This paper presents new developments in inorganic scintillators widely used for radiation detection. It addresses major emerging research topics outlining current needs for applications and material ...sciences issues with the overall aim to provide an up-to-date picture of the field. While the traditional forms of scintillators have been crystals and ceramics, new research on films, nanoparticles, and microstructured materials is discussed as these material forms can bring new functionality and therefore find applications in radiation detection. The last part of the contribution reports on the very recent evolutions of the most advanced theories, methods, and analyses to describe the scintillation mechanisms.
Alkali-earth halide scintillators have received much attention in the last 2 years due to their high luminosity close to the theoretical limit. We present a summary of the knowledge acquired to date ...that is relevant to scintillation applications. Progress achieved in the synthesis, growth and performance of these scintillators, specially the Ba mixed halides (such as BaBrI and BaBrCl) and the family of compounds made by combining Cs and Ba halides in various stoichiometries are presented.
► We have reviewed and further studied the formation of ternary compounds in Ba and Sr halides. ► We present the scintillation properties of 6 of Ba mixed halides activated with Eu. ► We present 10 ternary compounds of the complex systems (Ba or Sr)-Cs halides. ► We present the scintillation properties of 8 of them activated with Eu. ► We confirm CsBa2I5:Eu and BaBrI:Eu are the best scintillator of these classes of compounds.
The quest for the ideal inorganic scintillator Derenzo, S.E.; Weber, M.J.; Bourret-Courchesne, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2003, Letnik:
505, Številka:
1-2
Journal Article
Recenzirano
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.
A systematic study of the structure and scintillation properties of La elpasolites and related compositions with the formula Cs2ALa1−yCeyX6 (where A=Cs, Na; X=Cl, Br, I) is reported. The compounds ...were determined to crystallize in a variety of crystal structures. Two of the compounds studied are cubic and their structures match a prediction derived from a composition-related tolerance factor. The cubic structure was not obtained with the iodides. Upon optical and X-ray excitation, the samples show the characteristic Ce3+ emission. Depending on the host, the optimal Ce concentration varied between 0.1 and 15%. The luminosity and energy resolution were measured on 4 single crystals with the following results: Cs2NaLaCl6:4% Ce luminosity of 26,400ph/MeV, energy resolution 4.4%; Cs3LaCl6:8% Ce luminosity of 16,000ph/MeV, energy resolution 8.6%; Cs2NaLaBr6:4% Ce luminosity of 46,000ph/MeV, energy resolution 3.9%; Cs3LaBr6:15% Ce luminosity of 32,500ph/MeV, energy resolution 4.9%. Single crystals of the iodide analogs could not be obtained by the Bridgman technique due to phase separation. Polycrystalline forms of these compounds, obtained by quenching from the melt, are scintillators.
•Systematic study of structure and scintillation of La elpasolites and related compositions.•New structures for Cs2NaLaCl6, Cs2NaLaBr6, Cs3LaBr6, and Cs3LaI6.•New scintillators-Ce3+ activated Cs3LaCl6, Cs2NaLaI6 and Cs3LaI6.•Significantly improved scintillation in Cs2NaLaCl6, Cs2NaLaBr6 and Cs3LaBr6.
We performed resistance measurements on Fe1+δ−xCuxTe with xEDX 0.06 in the presence of in-plane applied magnetic fields, revealing a resistance anisotropy that can be induced at a temperature far ...below the structural and magnetic zero-field transition temperatures. The observed resistance anisotropy strongly depends on the field orientation with respect to the crystallographic axes, as well as on the field-cooling history. Our results imply a correlation between the observed features and the low-temperature magnetic order. Hysteresis in the angle-dependence indicates a strong pinning of the magnetic order within a temperature range that varies with the Cu content. The resistance anisotropy vanishes at different temperatures depending on whether an external magnetic field or a remnant field is present: the closing temperature is higher in the presence of an external field. For xEDX=0.06 the resistance anisotropy closes above the structural transition, at the same temperature at which the zero-field short-range magnetic order disappears and the sample becomes paramagnetic. Thus we suggest that under an external magnetic field the resistance anisotropy mirrors the magnetic order parameter. We discuss similarities to nematic order observed in other iron pnictide materials.
We investigate the effects of post-growth annealing on the structural and magnetic properties of BaFe2As2. Magnetic susceptibility measurements, which exhibit a signal corresponding to the magnetic ...phase transition, and high-resolution x-ray diffraction measurements, which directly probe the structural order parameter, show that annealing causes the ordering temperatures of both the phase transitions to increase, sharpen and converge. In the as grown sample, our measurements show two distinct transitions corresponding to structural and magnetic ordering, which are separated in temperature by approximately 1 K. After 46 days (d) of annealing at 700 °C, the two become concurrent in temperature. These measurements demonstrate that the structural phase transition is second-order like when the magnetic and structural phase transitions are separated in temperature, and first-order like when the two phase transition temperatures coincide. This observation indicates that annealing causes the system to cross a hitherto undiscovered tricritical point. In addition, x-ray diffraction measurements show that the c-axis lattice parameter increases with annealing up to 30 d, but remains constant for longer annealing times. Comparisons of BaFe2As2 to SrFe2As2 are made when possible.
We have previously reported the scintillation properties of CsBa2I5 activated with Eu2+, which exhibits excellent behavior 1,2. The presence of Cs in the lattice makes CsBa2I5 a good candidate for ...activation with monovalent ions. We grew single crystals of CsBa2I5 with monovalent ions Tl, Na and In as activators. We performed a series of luminescence and scintillation measurements, including pulse height measurements using two different photosensors, on these crystals. We show not only that the monovalent ions are suitable activators in the chosen host lattice but also that the system has light yields between 33,000 and 40,000ph/MeV, lower self-absorption than observed in Eu doped samples and excellent proportionality. The measured energy resolution on our initial samples of 7.1% FWHM for 662keV gamma rays using avalanche photodiodes is very promising.
•CsBa2I5 doped with monovalent ions Tl, Na and In as activators.•Luminescence and scintillation measurements, including pulse height measurements using two different photosensors.•Light yields between 33,000 and 40,000ph/MeV and lower self-absorption than observed in Eu doped samples.•Energy resolution of 7.1% FWHM for 662keV gamma rays using avalanche photodiodes is very promising.
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