Lanthanum(III) bromide (LaBr₃) is an

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

halide salt of

lanthanum Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lantha ...

. 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 Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

and water-soluble. There are several

hydrates In chemistry, a hydrate is a substance that contains water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the ...

, La₃Br·x H₂O, of the salt also known. It is often used as a source of lanthanum in chemical synthesis and as a scintillation material in certain applications.

Lanthanum bromide scintillation detector

The

scintillator A scintillator is a material that 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. re-emit the absorbed ...

material

cerium Cerium is a chemical element with the symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the +3 o ...

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lanthanum bromide Lanthanum(III) 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. ...

(LaBr₃:Ce) was first produced in 2001. LaBr₃:Ce-based radiation 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 (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions (I ...

detectors at 7%. The improved resolution is due to a photoelectron yield that is 160% greater than is achieved with sodium iodide. Another advantage of LaBr₃:Ce 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 A photomultiplier is a device that converts incident photons into an electrical signal. Kinds of photomultiplier include: * Photomultiplier tube, a vacuum tube converting incident photons into an electric signal. Photomultiplier tubes (PMTs for sho ...

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 a

silicon drift detector Silicon drift detectors (SDDs) are X-ray radiation detectors used in x-ray spectrometry ( XRF and EDS) and electron microscopy. Their chief characteristics compared with other X-ray detectors are: *high count rates *comparatively high energy resolu ...

(SDD) or a

Silicon Photomultiplier Silicon photomultipliers, often called "SiPM" in the literature, are solid-state single-photon-sensitive devices based on Single-photon avalanche diode (SPAD) implemented on common silicon substrate. The dimension of each single SPAD can vary fro ...

(SiPM).A. Dawood Butt et al., "Comparison of SiPM and SDD based readouts of 1″ LaBr3:Ce scintillator for nuclear physics applications," 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), San Diego, CA, 2015, pp. 1-4. doi: 10.1109/NSSMIC.2015.7581734 These UV enhanced diodes provide excellent wavelength matching to the 380 nm emission of LaBr₃. The SDD is not as sensitive to temperature and bias drift as PMT. 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-ray spectroscopy is the quantitative study of the energy spectra of gamma-ray sources, such as in the nuclear industry, geochemical investigation, and astrophysics. Most radioactive sources produce gamma rays, which are of various energie ...

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

detection and identification systems used in the

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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 isotope A medical isotope is an isotope used in medicine. The first uses of isotopes in medicine were in radiopharmaceuticals, and this is still the most common use. However more recently, separated stable isotopes have also come into use. Examples of ...

s in patients, naturally occurring radioactive materials, etc.) Heavy R&D and deployment of instruments utilizing LaBr₃ is expected in the upcoming years.

References

{{Inorganic bromides Lanthanum compounds Bromides Phosphors and scintillators Lanthanide halides *