -particles and γ-rays. A photopeak was detected under γ-ray excitation at 662 keV energy from 137Cs source. The estimated absolute light yield was 1600 ± 200 Photons/MeV. The shortest component of the decay time under α -particles and γ -ray excitations was found 32.5 ± 0.3 ns and 39.9 ± 0.4 ns, respectively. In the future, the glass configuration can be engineered to improve radiation detection performance.
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    Synthesis and elemental analysis of gadolinium halides (GdX3) in glass matrix for radiation detection applications
    (Elsevier, 2022-07) Saha, Sudipta; Ntarisa, Amos Vincent; Nguyen, Duy Quang; Kim, HongJoo; Kothan, Suchart; Kaewkhao, Jakrapong
    Numerous researchers were intrigued to glasses for radiation detection and scintillation applications in nuclear and high-energy physics research. To mitigate the requirements of density and luminescence enhancement, gadolinium (Gd) compounds are widely practiced. Gd halides (GdX3) are hygroscopic salts that can function as excellent sensitizers in a glass network to improve activator (Ce) luminescence. To ensure the elemental abundance of the constituents in glass samples after high temperature combustion, EDX reports at both the intermediate and final phases of the glass samples can be useful. However, EDX analysis was unable to detect halogens in glass substances in their intermediate and final forms. The implications were examined on the basis of prior literature indicating the feasibility of high temperature combustion in an air environment. Nevertheless, it was discovered that transmittance spectra are essential for the performance of radioluminescence and scintillation features. Two samples that were previously enriched with GdI3 had transmittance values more than 55% at the X-ray generated emission peak point. α -peaks with an energy resolution (FWHM) of 29% and 31% were obtained utilizing these samples. The scintillation decay projections from these two samples were fitted with three exponential decay components, with the shortest components being 30.6 ns and 29.5 ns, contributing 38% and 37.4%, respectively.