Lanthanum(III) bromide
Encyclopedia
Lanthanum bromide (LaBr3) is an inorganic halide salt of lanthanum
. When pure, it is a colorless white powder. The single crystals of LaBr3 are hexagonal crystals with melting point of 783°C. It is highly hygroscopic and water soluble. There are several hydrates, La3Br·X H2O, of the salt also known. It is often used as a source of lanthanum in chemical synthesis, and is being evaluated for use as a scintillation material in certain applications.
activated
lanthanum bromide is the recent inorganic scintillator
which has a combination of high light yield and the best energy resolution.
material have resulted in the development of cerium
activated
lanthanum bromide (LaBr3) detectors. LaBr3 was discovered in 2001 . These detectors offer improved energy resolution, fast emission and excellent temperature and linearity characteristics. Typical energy resolution at 662 keV is 3% as compared to sodium iodide
detectors at 7% . The improved resolution is due to a photoelectron yield of 160% that achieved with sodium iodide. Another advantage of LaBr3 is the nearly flat photo emission over a 70 °C temperature range (~1% change in light output).
Today LaBr3 detectors are offered with bialkali photomultiplier
tubes (PMT) that can be two inches in diameter and 10 or more inches long. However, miniature packaging can be obtained by the use of silicon drift detectors (SDD). These UV enhanced diodes provide excellent wavelength matching to the 380 nm emission of LaBr3. A recent paper presented at the 2005 IEEE Nuclear Science Symposium shows that the SDD has a higher quantum efficiency over the PMT . Moreover the SDD is not as sensitive to temperature and bias drift. The reported spectroscopy performance of the SDD configuration resulted in a 2.8% energy resolution at 662 keV for the detector sizes considered.
LaBr3 introduces an enhanced set of capabilities to a range of gamma spectroscopy
radioisotope detection and identification systems used in the homeland security
market. Isotope identification utilizes several techniques (known as algorithms) which rely on the detector’s ability to discriminate peaks. The improvements in resolution allow more accurate peak discrimination in ranges where isotopes often have many overlapping peaks. This leads to better isotope classification. Screening of all types (pedestrians, cargo, conveyor belts, shipping containers, vehicles, etc.) often requires accurate isotopic identification to differentiate concerning materials from non-concerning materials (medical isotopes in patients, naturally occurring radioactive materials, etc.) Heavy R&D and deployment of instruments utilizing LaBr3 is expected in the upcoming years. (List of companies who manufacture commercial off-the-shelf Radiation Isotope Identifiers for Homeland Security: Canberra Industries, ORTEC, Berkeley Nucleonics spectra sample and spectroscopy example, Polimaster )
Lanthanum
Lanthanum is a chemical element with the symbol La and atomic number 57.Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table and is the first element of the lanthanide series. It is found in some rare-earth minerals, usually in combination with cerium and...
. When pure, it is a colorless white powder. The single crystals of LaBr3 are hexagonal crystals with melting point of 783°C. It is highly hygroscopic and water soluble. There are several hydrates, La3Br·X H2O, of the salt also known. It is often used as a source of lanthanum in chemical synthesis, and is being evaluated for use as a scintillation material in certain applications.
Uses
CeriumCerium
Cerium is a chemical element with the symbol Ce and atomic number 58. It is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet . Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight...
activated
Activator (phosphor)
In phosphors and scintillators, the activator is the element added as dopant to the crystal of the material to create desired type of nonhomogeneities....
lanthanum bromide is the recent inorganic scintillator
Scintillator
A scintillator is a special material, which exhibits scintillation—the property of luminescence when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate, i.e., reemit the absorbed energy in the form of light...
which has a combination of high light yield and the best energy resolution.
Lanthanum bromide scintillation detector
Recent advances in scintillatorScintillator
A scintillator is a special material, which exhibits scintillation—the property of luminescence when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate, i.e., reemit the absorbed energy in the form of light...
material have resulted in the development of cerium
Cerium
Cerium is a chemical element with the symbol Ce and atomic number 58. It is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet . Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight...
activated
Activator (phosphor)
In phosphors and scintillators, the activator is the element added as dopant to the crystal of the material to create desired type of nonhomogeneities....
lanthanum bromide (LaBr3) detectors. LaBr3 was discovered in 2001 . These detectors offer improved energy resolution, fast emission and excellent temperature and linearity characteristics. Typical energy resolution at 662 keV is 3% as compared to sodium iodide
Sodium iodide
Sodium iodide is a white, crystalline salt with chemical formula NaI used in radiation detection, treatment of iodine deficiency, and as a reactant in the Finkelstein reaction.-Uses:Sodium iodide is commonly used to treat and prevent iodine deficiency....
detectors at 7% . The improved resolution is due to a photoelectron yield of 160% that achieved with sodium iodide. Another advantage of LaBr3 is the nearly flat photo emission over a 70 °C temperature range (~1% change in light output).
Today LaBr3 detectors are offered with bialkali photomultiplier
Photomultiplier
Photomultiplier tubes , members of the class of vacuum tubes, and more specifically phototubes, are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum...
tubes (PMT) that can be two inches in diameter and 10 or more inches long. However, miniature packaging can be obtained by the use of silicon drift detectors (SDD). These UV enhanced diodes provide excellent wavelength matching to the 380 nm emission of LaBr3. A recent paper presented at the 2005 IEEE Nuclear Science Symposium shows that the SDD has a higher quantum efficiency over the PMT . Moreover the SDD is not as sensitive to temperature and bias drift. The reported spectroscopy performance of the SDD configuration resulted in a 2.8% energy resolution at 662 keV for the detector sizes considered.
LaBr3 introduces an enhanced set of capabilities to a range of gamma spectroscopy
Gamma spectroscopy
Gamma-ray spectroscopy is the quantitative study of the energy spectra of gamma-ray sources, both nuclear laboratory, geochemical, and astrophysical. Gamma rays are the highest-energy form of electromagnetic radiation, being physically exactly like all other forms except for higher photon energy...
radioisotope detection and identification systems used in the homeland security
Homeland security
Homeland security is an umbrella term for security efforts to protect states against terrorist activity. Specifically, is a concerted national effort to prevent terrorist attacks within the U.S., reduce America’s vulnerability to terrorism, and minimize the damage and recover from attacks that do...
market. Isotope identification utilizes several techniques (known as algorithms) which rely on the detector’s ability to discriminate peaks. The improvements in resolution allow more accurate peak discrimination in ranges where isotopes often have many overlapping peaks. This leads to better isotope classification. Screening of all types (pedestrians, cargo, conveyor belts, shipping containers, vehicles, etc.) often requires accurate isotopic identification to differentiate concerning materials from non-concerning materials (medical isotopes in patients, naturally occurring radioactive materials, etc.) Heavy R&D and deployment of instruments utilizing LaBr3 is expected in the upcoming years. (List of companies who manufacture commercial off-the-shelf Radiation Isotope Identifiers for Homeland Security: Canberra Industries, ORTEC, Berkeley Nucleonics spectra sample and spectroscopy example, Polimaster )