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ABSTRACT
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ABSTRACT Room-temperature scintillation properties were determined for five Eu$^{2+}$ doped compounds in the Ba-Si-O ternary system: Ba$_{2}$ SiO$_{4}$ , BaSiO$_{3}$ , Ba$_{2}$ Si$_{3}$ O$_{8}$ , Ba$_{5}$ Si$_{8}$ O$_{21}$ , and... more
ABSTRACT Room-temperature scintillation properties were determined for five Eu$^{2+}$ doped compounds in the Ba-Si-O ternary system: Ba$_{2}$ SiO$_{4}$ , BaSiO$_{3}$ , Ba$_{2}$ Si$_{3}$ O$_{8}$ , Ba$_{5}$ Si$_{8}$ O$_{21}$ , and BaSi$_{2}$ O$_{5}$ . These materials were synthesized as polycrystalline powders from conventional solid-state reactions. Of the materials studied, Ba $_{2}$SiO $_{4}$: 0.2% Eu $^{2+}$ is the most luminous scintillator having a luminosity of 2.7 times the reference material, Bi $_{4}$Ge $_{3}$O $_{12}$. Its scintillation decay curve is comprised of two components with lifetimes of 242 and 668 ns.
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... The values of constants valid for the cupric sulphate pentahydrate (BROUL et al.) are A = -24.60421, B = 459.4664, and ... At the end of a batch experiment, the cumulative size distributions of product crystals can be obtained ... 178... more
... The values of constants valid for the cupric sulphate pentahydrate (BROUL et al.) are A = -24.60421, B = 459.4664, and ... At the end of a batch experiment, the cumulative size distributions of product crystals can be obtained ... 178 GIULIETTI: et al.: Crystallization of Copper Sulphate ...
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Research Interests: Engineering, Biomedical Engineering, Image Processing, Computed Tomography, Nuclear medicine, and 13 morePositron Emission Tomography, Control system, Data acquisition, Look up Table, Circuit Design, High Speed, Computer Control, Single Photon Emission Computed Tomography, Data Flow Diagram, Computerized tomography, First In First Out, Data Acquisition System, and Parallel Architecture
Research Interests: Physics, Biomedical Engineering, Computed Tomography, Nuclear medicine, Science and Technology, and 12 morePositron Emission Tomography, Control system, Time Delay, High Resolution, Single Photon Emission Computed Tomography, Computerized tomography, Data Processing, Spatial resolution, Detector, High Spatial Resolution, Scintillation, and radiation detector
Research Interests: Physics, Biomedical Engineering, Image Processing, Computed Tomography, Nuclear medicine, and 14 moreControl system, Beta decay, IEEE, Time Delay, Alkali Metals, Look up Table, Nuclear science, Single Photon Emission Computed Tomography, Computerized tomography, Spatial resolution, Point Spread Function, Structural model, Time window, and radiation detector
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In this paper we report on the scintillation properties of cerium doped strontium - and barium hafnate. Radioluminescence, pulse height, scintillation decay and timing spectra are presented. Radioluminescence spectra of SrHfO3:Ce3+ and... more
In this paper we report on the scintillation properties of cerium doped strontium - and barium hafnate. Radioluminescence, pulse height, scintillation decay and timing spectra are presented. Radioluminescence spectra of SrHfO3:Ce3+ and BaHfO3:Ce3+ consist of a broad band due to Ce3+ emission peaking at 410 nm and 400 nm, respectively. The light yield of BaHfO3:Ce3+ and SrHfO3:Ce3+ is approximately 40
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ABSTRACT Recently, scintillation has been observed in Ce-doped YI3, YBr3, and YCl3 crystals. In particular, YI3 has been reported to be among the scintillators with the highest luminosity. In this work, we present a systematic study of... more
ABSTRACT Recently, scintillation has been observed in Ce-doped YI3, YBr3, and YCl3 crystals. In particular, YI3 has been reported to be among the scintillators with the highest luminosity. In this work, we present a systematic study of scintillation in any of the four YHa3:Ce materials where Ha = F, Cl, Br, I, using ab initio calculations. Last year, our group demonstrated successful application of a method of gauging scintillation properties of Ce-doped crystals based on first-principle calculations using density functional theory. This method has been developed as an integral component of a High Throughput Scintillator Discovery facility based at the Lawrence Berkeley National Lab. By analyzing the energies and spatial localization of the highest occupied band in the ground state and in the lowest excited state, we are able to make qualitative predictions about the possibility of scintillation in Ce-doped compounds. In this paper we present the details of our theoretical approach in application to yttrium halides and compare them with the available experiments. Our results yield a prediction of Ce-based scintillation for all four materials: YF3, YCl3, YBr3 and YI3 and are in correspondence with the available experimental data. We believe that our method is the first use of first-principles calculations to predict some of the factors necessary for the activation of Ce3+ ions in crystals.
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AbstractIn this communication, we investigate the scintillation properties of LaBr3:Ce as a function of Ce concentration. We have studied crystals nominally doped with 0.5%, 5%, 10%, 20%, and 30%Ce (by mole). Previous reports suggest... more
AbstractIn this communication, we investigate the scintillation properties of LaBr3:Ce as a function of Ce concentration. We have studied crystals nominally doped with 0.5%, 5%, 10%, 20%, and 30%Ce (by mole). Previous reports suggest that as the Ce content increases, there is a ...
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Research Interests: Biomedical Engineering, Image Processing, Computed Tomography, Antimatter, Crystals, and 15 moreIsotopes, Deconvolution, Beta decay, Detectors, Integral Transforms, High Resolution, Functions, Carbon Isotope, Frequency Dependence, Fourier transform, Computerized tomography, Antiparticles, Fourier Transformation, Elementary Particles, and Fermions
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A theoretical approach based on first-principles calculations is used to select candidate Ce activated scintillator materials for synthesis. Our theoretical approach involves the calculation of the ground state band structure of the... more
A theoretical approach based on first-principles calculations is used to select candidate Ce activated scintillator materials for synthesis. Our theoretical approach involves the calculation of the ground state band structure of the Ce-doped material as well as the calculation of the (Ce3+)* excited state. From our theoretical studies of known scintillators and non-scintillators we have developed a set of criteria
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Research Interests: Physics, Biomedical Engineering, Computed Tomography, Nuclear medicine, Semiconductor Devices, and 9 morePositron Emission Tomography, Crystals, Detectors, High Resolution, Single Photon Emission Computed Tomography, Computerized tomography, Spatial resolution, Signal to Noise Ratio, and radiation detector
A systematic study of several hundred inorganic crystal structures have been performed by means of electronic structure calculations with the goal of finding potential new scintillator materials for synthesis and testing. All X-ray or... more
A systematic study of several hundred inorganic crystal structures have been performed by means of electronic structure calculations with the goal of finding potential new scintillator materials for synthesis and testing. All X-ray or neutron diffraction measurements of crystals containing one or more of the heavy elements Tl, Hg, Pb or Bi and with all sites in the unit cell fully occupied were extracted from the Inorganic Crystal Structure Database (ICSD). A Full-Potential Linear Muffin-Tin Orbital (FP-LMTO) implementation with a LDA exchange-correlation energy functional was used for solving the electronic structure. The data was analyzed for density, photoelectric fraction at 511 keV, direct/indirect band gap, LDA band gap enegy, energy dispersion, bandwidths, degree of covalency, electronic density distribution of upper valence electrons, electron and hole masses, valence and conduction band parity, etc. Preliminary computational results are presented for a number of representat...
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The past half century has witnessed the discovery of many new inorganic scintillator materials and numerous advances in our understanding of the basic physical processes governing the transformation of ionizing radiation into... more
The past half century has witnessed the discovery of many new inorganic scintillator materials and numerous advances in our understanding of the basic physical processes governing the transformation of ionizing radiation into scintillation light. Whereas scintillators are available with a good combination of physical properties, none provides the desired combination of stopping power, light output, and decay time. A review of the numerous scintillation mechanisms of known inorganic scintillators reveals why none of them is both bright and fast. The mechanisms of radiative recombination in wide-band gap direct semiconductors, however, remain relatively unexploited for scintillators. We describe how suitably doped semiconductor scintillators could provide a combination of high light output, short decay time, and linearity of response that approach fundamental limits.
Trivalent bismuth luminescence is reported in three Sillen bismuth oxyhalide phases, SrBiO2Cl, BaBiO2Cl, and BaBiO2Br. These compounds exhibit Bi 6s6p → 6s emission under UV and X-ray radiation. At room temperature, BaBiO2Cl shows the... more
Trivalent bismuth luminescence is reported in three Sillen bismuth oxyhalide phases, SrBiO2Cl, BaBiO2Cl, and BaBiO2Br. These compounds exhibit Bi 6s6p → 6s emission under UV and X-ray radiation. At room temperature, BaBiO2Cl shows the most intense light emission, with spectral and decay properties similar to those found in Bi4Ge3O12 (BGO). At low temperatures, each phase show an increase in the photoluminescence intensities and a narrowing of the emission peaks. In contrast to the temperature dependence of BGO, X-ray excited luminescence intensities of all three phases remain relatively constant throughout the temperature range 10 – 295 K. This result indicates that the Sillen phases undergo less thermal quenching than BGO. The low temperature and room temperature radio-luminescence decay times were determined from pulsed xray measurements. At room temperature, SrBiO2Cl exhibits faster decays than BGO, while, BaBiO2Cl and BaBiO2Br have decay times similar to BGO.
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A systematic study of several hundred inorganic crystal structures have been performed by means of electronic structure calculations with the goal of finding potential new scintillator materials for synthesis and testing. All X-ray or... more
A systematic study of several hundred inorganic crystal structures have been performed by means of electronic structure calculations with the goal of finding potential new scintillator materials for synthesis and testing. All X-ray or neutron diffraction measurements of crystals containing one or more of the heavy elements Tl, Hg, Pb or Bi and with all sites in the unit cell fully occupied were extracted from the Inorganic Crystal Structure Database (ICSD). A FullPotential Linear Muffin-Tin Orbital (FP-LMTO) implementation with a LDA exchange-correlation energy functional was used for solving the electronic structure. The data was analyzed for density, photoelectric fraction at 511 keV, direct/indirect band gap, LDA band gap enegy, energy dispersion, bandwidths, degree of covalency, electronic density distribution of upper valence electrons, electron and hole masses, valence and conduction band parity, etc. Preliminary computational results are presented for a number of representati...
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Abstract A hydrogen bubble chamber has been calibrated at 7, 14 and 21 kG for low momentum electrons by measuring the 0.5 MeV and 1 MeV internal conversion electrons from a 207Bi source. The source was mounted on thin polyester strips... more
Abstract A hydrogen bubble chamber has been calibrated at 7, 14 and 21 kG for low momentum electrons by measuring the 0.5 MeV and 1 MeV internal conversion electrons from a 207Bi source. The source was mounted on thin polyester strips which were suspended in the chamber. The two conversion lines are easily resolved at 7 and 14 kG but are only barely resolved at 21 kG. At 14 kG the 1 MeV line has a fwhm, Γ = 25%. The momentum calibration at this energy is good to ( p p i ) 0.6 (|p−p i | 2.6 +S 2.6 ) where pi is the true momentum and S ≈ 0.5piΓ. The variation of Γ with momentum is found by supplementing the 207Bi data with measurements of the high energy end of the μ-decay spectrum. Tests have been made for momentum dependent inefficiencies.