Showing papers by "C.W.E. van Eijk published in 2003"
01 Jan 2003
TL;DR: In this article, the authors compared the properties of Lu/sub 2(1-x)/Y/Sub 2x/SiO/sub 5/ (Ce: LPS) with those of another recently developed cerium doped lutetium pyrosilicate, LPS (Cerium-Doped Lutetsilicate), and showed that the luminescence efficiency remains very high when the temperature increases up to 450 K.
Abstract: Cerium doped lutetium pyrosilicate Lu/sub 2/Si/sub 2/O/sub 7/ (Ce: LPS) scintillator presents high light output (average value: 26,300 ph/MeV), a relatively good energy resolution (10%) and a fast decay time (38 ns) without afterglow. The luminescence efficiency remains very high when the temperature increases up to 450 K. It makes this new scintillator very attractive. We compare its properties to those of another recently developed cerium doped silicate, Ce: Lu/sub 2(1-x)/Y/sub 2x/SiO/sub 5/ (LYSO).
174 citations
TL;DR: In this article, the authors explore the use of quartz optically stimulated luminescence (OSL) dating for reconstructing coastal evolution on a time scale of decades to a few hundred years.
173 citations
TL;DR: In this paper, a new inorganic scintillator, Lu2Si2O7:Ce3+ (LPS), was proposed for medical imaging, which can be readily pulled from the melt.
Abstract: Cerium doped lutetium pyrosilicate Lu2Si2O7:Ce3+ (LPS), a new inorganic scintillator, displays particularly promising performance. This material can be readily pulled from the melt. A high light output (average value: 26 300 ph MeV−1), a relatively good energy resolution (9%) and a fast decay time (38 ns) without afterglow make this new scintillator very attractive, in particular for medical imaging. Optical characterizations and scintillation properties of LPS:Ce large single crystals are presented, including timing properties and study of the scintillation yields as a function of incident energy.
147 citations
TL;DR: In this paper, the properties of the 5D levels of the five levels of Ce3+ and the crystalline environment were studied in the 100-400 nm wavelength region with time resolved spectroscopy at temperatures between 10 and 300 K.
Abstract: The properties of Ce3+ in CaBPO5, LiCaPO4 and Li2CaSiO4 have been studied in the 100–400 nm wavelength region with time resolved spectroscopy at temperatures between 10 and 300 K. Emphasis is on the relationship between the energies of the five 5d levels of Ce3+ and the crystalline environment. Good agreement between predicted and observed average energy of the 5d configuration is demonstrated. In addition values for the bandgap of the host materials, Stokes shifts and luminescence decay time data are presented.
97 citations
TL;DR: In this article, the centroid shift of the 5 d -configuration of oxide and fluoride compounds were analyzed with a model involving the correlated motion between 5 d −electron and ligand electrons.
62 citations
11 Feb 2003-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, photoelectron yields increase almost linearly with γ-ray energy but a small nonlinearity is observed around 40 keV, where the influence of intrinsic absorption and reflecting tape on the yields are discussed.
Abstract: Scintillation properties like photoelectron yield and light yield of Ce3+-doped YAlO3 and mixed Lux(RE)1−xAlO3 (RE=Y3+ and Gd3+) perovskite crystals are presented. The photoelectron yields increase almost linearly with γ-ray energy but a small non-linearity is observed around 40 keV. Scintillation and spectroscopic properties like UV or X-ray excited emission, laser excited emission, excitation and absorption spectra and photo- and scintillation decay of the different crystals are compared. The influence of intrinsic absorption and reflecting tape on the yields are discussed. Selected YAlO3:Ce showed the highest light yield of 25,000 phels/MeV and an energy resolution of 4.5% for 662 keV γ-radiation. The γ-ray linear absorption coefficient increases with Lu content and that of LuAlO3:Ce is almost 10 times higher than that of YAlO3:Ce.
55 citations
TL;DR: In this paper, the optical properties and scintillation mechanism in pure and Ce 31 -doped K2LaX5 and LaX3 have been determined under x-ray, gray, vacuum ultraviolet light, and synchrotron radiation excitation.
Abstract: The optical properties and scintillation mechanism in pure and Ce 31 -doped K2LaX5 and LaX3 have been determined under x-ray, g-ray, vacuum ultraviolet light, and synchrotron radiation excitation. Special attention is paid to the influence of anions X5Cl 2 ,B r 2 , and I 2 , and a comparison is made with properties of pure and Eu 21 -doped KX compounds. The energies of the 5d excited states of Ce 31 have been determined, and the total crystal field splitting and the centroid shift are discussed. An excitation across the band gap creates a combination of self-trapped exciton ~STE! and Ce 31 emission. These emissions are often anticorrelated when temperature or Ce 31 concentration is changed. Their ratio is related to the STE mobility and STE creation rate. Clear trends in the optical properties and scintillation mechanism are observed along the halide series.
50 citations
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National and Kapodistrian University of Athens1, University of the Mediterranean2, Paul Scherrer Institute3, CERN4, Royal Institute of Technology5, University of Liverpool6, Boston University7, DSM8, Aristotle University of Thessaloniki9, University of Coimbra10, University of Ljubljana11, Delft University of Technology12, University of Ioannina13, University of Fribourg14, Centre national de la recherche scientifique15
TL;DR: The CPLEAR experiment as discussed by the authors was devoted to the study of, and symmetries in the neutral-kaon system, and a variety of measurements allowed us to determine with high precision the parameters which describe the time evolution of the neutral kaons and their antiparticles, including decay amplitudes, and related symmetry properties.
45 citations
TL;DR: In this paper, the Compton coincidence technique (CCT) was used to measure the electron and photon response of an aluminum canned LaCl/sub 3/:10% Ce/sup 3+/ crystal.
Abstract: The electron and photon response of an aluminum canned LaCl/sub 3/:10% Ce/sup 3+/ crystal were measured using the Compton coincidence technique (CCT). The LaCl/sub 3/:10% Ce/sup 3+/ electron response increases from 7 keV to 30 keV by about 10%. Above 30 keV, the electron response levels, i.e., it is flat within 5%. The Monte Carlo N particle code (MCNP4C) was used in the photon response calculation. The calculated theoretical photon response is in good agreement with the measured photon response. An energy resolution (full width at half maximum over the peak position) of 4.2/spl plusmn/0.5% was observed for the 662 keV full absorption peak. The energy resolution as function of photon energy exhibits a linear relationship with the inverse square root of the energy. The step like curves of NaI(Tl) with a semi plateau in the energy range between 100 and 500 keV have not been observed for LaCl/sub 3/:10% Ce/sup 3+/.
39 citations
TL;DR: In this article, a mechanism involving valence hole trapping and energy transfer from excitonic states to Pr3+ is proposed to explain this, which shows a shift of 1.52 eV between 5d states of the ions.
Abstract: SrAl12O19:Pr phosphors have been investigated under ultraviolet/vacuum ultraviolet (5–20 eV) synchrotron radiation at room and near liquid He temperatures. The excitation of 1S 0 →1I 6 and 3P 0 →3H 4 emission of Pr3+ in SrAl12O19 occurs in a 1 eV wide region originating from the interconfiguration 4f2 → 4f5d transitions with threshold (onset of the transitions) at 6.0 eV at room temperature and at 6.15 eV at 14 K. A comparison of the excitation spectra of Pr3+ and known data for Ce3+ in SrAl12O19 reveals a shift of 1.52 eV between 5d states of the ions. The next threshold near 7.5 eV corresponds to the transitions from valence to conduction band. The luminescence from the 3P 0 level is excited efficiently at low temperature while 1S 0 luminescence is absent under band-to-band excitation. To explain this, a mechanism involving valence hole trapping and energy transfer from excitonic states to Pr3+ is proposed. At excitation near the maximum of 4f2 → 4f5d transitions (6.4 eV), the 1S 0 →1I 6 luminescence exhibits exponential decay with constant τ = 330 ± 10 ns at 300 K and τ ≈ 400 ns at 14 K. At pre-threshold excitation (E < 6.0 eV) a fast component τ ≈ 10 ns originating from excitonic emission prevails.
31 citations
TL;DR: In this article, an emission at 281 nm with a 10.5 ns single exponential decay and a highly selective, narrow excitation region between 202 and 211 nm has been observed for ${\mathrm{Ce}}^{3+}$ doped in {Ce}
Abstract: An emission at 281 nm with a 10.5 ns single exponential decay and a highly selective, narrow excitation region between 202 and 211 nm has been observed for ${\mathrm{Ce}}^{3+}$ doped in ${\mathrm{Cs}}_{3}{\mathrm{LuCl}}_{6}.$ Wavelengths between 50--200 nm and longer than 215 nm have zero excitation efficiency. Excitation and emission spectra of ${\mathrm{Cs}}_{3}{\mathrm{LuCl}}_{6}:{\mathrm{Ce}}^{3+}$ in the 10--300 K temperature range were excited by pulsed synchrotron radiation between 50--335 nm. In addition to this new emission, the conventional ${\mathrm{Ce}}^{3+}$ doublet emission from the lowest $5d$ level to the ${}^{2}{F}_{5/2}$ (368 nm) and ${}^{2}{F}_{7/2}$ levels (400 nm) of the ${4f}^{1}$ configuration is observed. Autoionization of the $5d$ electron to conduction band states followed by the direct transition to the ${}^{2}F$ levels is proposed to explain the 281 nm emission and to explain the absence of emission under across bandgap excitation.
TL;DR: In this article, the scintillation properties of LaCl3 crystals, doped with Ce3+ concentrations of 0.57, 1.0, 2.0 and 10%, were studied under x-ray and γ-quanta excitation at various temperatures.
Abstract: The scintillation properties of LaCl3 crystals, doped with Ce3+ concentrations of 0.57, 1.0, 2.0, 4.0, and 10%, are studied under x-ray and γ-quanta excitation at various temperatures. Under x-ray excitation, characteristic doublet Ce3+ emission is observed with a maximum at 3.7 eV. Also self-trapped exciton (STE) emission is observed with a maximum near 3.1 eV. The contribution of STE luminescence to the total light yield decreases with increasing Ce concentration. For LaCl3:0.57%Ce3+, the contribution is 33%, whereas for LaCl3:10%Ce3+ it is 4%. The total light yield of the Ce3+-doped samples ranges from 38 000 photons per megaelectronvolt (ph MeV−1) of absorbed γ-ray energy to 47 000(ph MeV−1) for LaCl3:0.57%Ce3+ and LaCl3:10%Ce3+, respectively. A model is proposed to explain the energy transfer from the host lattice to the Ce3+ ions. At these Ce concentrations, energy transfer by STE diffusion is held to be dominant.
01 Jan 2003-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the optical and scintillation properties of pure LuCl3, LiCl3:0.45, 2, 4, 10% Ce3+, LuBr3: 0.021%, 0.46, 0.76, 2.5%, and 8% Ce3+ are studied under X-ray and γ-ray excitation.
Abstract: The optical and scintillation properties of pure LuCl3, LuCl3:0.45%, 2%, 4%, 10% Ce3+, LuBr3:0.021%, 0.46%, 0.76%, 2.5%, and 8% Ce3+ are studied under X-ray and γ-ray excitation. The highest light yield of 29,000±3000 photons per MeV (ph/MeV) of absorbed γ-ray energy was measured for LuBr3:0.021% Ce3+. Energy resolutions obtained with a Hamamatsu R1791 photomultiplier tube (PMT) range from 6.0±0.5% to 18±2% for LuBr3:8% Ce3+ and LuCl3:0.45% Ce3+, respectively. For both LuCl3:Ce3+ and LuBr3:Ce3+, binary electron–hole diffusion was proposed as the dominant scintillation mechanism. At lower irradiation temperatures, VK diffusion is probably more important in the case of LuBr3:Ce3+.
TL;DR: In this article, an overview of the photon cascade emission (PCE) process for different Pr3+-doped materials is given and the factors which determine the amount of emission originating from the second (3 P 0 / 1 D 2 → 2S+1 L J ) quantum cutting step are discussed.
TL;DR: An emission at 281 nm with a 105 ns single exponential decay and a highly selective, narrow excitation region between 202 and 211 nm has been observed for ${\mathrm{Ce}}^{3+}$ doped in {Ce}µ,LuClµ,6}.
Abstract: An emission at 281 nm with a 105 ns single exponential decay and a highly selective, narrow excitation region between 202 and 211 nm has been observed for ${\mathrm{Ce}}^{3+}$ doped in ${\mathrm{Cs}}_{3}{\mathrm{LuCl}}_{6}$ Wavelengths between 50--200 nm and longer than 215 nm have zero excitation efficiency Excitation and emission spectra of ${\mathrm{Cs}}_{3}{\mathrm{LuCl}}_{6}:{\mathrm{Ce}}^{3+}$ in the 10--300 K temperature range were excited by pulsed synchrotron radiation between 50--335 nm In addition to this new emission, the conventional ${\mathrm{Ce}}^{3+}$ doublet emission from the lowest $5d$ level to the ${}^{2}{F}_{5/2}$ (368 nm) and ${}^{2}{F}_{7/2}$ levels (400 nm) of the ${4f}^{1}$ configuration is observed Autoionization of the $5d$ electron to conduction band states followed by the direct transition to the ${}^{2}F$ levels is proposed to explain the 281 nm emission and to explain the absence of emission under across bandgap excitation
21 Aug 2003-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a new type of mini multi-element Tissue-Equivalent Proportional Counter (TEPC) has been designed and constructed by employing a Gas Electron Multiplier.
Abstract: By employing a Gas Electron Multiplier a new type of mini multi-element Tissue-Equivalent Proportional Counter (TEPC) has been designed and constructed. In this paper, we describe the design of this novel counter. The first pulse height measurements with this counter for both methane- and propane-based Tissue Equivalent gases are presented. These results show promising properties for application of this novel type TEPC in microdosimetric measurements.
01 Nov 2003-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a gaseous scintillation detector consisting of a Ar+CF4 filled GEM and a CCD camera has been investigated for the application as a position sensitive dosimeter in proton-beam radiation therapy.
Abstract: A gaseous scintillation detector consisting of a Ar+CF4 filled GEM and a CCD camera has been investigated for the application as a position sensitive dosimeter in proton-beam radiation therapy. The light yield has been measured as a function of the CF4 concentration, operating voltage, beam intensity and beam energy. In conditions where the gas gain decreases due to a lower electric field, an increase of the amount of light per secondary electron is observed. The mixture of Ar+5% CF4 has the largest light output in absolute sense as well as per secondary electron. The scintillating Gas Electron Multiplier emits >1.5 times more light than needed and the signal-quenching in the Bragg peak which occurs in solid scintillators is reduced by a factor 4.
21 Jun 2003-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the operation of two different Gas Electron Multiplier (GEM) structures in both methane and propane based Tissue-Equivalent (TE) gases at different pressures varying from 0.1 to 1.
Abstract: We have studied the operation of two different Gas Electron Multiplier (GEM) structures in both methane and propane based Tissue-Equivalent (TE) gases at different pressures varying from 0.1 to 1 atm. This work was motivated to explore the possibility of using a GEM for a new type of Tissue Equivalent Proportional Counter. In methane based TE gas, a maximum safe GEM gain of 1.5×10 3 has been reached while in propane based TE gas this is 6×10 3 . These maxima have been reached at different gas pressures depending on GEM structure and TE gas. Furthermore, we observed a decrease of the GEM gain in time before it becomes stable. Charge up/polarisation effects can explain this.
TL;DR: In this article, three materials Ce:Li 2 CaSiO 4, Ce:CaBPO 5, and LiCaPO 4 were synthesized as polycrystalline samples for scintillation application in neutron detection.
TL;DR: In this article, the luminescence properties of Ce3+ activated strontium haloborates with and without K+ or Na+ co-doping have been studied under optical and x-ray excitation.
Abstract: The luminescence properties of Ce3+ activated strontium haloborates with and without K+ or Na+ co-doping have been studied under optical and x-ray excitation. Three types of Ce3+ emission centre have been found as the result of different methods of charge compensation in non-co-doped samples. In the co-doped compounds only one type of Ce3+ emission centre has been observed. The influence of Ce3+ concentration, anion type and co-doping ion on thermoluminescence (TL) has been analysed. The TL glow curves of all the studied materials contain two peaks. The emission corresponding to the low temperature peak is associated with charge uncompensated Ce3+ centres in non-co-doped compounds. The emission of the high temperature peak represents the superposition of both charge compensated and uncompensated Ce3+ centres. The emission corresponding to both TL peaks in co-doped samples originates from one type of Ce3+ centre.
TL;DR: In this paper, the problem of optimization of both the number of energies and the energies themselves for application in the oil industry, where oil, water, and gas mixtures flow through pipes is addressed.
Abstract: When using X-rays in multiphase flow meters operating according to the DEGRA principle, the number of energy values as well as the X-ray energies can in principle be chosen freely. This report assesses the problem of optimization of both the number of energies and the energies themselves for application in the oil industry, where oil, water, and gas mixtures flow through pipes.
TL;DR: In this paper, the first experimental results for the ddμ molecule formation rate λddμ in the temperature range 400-790 K with a deuterium density of about 0.5 and 0.8 of the liquid hydrogen density are presented.
Abstract: Muon catalyzed fusion (MCF) in deuterium was studied by the MCF collaboration on the Joint Institute for Nuclear Research Phasotron. The measurements were carried out with a high-pressure deuterium target in the temperature range 85–790 K at densities of about 0.5 and 0.8 of the liquid hydrogen density. The first experimental results for the ddμ molecule formation rate λddμ in the temperature range 400–790 K with a deuterium density of about 0.5 of the liquid hydrogen density are presented.
TL;DR: In this paper, the ESR spectra of Ce3+ ions in polycrystalline Sr2B5O9Br were studied, and the two crystallographic positions of the C3+ ion in this compound were identified on the basis of the data obtained.
Abstract: ESR spectra of Ce3+ ions in polycrystalline Sr2B5O9Br were studied, and the two crystallographic positions of the Ce3+ ion in this compound were identified on the basis of the data obtained. The ESR spectrum of Ce3+ ions with local charge compensation contains a broad line indicating the existence of several types of charge compensation. ESR spectra of Ce3+ ions in samples activated additionally by K+ ions are similar to those of the regular Ce3+ centers, which indicates that the effect of the univalent cation on Ce3+ is negligible.
TL;DR: In this paper, the electronic and spatial structures of the La impurity in BaF2 are investigated using the ab initio method of linear combinations of atomic orbitals based on the Hartree-Fock approximation in the supercell model.
Abstract: The electronic and spatial structures of the La impurity in BaF2 are investigated using the ab initio method of linear combinations of atomic orbitals based on the Hartree-Fock approximation in the supercell model. Calculations are performed using the CRYSTAL-98 software package. Possible models of defects are discussed. The MOLSTAT computer code is employed to estimate the energies of formation of defects and their parameters. The influence of defects on the BaF2 band structure is analyzed.
TL;DR: In this article, the authors describe the design of a geometry for the generation of X-rays to measure the relative amounts of oil, water, and gas in a flow, and conclude that with an X-ray tube power in the order of only /spl sim/ 2.5 W, successful multiple energy Xray absorption analysis should be possible.
Abstract: This paper describes the design of a geometry for the generation of X-rays to measure the relative amounts of oil, water, and gas in a flow. The measurement principle is based on the attenuation of X-rays in the mixture. The X-rays are generated by fluorescence in slanted foils placed in front of an end-window X-ray tube. EGS4 Monte Carlo simulations have been used to determine an optimum geometry. We conclude that with an X-ray tube power in the order of only /spl sim/ 2.5 W, successful multiple energy X-ray absorption analysis should be possible.
TL;DR: In this paper, a comparative study of photostimulated luminescence (PSL) kinetics was performed for halogen-containing borates and commercial gadolinium-containing neutron SPs.
Abstract: The main requirements on neutron detectors based on storage phosphors (SPs) are formulated. It is shown that commercial gadolinium-containing neutron SPs (Gd-SPs) based on mixtures of BaFBr:Eu2+ with Gd2O3 (a neutron converter) do not possess optimum neutron characteristics because of a high sensitivity to gamma radiation. A comparative study of photostimulated luminescence (PSL) kinetics was performed for samples of halogen-containing borates Sr2B5O9Br(Cl) and Ca2B5O9Br(Cl) activated with Ce3+ ions and of the commercial Gd-SPs upon neutron and gamma irradiation. The results suggest that the PSL characteristics of the above borates with 100% content of 10B must be similar to those of Gd-SPs. Use of the halogen borates as SPs offers an advantage to Gd-SPs, because the former neutron detectors are less sensitive to gamma radiation.