WO2011016880A1 - Nouveaux scintillateurs à base d'halogénure de strontium-baryum et césium dopé aux lanthanides - Google Patents

Nouveaux scintillateurs à base d'halogénure de strontium-baryum et césium dopé aux lanthanides Download PDF

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WO2011016880A1
WO2011016880A1 PCT/US2010/029719 US2010029719W WO2011016880A1 WO 2011016880 A1 WO2011016880 A1 WO 2011016880A1 US 2010029719 W US2010029719 W US 2010029719W WO 2011016880 A1 WO2011016880 A1 WO 2011016880A1
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range
value
inorganic scintillator
inorganic
scintillator
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PCT/US2010/029719
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Ramesh B. Borade
Edith Bourret-Courchesne
Stephen E. Derenzo
Gregory Bizarri
Stephen M. Hanrahan
Zewu Yan
Anurag Chaudhry
Andrew Canning
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The Regents Of The University Of California
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Publication of WO2011016880A1 publication Critical patent/WO2011016880A1/fr
Priority to US13/272,152 priority Critical patent/US9053832B2/en
Priority to US14/731,302 priority patent/US10795032B2/en
Priority to US17/024,590 priority patent/US11360222B2/en

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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7728—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing europium
    • C09K11/7732—Halogenides
    • C09K11/7733—Halogenides with alkali or alkaline earth metals
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/12—Halides
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens
    • G21K2004/06—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens with a phosphor layer

Definitions

  • the present invention is in the field of inorganic crystals with scintillation properties useful as gamma-ray detectors.
  • the present invention provides for a composition comprising an inorganic scintillator comprising a lanthanide-doped strontium-barium cesium halide useful for detecting nuclear material.
  • the present invention provides for an inorganic scintillator having the formula:
  • the inorganic scintillator has the formula:
  • the inorganic scintillator has the formula:
  • the inorganic scintillator has the formula:
  • the inorganic scintillator has the formula:
  • the inorganic scintillator has the formula:
  • M 1n CsI 5 ILn 1 X (IIa); wherein M is Sr or Ba; Ln 1 is a lanthanide with a valence of 2+; x has a value having the range 0 ⁇ x ⁇ 2; m has a value having the range 0 ⁇ m ⁇ 2; and, x+m 2.
  • the inorganic scintillator has the formula:
  • M m CsCl 5 ILn 1 X (lib); wherein M is Sr or Ba; Ln 1 is a lanthanide with a valence of 2+; x has a value having the range 0 ⁇ x ⁇ 2; m has a value having the range 0 ⁇ m ⁇ 2; and, x+m 2.
  • the inorganic scintillator has the formula:
  • the present invention also provides for an inorganic scintillator having the formula:
  • the inorganic scintillator has the formula:
  • the inorganic scintillator has the formula:
  • the inorganic scintillator has the formula:
  • the inorganic scintillator has the formula:
  • the inorganic scintillator has the formula:
  • the inorganic scintillator is a single crystal having at least one dimension of a length of at least 1 mm, at least 5 mm, at least 1 cm, or at least 3 cm, or a length at least sufficient to stop or absorb gamma-radiation.
  • the present invention provides for an inorganic scintillator described and/or having the properties described in Examples 1-4.
  • the present invention also provides for a composition
  • a composition comprising essentially of a mixture of halide salts (compriosing optionally Sr halide, optionally Ba halide, Cs halide, and Ln 1 Or Ln 2 halide) useful for producing the inorganic scintillator, wherein each elements relative to each other within the composition have a stoichiometry essentially equivalent to the stoichiometry of the elements in the compounds of formula (I), (Ia), (Ib), (Ic), (II), (Ha), (lib), (lie), (III), (Ilia), (TJIb), (HIc), (IV), (IVa), (IVb), and (IVc).
  • halide salts comprising optionally Sr halide, optionally Ba halide, Cs halide, and Ln 1 Or Ln 2 halide
  • the halide salts can be powdered crystals.
  • the halide salts are essentially pure. Such halide salts are commercially available.
  • the present invention further provides for a method for producing the composition comprising an inorganic scintillator as described herein comprising: (a) providing a composition comprising essentially of a mixture of halide salts useful for producing the inorganic scintillator as described herein, (b) heating the mixture so that the iodide salts start to react, and (c) cooling the mixture to room temperature such that the composition comprising an inorganic scintillator is formed.
  • the invention provides for a device comprising a composition comprising an inorganic scintillator or lanthanide-doped strontium-barium cesium halide of the present invention and a photodetector.
  • the device is useful for the detection of an ionizing radiation, such as gamma radiation.
  • the device is useful for industrial, medical, protective and defensive purpose or in the oil and nuclear industry.
  • the device is a gamma ray (or like radiation) detector which comprises a single crystal of inorganic scintillator or lanthanide-doped strontium-barium cesium halide of the present invention.
  • the scintillator crystal When assembled in a complete detector, the scintillator crystal is optically coupled, either directly or through a suitable light path, to the photosensitive surface of a photodetector for generation of an electrical signal in response to the emission of a light pulse by the scintillator.
  • the inorganic scintillator of the invention possesses certain important characteristics, most notably high light output, very short decay time and high detection efficiency, that make it superior to prior scintillators as a gamma ray or like radiation detector, in particular for homeland security applications, such as nuclear material detection.
  • Figure 1 shows the emission spectrum of a Ba 2 CsIs:2% Eu crystal under x-ray excitation.
  • Figure 2 shows the pulsed x-ray measurement of Ba 2 CsIs :2% Eu showing a decay time for 85% of the emitted light of less than 1.2 ⁇ s.
  • Figure 3 shows the response of a Ba 2 CsIs :2% Eu crystal to gamma irradiation showing an energy resolution of 3.8% at 662 keV.
  • Figure 4 is a diagrammatic view of one embodiment of a scintillation detector in accordance with the present invention.
  • Figure 5 shows the measured luminescence intensity of Ba 2 CsIs :Eu crystals for different molar percent concentrations of Eu.
  • Figure 6 shows the emission spectrum of a Ba 2 CsIs :7% Eu crystal under x-ray excitation.
  • Figure 7 shows the pulsed x-ray measurement of Ba 2 CsIs :7% Eu showing a decay time for more than 80% of the emitted light of less than 1.2 ⁇ s.
  • Figure 8 shows an image of a Ba 2 CsIs :Eu crystal in the ampoule as-grown (topO and in the ampoule as viewed scintillating under UV illumination (bottom).
  • the white bar shows the scale.
  • Figure 9 shows emission spectrum of a Sr 2 CsIs :2% Eu crystal under x-ray excitation.
  • the emission maximum is at -438 nm, and the luminosity is 56,000 Ph/MeV.
  • Figure 10 shows the pulsed x-ray measurement of Sr 2 CsIs :2% Eu showing a maximum luminosity of 45,000 Ph/MeV.
  • Figure 11 shows the measured luminescence intensity of Sr 2 CsIs :Eu crystals for different molar percent concentrations of Eu
  • halide refers to a chloride, bromide, or iodide.
  • Useful qualities for the inorganic scintillators of the present invention are high light yields, fast luminescence decay (such as, equal to or less 1000 ns), good stopping power, high density, good energy resolution, ease of growth, and stability under ambient conditions.
  • the inorganic scintillator can be in a poly crystalline powder or a single crystal form.
  • the crystal can be any size with an average volume of at least 0.001 mm 3 , at least 1 mm 3 , at least 5 mm 3 , at least 10 mm 3 , at least 100 mm 3 , at least 3 cm 3 , at least 1 cm 3 , or at least 10 cm 3 .
  • the crystal can be any size with at least one dimension of the crystal having a length of at least 100 ⁇ m, at least 1 mm, at least 2 mm, at least 5 mm, at least 1 cm, at least 3 cm, at least 5 cm, or at least 10 cm.
  • the crystal has at least one dimension having a length that is of sufficient length, or depth, to stop or absorb gamma- radiation in order to electronically detect the gamma-radiation.
  • the lanthanide atoms in the inorganic scintillator substitute for the strontium atoms and/or barium atoms and optionally the cesium atoms.
  • the inorganic scintillators of the present invention are useful as they are scintillators and they produce a useful bright and fast scintillation in response to irradiation by short- wavelength high energy light, such as x-ray or gamma rays.
  • the crystals of the inorganic scintillator also have the added advantage of having the property of readily growing into crystals. Large size crystals can be grown by the following technique: Bridgman growth and related techniques, Czochralski growth and related techniques, the traveling heater method and related techniques.
  • Ln 1 is a lanthanide with a valence of 2+
  • x has a value having the range 0.001 ⁇ x ⁇ 2.
  • Ln 1 is a lanthanide with a valence of 2+
  • x has a value having the range O.OOl ⁇ x ⁇ l.
  • Ln 1 is a lanthanide with a valence of 2+
  • x has a value having the range 0.001 ⁇ x ⁇ 0.5.
  • Ln 1 is a lanthanide with a valence of 2+
  • x has a value having the range 0.01 ⁇ x ⁇ 0.5.
  • Ln 1 is a lanthanide with a valence of 2+
  • x has a value having the range 0.02 ⁇ x ⁇ 0.2.
  • suitable amounts of Ln 1 range from over 0% to 10%, over 0% to 7%, over 0% to 5%, 1% to 10%, 1% to 5%, 1% to 4%, or 2% to 3%.
  • Ln 2 is a valence of 3+
  • a has a value having the range 0.001 ⁇ a ⁇ l.
  • Ln 2 is a lanthanide with a valence of 3+
  • a has a value having the range 0.001 ⁇ a ⁇ 0.5.
  • Ln 2 is a lanthanide with a valence of 3+
  • a has a value having the range 0.01 ⁇ a ⁇ 0.5.
  • Ln 2 is a lanthanide with a valence of 3+
  • a has a value having the range 0.02 ⁇ a ⁇ 0.2.
  • the inorganic scintillator is a single crystal having at least one dimension of a length of at least 1 mm, at least 5 mm, at least 1 cm, or at least 3 cm, or a length at least sufficient to stop or absorb gamma-radiation.
  • the present invention provides for an inorganic scintillator described and/or having the properties described in Example 1-4. Characterization of the Inorganic Scintillators
  • the crystals of the invention can be characterized using a variety of methods.
  • the crystals can be characterized regarding X-ray diffractometry, X-ray luminescence spectra, X- ray fluorescence for concentration of activators, and/or pulsed X-ray time response.
  • X-ray diffractometry determines the composition of crystalline solids, such as crystalline phase identification.
  • X-ray luminescence spectra determines the spectra components.
  • Pulsed X-ray time response determines luminosity, decay times, and fractions.
  • X-ray luminescence is used to determine the relative luminosity of a crystal.
  • An X-ray excited emission spectra is obtained of a crystal by irradiating the crystal with an X-ray and collecting the emission light by a CCD detector.
  • the luminosity of the inorganic scintillator is more than the luminosity of yttrium aluminium perovskite (YAP) and/or bismuth germanate (BGO). In further embodiments of the invention, the luminosity of the inorganic scintillators is more than double the luminosity of YAP and/or BGO.
  • YAP yttrium aluminium perovskite
  • BGO bismuth germanate
  • the single crystal inorganic scintillators such as Ba 2 Csl 5 :2% Eu, have a luminescence output equal to or more than 60,000 photons/MeV, and a decay of equal to or more than 85% of the emitted light in a period equal to or less than 1.2 ⁇ s.
  • the single crystal inorganic scintillators such as Ba2Csl5:7% Eu, has a decay of equal to or more than 80% of the emitted light in a period equal to or less than 1.2 ⁇ s.
  • the single crystal inorganic scintillators such as Sr 2 CsI 5 :2% Eu, has a decay of equal to or more than 70% of the emitted light in a period equal to or less than 1.2 ⁇ s.
  • the single crystal inorganic scintillators such as Sr 2 CsI 5 : 1-10% Eu, has a X-ray excited luminescence equal to or more than the luminosity shown in Figure 11.
  • the inorganic scintillators of the invention can be prepared using a variety of methods.
  • the crystals useful for fabrication of luminescent screens can be prepared by a solid-state reaction aided, or optionally not aided, by a flux of iodides as described herein.
  • the single crystals are prepared by providing a composition comprising essentially of a mixture of halide salts useful for producing the inorganic scintillator as described herein.
  • the mixture is heated to a temperature of up to about 900°C using a simple programmable furnace to produce a reactive molten mixture.
  • the reaction is maintained at temperature for the mixture to fully react and produce the desired melt.
  • the resultant molten product of reaction is then cooled slowly at about 2 to 5°C/minute.
  • a particular method of preparing the inorganic scintillator of the invention is as follows: Bridgman growth and related techniques, Czochralski growth and related techniques, the traveling heater method and related techniques. These methods can be used to produce the inorganic scintillator as single crystals on a one-by-one basis.
  • the Bridgman growth technique is a directional solidification process.
  • the technique involves using an ampoule containing a melt which moves through an axial temperature gradient in a furnace. Single crystals can be grown using either seeded or unseeded ampoules.
  • the Bridgman growth technique is taught in Robertson J. M., 1986, Crystal growth of ceramics: Bridgman-Stockbarger method in Bever: 1986 "Encyclopedia of
  • the Czochralski growth technique comprises a process of obtaining single-crystals in which a single crystal material is pulled out of the melt in which a single-crystal seed is immersed and then slowly withdrawn; desired optical properties and doping level is accomplished by adding dopants to the melt.
  • the Czochralski growth technique is taught in J. Czochralski, "Ein 14maschinezzy Anlagen Anlagenstallisationsgeschwindigheit der Metalle” [A new method for the measurement of the crystallization rate of metals], Z. Phys. Chemie 92 (1918) 219-221, which is incorporated by reference. The method is well-know to those skilled in the art in producing a wide variety of componds, including semiconductors and scintillator materials (such as LaBr 3 : Ce).
  • a particular method of preparing inorganic scintillators of the invention is the ceramic method which comprises the following steps: The reactant mixture is placed in a container, such as a glove box, filled with one or more inert gas, such as nitrogen gas. The container is under a very dry condition. The dry condition is required due to the hygroscopic nature of the halides within the reactant mixture.
  • the two or more powder reactants are ground together, such as with a mortar and pestle, for a sufficient period, such as about 10 minutes, to produce a reactant mixture.
  • a suitable organic solvent or solution can be further added, and grinding can take place until the mixture appears dry.
  • the reactant mixture is sintered under high temperature and pressure.
  • the single crystals of the inorganic scintillator can be grown by melting and re-solidifying the pre-synthesized compounds in powder form, such as described herein, or directly from melting the mixtures of the halides salts and lanthanide halides used as activators. To grow best performing crystals the starting compounds might need to be purified further by zone refining.
  • Growing the single crystal involves loading the mixtures, such as described herein, in a quartz ampoule in a dry environment and sealing the ampoule using a high temperature torch, maintaining the dry environment at a reduced pressure, in the ampoule.
  • the ampoule is then placed in a furnace.
  • the growth of the crystal can be performed by a variation of the known vertical "Bridgman" technique.
  • the compound is melted, let to homogenized at a temperature above the melting point and the compound is solidified in a directional manner in a temperature gradient.
  • the ampoule is shaped to provide a nucleation site at the bottom (conical shape). The solidification front moves upward. Horizontal configurations and other growth techniques such as Czochralski (may need to pressurized the growth chamber) could be used.
  • the method for producing the composition comprising the inorganic scintillator of the present invention comprises: (a) providing a sealed container containing the composition comprising essentially of a mixture of halide salts useful for producing the inorganic scintilaltor of the present invention, (b) heating the container sufficiently to produce a melted mixture, and (c) solidying or growing a crystal from the melted mixture, such that the composition comprising the inorganic scintillator of the present invention is produced.
  • the method for producing the composition comprising the inorganic scintillator of the present invention comprises: (a) providing the composition comprising essentially of a mixture of halide salts, (b) loading the halide salts in a suitable container, (c) sealing the container, (d) heating the container sufficiently to produce a melted mixture, and (e) solidying or growing a crystal from the melted mixture, such that the composition comprising the inorganic scintillator of the present invention is produced.
  • the container is a quartz container.
  • the sealed container is an ampoule.
  • the heating takes place in a furnace.
  • the mixture is heated to a suitable temperature to melt the halides in the mixture.
  • a temperature or a range of temperatures suitable for melting the mixture of halides For example, for producing Ba 2 CsIsIEu, a temperature of about 650- 750 0 C is suitable.
  • the furnace can be a Bridgman-type or float-zone-type (mirror-furncae where heat s supplied by halogen lamps, or induction heated furnace). When using a Bridgman configuration, the crystal is solidified from the melt directionally.
  • the crystal When using the float-zone configuration, the crystal is solidified from a narrow molten zone of a pre -reacted charge. In both cases the growth rate of the crystal can be within a thermal gradient across the soli/liquid interface. The ratio of gradient to growth rate determines the stability of the interface. The growth rate can be decreased if the thermal gradient is increased. Typical thermal gradient can be more than l°C/cm. Once all solidified, the crystal is colled slowly. The cooling rate can be in the range from less than l°C/hr to more than 20°C/hr.
  • the resulting crystals are then characterized by the methods described herein.
  • the resulting crystals also have properties similar to those described herein.
  • the present invention provides for a gamma ray or x-ray detector, comprising: a scintillator composed of a transparent single crystal of the inorganic scintillator of the present invention, and a photodetector optically coupled to the scintillator for producing an electrical signal in response to the emission of a light pulse by the scintillator.
  • the inorganic scintillators of this invention have many advantages over other known crystals.
  • the inorganic scintillators produce a luminescence in response irradiation, such as irradiation by alpha-, beta-, or gamma-radiation, that is brighter and faster than known and commercially used scintillators.
  • the scintillating crystals have a number of applications as detectors, such as in the detection of gamma-ray, which has use in national security, such as for detection of nuclear materials, and medical imaging applications.
  • the invention is useful for the detection of ionizing radiation.
  • Applications include medical imaging, nuclear physics, nondestructive evaluation, treaty verification and safeguards, environmental monitoring, and geological exploration. This will be a major improvement, providing much finer resolution, higher maximum event rates, and clearer images.
  • activated inorganic scintillator crystals of the present invention can be useful in positron emission tomography (PET).
  • the invention also relates to the use of the scintillating material above as a component of a detector for detecting radiation in particular by gamma rays and/or X-rays.
  • a detector especially comprises a photodetector optically coupled to the scintillator in order to produce an electrical signal in response to the emission of a light pulse produced by the scintillator.
  • the photodetector of the detector may in particular be a photomultiplier, photodiode, or CCD sensor.
  • a particular use of this type of detector relates to the measurement of gamma or x-ray radiation, such a system is also capable of detecting alpha and beta radiation and electrons.
  • the invention also relates to the use of the above detector in nuclear medicine apparatuses, especially gamma cameras of the Anger type and positron emission tomography scanners (see, for example C. W. E. Van Eijk, "Inorganic Scintillator for Medical Imaging",
  • the invention relates to the use of the above detector in detection apparatuses for oil drilling, (see, for example "Applications of scintillation counting and analysis", in “Photomultiplier tube, principle and application”, chapter 7, Philips; hereby incorporated by reference).
  • Figure 4 shows a gamma ray detector.
  • the detector can be one as described in U.S. Patent No. 4,958,080, hereby incorporated by reference. It will be understood, of course, that the utility of the novel single crystal inorganic scintillator of the invention is not limited to the detection of gamma radiation but that it has general application to the detection of other types of like radiation, e.g. X-rays, cosmic rays, and energetic particles.
  • a single crystal inorganic scintillator 10 is shown encased within the housing 12 of a gamma ray detector.
  • One face 14 of the scintillator is placed in optical contact with the photosensitive surface of a photomultiplier tube 16.
  • the light pulses could be coupled to the photomultiplier via light guides or fibers, lenses, mirrors, or the like.
  • the photomultiplier can be replaced by any suitable photodetector such as a photodiode, microchannel plate, etc.
  • the other faces 18 of the inorganic scintillator are preferably surrounded or covered with a reflective material, e.g.
  • Teflon tape magnesium oxide powder, aluminum foil, or titanium dioxide paint.
  • Light pulses emitted by the crystal inorganic scintillator upon the incidence of radiation are intercepted, either directly or upon reflection from the surfaces 18, by the photomultiplier, which generates electrical pulses or signals in response to the light pulses. These electrical output pulses are typically first amplified and then subsequently processed as desired, e.g. in a pulse height amplifier, to obtain the parameters of interest regarding the detected radiation.
  • the photomultiplier is also connected to a high voltage power supply, as indicated in Figure 4.
  • All of the components and materials referred to in connection with Figure 4 are conventional, and thus need not be described in detail.
  • Powders of the composition Ba 2 CsIs :2% Eu are obtained by a solid state route using commercial chemicals without further purification. The compound was subsequently grown as a single crystal using the Bridgman technique.
  • Figure 1 shows the emission spectrum of a Ba 2 Csl 5 :2% Eu crystal under x-ray excitation. The emission maximum is at ⁇ 430 nm. The compound is particularly bright with a luminosity of more than 60,000 ph/MeV and a very good energy resolution of less than 4%.
  • Figure 2 shows the pulsed x-ray measurement showing a decay time for 85% of the emitted light of less than 1.2 ⁇ s.
  • Figure 3 shows the response of a Ba 2 CsIs :2% Eu crystal to gamma irradiation showing an energy resolution of 3.8% at 662 keV.
  • Powders of the composition Ba 2 CsIs :7% Eu are obtained by a solid state route using commercial chemicals without further purification. The compound was subsequently grown as a single crystal using the Bridgman technique.
  • Figure 6 shows the emission spectrum of a Ba 2 CsI 5 :7% Eu crystal under x-ray excitation. The emission maximum is at ⁇ 430 nm.
  • Figure 7 shows the pulsed x-ray measurement showing a decay time for more than 80% of the emitted light of less than 1.2 ⁇ s.
  • Ba 2 CsI 5 :Eu crystals are measured and compared. The results are shown in Figure 5. The luminescence intensities of all of the crystals tested are comparable to each other. Of the crystals tested, the crystal with 7% Eu shows the highest luminescence intensity.
  • Crystals of Sr 2 CsI 5 :Eu with Eu concentrations of 1%, 2%, 3%, 5%, 7%, and 10% are produced using the methods described herein. Powdered samples are prepared by solid state reactions at high temperature. The starting materials are SrI 2 , CsI and EuI 2 (all commercially available from Aldrich). Stoichemetric amounts of the starting reagents are thoroughly mixed and ground together using mortar pestle in a dry box. The mixture is placed in a quartz tube that is evauated to 10- torr at 60 0 C to 150 0 C for 1 hour to 2 hour and thewn sealed and placed in a tuibe furnace for reaction.
  • the sealed quartz tuibe is heated at 600 0 C to 725 0 C for 2 hour to 24 hour.
  • the solid product is recovered by opening the quartz tube inside a dry box.
  • Al powder samples are characterized by X-ray diffraction technique for phase identification and x-ray excited luminescence for emission and pulsed x-ray for decay measurements. Table 1 shows the synthesis examples with synthesis conditions.
  • Powders of the composition Eu-doped strontium cesium halide are obtained by a solid state route using commercial chemicals without further purification and evaluated for scintillation properties.
  • the prese3nt results indicate that the compositons are useful as scintillators.
  • Figures 9 and 10 show the X-ray lumininescence and decay curve for one of the representative sample. The emission maximum is at -438 nm and the estimated luminosity in the powder form is 56,000 Ph/MeV. Luminescence decay measurements indicate that the scintillator's response is fast with decay time 322.2 ns at 24%, and 1,180 ns at 70%.
  • Figure 11 shows luminosity as a function of Eu incorporation in the Sr 2 CsIs structure. The optimum Eu concentration appears to be about 1-4% or about 2-3%. Crystals of these concentrations are bright scintillators.

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Abstract

La présente invention porte sur une composition comprenant un scintillateur inorganique comprenant un halogénure et de strontium-baryum et césium dopé aux lanthanides utile pour la détection d'une matière nucléaire.
PCT/US2010/029719 2009-05-07 2010-04-01 Nouveaux scintillateurs à base d'halogénure de strontium-baryum et césium dopé aux lanthanides WO2011016880A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US13/272,152 US9053832B2 (en) 2009-05-07 2011-10-12 Lanthanide doped strontium-barium cesium halide scintillators
US14/731,302 US10795032B2 (en) 2009-05-07 2015-06-04 Lanthanide doped barium mixed halide scintillators
US17/024,590 US11360222B2 (en) 2009-05-07 2020-09-17 Lanthanide doped cesium barium halide scintillators

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CN105293942A (zh) * 2015-11-16 2016-02-03 宁波大学 含稀土离子掺杂碘化钙微晶的玻璃薄膜及其制备方法
CN106801254A (zh) * 2017-01-22 2017-06-06 山东大学 一种CsSrI3闪烁晶体的制备方法
CN106801254B (zh) * 2017-01-22 2019-10-01 山东大学 一种CsSrI3闪烁晶体的制备方法

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