Charge carrier and exciton dynamics in LaBr{sub 3}:Ce{sup 3+} scintillators: Experiment and model
Abstract
The scintillation yield and decay time of LaBr{sub 3} doped with 0.2%, 0.5%, and 5% cerium were studied between 80 K and 600 K. LaBr{sub 3}:5%Ce{sup 3+} on a photomultiplier tube shows at 300 K a very high scintillation yield of 22 800 photoelectrons per MeV (64 000 photons per MeV) with a decay time of 16 ns. At 600 K the yield decreases by {approx_equal}15%. The scintillation yield of LaBr{sub 3}:0.2%Ce{sup 3+} is 19 800 photoelectrons per MeV (56 000 photons per MeV) at 300 K with a decrease by {approx_equal}50% at 600 K and a main scintillation decay time around 30 ns. The appearance of slow components in the Ce emission indicates a relatively slow energy transfer from the host crystal to Ce. The presence or absence of slow components depends on both concentration and temperature. The results are analyzed and interpreted with a model that comprises prompt charge carrier trapping by Ce and delayed excitation of Ce by means of thermally activated transport of self-trapped exciton defects. The results of the study provide detailed information on the scintillation mechanism. Besides presenting experimental data, the different energy transfer processes are quantified.
- Authors:
- Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands)
- Publication Date:
- OSTI Identifier:
- 20951413
- Resource Type:
- Journal Article
- Resource Relation:
- Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 75; Journal Issue: 18; Other Information: DOI: 10.1103/PhysRevB.75.184302; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; CERIUM; CERIUM IONS; CHARGE CARRIERS; DOPED MATERIALS; ENERGY TRANSFER; EXCITONS; EXPERIMENTAL DATA; GAMMA DETECTION; LANTHANUM BROMIDES; PHOTOMULTIPLIERS; PHOTONS; SCINTILLATIONS; SOLID SCINTILLATION DETECTORS; TEMPERATURE DEPENDENCE; YIELDS
Citation Formats
Bizarri, G., and Dorenbos, P. Charge carrier and exciton dynamics in LaBr{sub 3}:Ce{sup 3+} scintillators: Experiment and model. United States: N. p., 2007.
Web. doi:10.1103/PHYSREVB.75.184302.
Bizarri, G., & Dorenbos, P. Charge carrier and exciton dynamics in LaBr{sub 3}:Ce{sup 3+} scintillators: Experiment and model. United States. doi:10.1103/PHYSREVB.75.184302.
Bizarri, G., and Dorenbos, P. Tue .
"Charge carrier and exciton dynamics in LaBr{sub 3}:Ce{sup 3+} scintillators: Experiment and model". United States.
doi:10.1103/PHYSREVB.75.184302.
@article{osti_20951413,
title = {Charge carrier and exciton dynamics in LaBr{sub 3}:Ce{sup 3+} scintillators: Experiment and model},
author = {Bizarri, G. and Dorenbos, P.},
abstractNote = {The scintillation yield and decay time of LaBr{sub 3} doped with 0.2%, 0.5%, and 5% cerium were studied between 80 K and 600 K. LaBr{sub 3}:5%Ce{sup 3+} on a photomultiplier tube shows at 300 K a very high scintillation yield of 22 800 photoelectrons per MeV (64 000 photons per MeV) with a decay time of 16 ns. At 600 K the yield decreases by {approx_equal}15%. The scintillation yield of LaBr{sub 3}:0.2%Ce{sup 3+} is 19 800 photoelectrons per MeV (56 000 photons per MeV) at 300 K with a decrease by {approx_equal}50% at 600 K and a main scintillation decay time around 30 ns. The appearance of slow components in the Ce emission indicates a relatively slow energy transfer from the host crystal to Ce. The presence or absence of slow components depends on both concentration and temperature. The results are analyzed and interpreted with a model that comprises prompt charge carrier trapping by Ce and delayed excitation of Ce by means of thermally activated transport of self-trapped exciton defects. The results of the study provide detailed information on the scintillation mechanism. Besides presenting experimental data, the different energy transfer processes are quantified.},
doi = {10.1103/PHYSREVB.75.184302},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 18,
volume = 75,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
-
The scintillation response of LaBr{sub 3}:Ce scintillation crystals was studied as function of temperature and Ce concentration with synchrotron X-rays between 9 keV and 100 keV. The results were analyzed using the theory of carrier transport in wide band gap semiconductors to gain new insights into charge carrier generation, diffusion, and capture mechanisms. Their influence on the efficiency of energy transfer and conversion from X-ray or γ-ray photon to optical photons and therefore on the energy resolution of lanthanum halide scintillators was studied. From this, we will propose that scattering of carriers by both the lattice phonons and by ionizedmore »
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Ce{sup 3+} activated LaBr{sub 3-x}I{sub x}: High-light-yield and fast-response mixed halide scintillators
Here, we report the scintillation properties of LaBr{sub 3-x}I{sub x}:5%Ce{sup 3+} with four different compositions of x, i.e., x=0.75, 1.5, 2, and 2.25. Radioluminescence spectra reveal a shift of the emission wavelength with the LaBr{sub 3} to LaI{sub 3} ratio. LaBr{sub 1.5}I{sub 1.5}:5%Ce{sup 3+} shows the highest scintillation light yield of 58 000 photons/MeV, whereas LaBr{sub 0.75}I{sub 2.25}:5%Ce{sup 3+} shows the fastest scintillation decay time of 12 ns under 662 keV {gamma}-ray excitation. This decay time is faster than that of 16 ns in LaBr{sub 3}:Ce{sup 3+}. The temperature dependence of radioluminescence spectra is presented. The structures and lattice parametersmore » -
Response of LaBr{sub 3}(Ce) scintillators to 2.5 MeV fusion neutrons
Measurements of the response of LaBr{sub 3}(Ce) to 2.5 MeV neutrons have been carried out at the Frascati Neutron Generator and at tokamak facilities with deuterium plasmas. The observed spectrum has been interpreted by means of a Monte Carlo model. It is found that the main contributor to the measured response is neutron inelastic scattering on {sup 79}Br, {sup 81}Br, and {sup 139}La. An extrapolation of the count rate response to 14 MeV neutrons from deuterium-tritium plasmas is also presented. The results are of relevance for the design of γ-ray diagnostics of fusion burning plasmas. -
A comparative study of LaBr{sub 3}(Ce{sup 3+}) and CeBr{sub 3} based gamma-ray spectrometers for planetary remote sensing applications
The recent availability of large volume cerium bromide crystals raises the possibility of substantially improving gamma-ray spectrometer limiting flux sensitivities over current systems based on the lanthanum tri-halides, e.g., lanthanum bromide and lanthanum chloride, especially for remote sensing, low-level counting applications or any type of measurement characterized by poor signal to noise ratios. The Russian Space Research Institute has developed and manufactured a highly sensitive gamma-ray spectrometer for remote sensing observations of the planet Mercury from the Mercury Polar Orbiter (MPO), which forms part of ESA’s BepiColombo mission. The Flight Model (FM) gamma-ray spectrometer is based on a 3-in. singlemore » -
Improvement of {gamma}-ray energy resolution of LaBr{sub 3}:Ce{sup 3+} scintillation detectors by Sr{sup 2+} and Ca{sup 2+} co-doping
Commercially available LaBr{sub 3}:5% Ce{sup 3+} scintillators show with photomultiplier tube readout about 2.7% energy resolution for the detection of 662 keV {gamma}-rays. Here we will show that by co-doping LaBr{sub 3}:Ce{sup 3+} with Sr{sup 2+} or Ca{sup 2+} the resolution is improved to 2.0%. Such an improvement is attributed to a strong reduction of the scintillation light losses that are due to radiationless recombination of free electrons and holes during the earliest stages (1-10 ps) inside the high free charge carrier density parts of the ionization track.