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Title: Performance of new ceramic scintillators for gamma and x-ray detection

Abstract

Ceramic materials show significant promise for the production of reasonably priced, large-size scintillators. Ceramics have recently received a great deal of attention in the field of materials for laser applications, and the technology for fabricating high-optical-quality polycrystalline ceramics of cubic materials has been well developed. The formation of transparent ceramics of non-cubic materials is, however, much more difficult as a result of birefringence effects in differently oriented grains. Here, we will describe the performance of a few new ceramics developed for the detection of gamma- and x-ray radiation. Results are presented for ceramic analogs of three crystalline materials - cubic Lu2O3, and non-cubic LaBr3, and Lu2SiO5 or LSO (hexagonal, and monoclinic structures, respectively). The impact of various sintering, hot-pressing and post-formation annealing procedures on the light yield, transparency, and other parameters, will be discussed. The study of LaBr3:Ce shows that fairly translucent ceramics of rare-earth halides can be fabricated and they can reach relatively high light yield values. Despite the fact that no evidence for texturing has been found in our LSO:Ce ceramic microstructures, the material demonstrates a surprisingly high level of translucency or transparency. While the scintillation of LSO:Ce ceramic reaches a light yield level of about 86 %more » of that of a good LSO:Ce single crystal, its decay time is even faster, and the long term afterglow is lower than in LSO single crystals.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [2];  [2];  [3]
  1. ORNL
  2. ALEM Associates, Boston
  3. Radiation Monitoring Devices, Watertown, MA
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
963400
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: SPIE, San Diego, CA, USA, 20070826, 20070830
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; PHOSPHORS; CERAMICS; PERFORMANCE TESTING; GAMMA DETECTION; X-RAY DETECTION; LUTETIUM OXIDES; LANTHANUM BROMIDES; LUTETIUM SILICATES; HEAT TREATMENTS; scintillators; scintillation; ceramics; LSO:Ce; LaBr3:Ce; Lu2O3:Eu; luminescence; afterglow

Citation Formats

Wisniewski, Dariusz J, Boatner, Lynn A, Neal, John S, Jellison Jr, Gerald Earle, Ramey, Joanne Oxendine, North, Andrea L, Wisniewska, Monika, Lempicki, Aleksander, Brecher, Charlie, and Glodo, J. Performance of new ceramic scintillators for gamma and x-ray detection. United States: N. p., 2007. Web.
Wisniewski, Dariusz J, Boatner, Lynn A, Neal, John S, Jellison Jr, Gerald Earle, Ramey, Joanne Oxendine, North, Andrea L, Wisniewska, Monika, Lempicki, Aleksander, Brecher, Charlie, & Glodo, J. Performance of new ceramic scintillators for gamma and x-ray detection. United States.
Wisniewski, Dariusz J, Boatner, Lynn A, Neal, John S, Jellison Jr, Gerald Earle, Ramey, Joanne Oxendine, North, Andrea L, Wisniewska, Monika, Lempicki, Aleksander, Brecher, Charlie, and Glodo, J. Mon . "Performance of new ceramic scintillators for gamma and x-ray detection". United States. doi:.
@article{osti_963400,
title = {Performance of new ceramic scintillators for gamma and x-ray detection},
author = {Wisniewski, Dariusz J and Boatner, Lynn A and Neal, John S and Jellison Jr, Gerald Earle and Ramey, Joanne Oxendine and North, Andrea L and Wisniewska, Monika and Lempicki, Aleksander and Brecher, Charlie and Glodo, J.},
abstractNote = {Ceramic materials show significant promise for the production of reasonably priced, large-size scintillators. Ceramics have recently received a great deal of attention in the field of materials for laser applications, and the technology for fabricating high-optical-quality polycrystalline ceramics of cubic materials has been well developed. The formation of transparent ceramics of non-cubic materials is, however, much more difficult as a result of birefringence effects in differently oriented grains. Here, we will describe the performance of a few new ceramics developed for the detection of gamma- and x-ray radiation. Results are presented for ceramic analogs of three crystalline materials - cubic Lu2O3, and non-cubic LaBr3, and Lu2SiO5 or LSO (hexagonal, and monoclinic structures, respectively). The impact of various sintering, hot-pressing and post-formation annealing procedures on the light yield, transparency, and other parameters, will be discussed. The study of LaBr3:Ce shows that fairly translucent ceramics of rare-earth halides can be fabricated and they can reach relatively high light yield values. Despite the fact that no evidence for texturing has been found in our LSO:Ce ceramic microstructures, the material demonstrates a surprisingly high level of translucency or transparency. While the scintillation of LSO:Ce ceramic reaches a light yield level of about 86 % of that of a good LSO:Ce single crystal, its decay time is even faster, and the long term afterglow is lower than in LSO single crystals.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

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  • We present recent results from an ongoing search for inorganic scintillators for gamma ray detection in which we measure the scintillation properties (luminous efficiency, decay time, and emission wavelength) of powdered samples excited by brief x-ray pulses. Recent promising candidates include cerium doped lutetium borate (LuBO{sub 3}) and the lutetium double phosphates K{sub 3}Lu(PO{sub 4}){sub 2} and Rb{sub 3}Lu(PO{sub 4}){sub 2}, which have luminous intensities above 25,000 photons/MeV. In order to find scintillators that are compatible with silicon photodetectors, we have tested over 1,100 samples using a photomultiplier tube with a GaAs:Cs photocathode, which is sensitive to emissions from 200-950more » nm. While many samples exhibited strong emissions in the 600-900 nm range, all had decay times that were larger than 10 {mu}s.« less
  • When activated with an appropriate rare-earth ion (e.g., Ce or Nd), rare-earth orthophosphates of the form REPO4 (where RE = a rare-earth cation) and alkali rare-earth double phosphates of the form A{sub 3}RE(PO{sub 4}){sub 2} (where A = K, Rb, or Cs) are characterized by light yields and decay times that make these materials of interest for radiation-detection applications. Crystals of the compound Rb{sub 3}Lu(PO{sub 4}){sub 2} when activated with {approx}0.1 mol % Ce exhibit a light yield that is {approx}250% that of BGO with a decay time on the order of {approx}40 nsec. The cerium-activated rare-earth orthophosphate LuPO{sub 4}:Cemore » is also characterized by a high light yield and a relatively fast decay time of {approx}25 nsec. Additionally, the rare-earth orthophosphates are extremely chemically, physically, and thermally durable hosts that recover easily from radiation damage effects. The properties of the rare-earth orthophosphates and double phosphates that pertain to their use as X- and gamma-ray detectors are reviewed. This review includes information related to the use of Nd-doped LuPO{sub 4} as a scintillator with a sufficiently energetic, short-wavelength output ({lambda} = 90 nm) so that it can be used in conjunction with appropriately activated proportional counters. Information is presented on the details of the synthesis, structure, and luminescence properties of lanthanide double phosphates that, when activated with cerium, are efficient scintillators with output wavelengths that are sufficiently long to be well matched to the response of silicon photodiode detectors.« less
  • This project uses advanced ceramic processes to fabricate large, optical-quality, polycrystalline lanthanum halide scintillators to replace small single crystals produced by the conventional Bridgman growth method. The new approach not only removes the size constraint imposed by the growth method, but also offers the potential advantages of both reducing manufacturing cost and increasing production rate. The project goal is to fabricate dense lanthanum halide ceramics with a preferred crystal orientation by applying texture engineering and solid-state conversion to reduce the thermal mechanical stress in the ceramic and minimize scintillation light scattering at grain boundaries. Ultimately, this method could deliver themore » sought-after high sensitivity and <3% energy resolution at 662 keV of lanthanum halide scintillators and unleash their full potential for advanced gamma ray detection, enabling rapid identification of radioactive materials in a variety of practical applications. This report documents processing details from powder synthesis, seed particle growth, to final densification and texture development of cerium doped lanthanum bromide (LaBr{sub 3}:Ce{sup +3}) ceramics. This investigation demonstrated that: (1) A rapid, flexible, cost efficient synthesis method of anhydrous lanthanum halides and their solid solutions was developed. Several batches of ultrafine LaBr{sub 3}:Ce{sup +3} powder, free of oxyhalide, were produced by a rigorously controlled process. (2) Micron size ({approx} 5 {micro}m), platelet shape LaBr{sub 3} seed particles of high purity can be synthesized by a vapor phase transport process. (3) High aspect-ratio seed particles can be effectively aligned in the shear direction in the ceramic matrix, using a rotational shear-forming process. (4) Small size, highly translucent LaBr{sub 3} (0.25-inch diameter, 0.08-inch thick) samples were successfully fabricated by the equal channel angular consolidation process. (5) Large size, high density, translucent LaBr{sub 3} ceramics samples (3-inch diameter, > 1/8-inch thick) were fabricated by hot pressing, demonstrating the superior manufacturability of the ceramic approach over single crystal growth methods in terms of size capability and cost. (6) Despite all these advances, evidence has shown that LaBr{sub 3} is thermally unstable at temperatures required for the densification process. This is particularly true for material near the surface where lattice defects and color centers can be created as bromine becomes volatile at high temperatures. Consequently, after densification these samples made using chemically prepared ultrafine powders turned black. An additional thermal treatment in a flowing bromine condition proved able to reduce the darkness of the surface layer for these densified samples. These observations demonstrated that although finer ceramic powders are desirable for densification due to a stronger driving force from their large surface areas, the same desirable factor can lead to lattice defects and color centers when these powders are densified at higher temperatures where material near the surface becomes thermally unstable.« less
  • Cerium activated rare-earth tri- halides represent a well-known family of high performance inorganic rare-earth scintillators - including the high-light-yield, high-energy-resolution scintillator, cerium-doped lanthanum tribromide. These hygroscopic inorganic rare-earth halides are currently grown as single crystals from the melt - either by the Bridgman or Czochralski techniques slow and expensive processes that are frequently characterized by severe cracking of the material due to anisotropic thermal stresses and cleavage effects. We have recently discovered a new family of cerium-activated rare-earth metal organic scintillators consisting of tri-halide methanol adducts of cerium and lanthanum namely CeCl3(CH3OH)4 and LaBr3(CH3OH)4:Ce. These methanol-adduct scintillator materials can bemore » grown near room temperature from a methanol solution, and their high solubility is consistent with the application of the rapid solution growth methods that are currently used to grow very large single crystals of potassium dihydrogen phosphate. The structures of these new rare-earth metal-organic scintillating compounds were determined by single crystal x-ray refinements, and their scintillation response to both gamma rays and neutrons, as presented here, was characterized using different excitation sources. Tri-halide methanol-adduct crystals activated with trivalent cerium apparently represent the initial example of a solution-grown rare-earth metal-organic molecular scintillator that is applicable to gamma ray, x-ray, and fast neutron detection.« less