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WO2024118778A1 - Matériau scintillateur et procédé de fabrication - Google Patents

Matériau scintillateur et procédé de fabrication Download PDF

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Publication number
WO2024118778A1
WO2024118778A1 PCT/US2023/081607 US2023081607W WO2024118778A1 WO 2024118778 A1 WO2024118778 A1 WO 2024118778A1 US 2023081607 W US2023081607 W US 2023081607W WO 2024118778 A1 WO2024118778 A1 WO 2024118778A1
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equal
material according
lix
less
flux
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Vladimir Ouspenski
Mikayel ARZAKANTSYAN
Peter R. Menge
Rémi DANET
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Luxium Solutions LLC
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Luxium Solutions LLC
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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
    • C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
    • C09K11/7767—Chalcogenides
    • C09K11/7768—Chalcogenides with alkaline earth metals
    • 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
    • C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
    • C09K11/7772—Halogenides
    • 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
    • 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
    • C30B9/00—Single-crystal growth from melt solutions using molten solvents
    • C30B9/04—Single-crystal growth from melt solutions using molten solvents by cooling of the solution
    • C30B9/08—Single-crystal growth from melt solutions using molten solvents by cooling of the solution using other solvents
    • C30B9/12—Salt solvents, e.g. flux growth
    • 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 concerns an inorganic scintillator material, a process for manufacturing it and the use of this material in detectors for a dual detection of gamma rays and thermal neutrons.
  • Inorganic scintillator materials are widely used in detectors for gamma rays, X-rays, cosmic rays, and particles with an energy greater than 1 KeV. Such detectors are used in industry for thickness or weight measurements, in nuclear medicine, physics, chemistry, security systems, in particular for the control of illicit objects, or in the search for oil deposits and other geophysical applications.
  • Inorganic scintillator materials consist of a crystal that responds to incident radiation by emitting a light pulse. This crystal is transparent in the wavelength range of the light pulse,
  • a detector incorporating such a crystal can be manufactured.
  • the crystal In response to incident radiation, the crystal emits light, preferably in the UV or visible spectrum.
  • An optical detection means receives this light and produces an electrical signal proportional to the number of photons received.
  • This signal is typically represented in the form of an energy spectrum histogram. Analysis of the spectrum makes it possible to discriminate the various peaks and deduce information about the composition of the incident radiation. The better the energy resolution (“PHR" - Pulse Height Resolution) (low PHR value), the better the peaks can be discriminated from one another.
  • PHR Pulse Height Resolution
  • LaCI ,:Ce (Brightness 350 TM) and LaBr ⁇ Ce (Brightness-380 TM) are reported in particular in US7479637 and US7067816. These materials are also described in S. Kraft et al. “Development and Characterization of Large La-Halide Gamma-Ray Scintillators for Future Planetary Missions". IEEE TRANSACTIONS ON NUCLEAR SCIENCE, V. 54, N° 4, August 2007, in W. Drozdowski et al.
  • the inorganic scintillator material LaBr3:Ce:Sr is also known, in particular from US 10053624 and M.S. Alekhin et al. "Improvement ofc-ray energy resolution of LaBr 3 :Ce 3+ scintillation detectors by Sr 2+ and Ca 2+ co-doping" , APPLIED PHYSICS LETTERS 2013, V.102, No. 161915.
  • this material does not allow a dual detection of gamma rays and thermal neutrons, due to the absence in the crystalline matrix of an isotope with a high thermal neutron absorption capacity.
  • Transparent ceramic materials based on GYGAG:Ce oxide i.e. (Gd, Y)j (Al, Ga)s O12 (Ce) also show a PHR energy resolution in excess of 4.5% (N. J. Cherepy et al. "Comparative gamma spectroscopy with Srh (Eu), GYGAG(Ce) and Bi-loaded plastic scintillator” . IEEE Nuclear Science Symposium & Medical Imaging Conference, 2010, pp. 1288-1291).
  • CLLBs i.e., CsjLiLaBre (Ce) and CS2 6 LiLa(Br,Cl)e (Ce), also known by the acronym CLLBC, described in G.Hull et al. "Detection properties and internal activity of newly developed La-containing scintillator crystals", Nucl. Instr. & Meth Phys. Res. Sect. A. V. 925, 1 May 2019, pp. 70-75. The PHR energy resolution of these materials is always better than 3.3%.
  • the CLYC material i.e., Cs2LiYCle (Ce), described in N. Dinar et al.
  • a purpose of the invention is to meet this need, at least in part.
  • FIG. 1 includes an illustration of a recording of an energy spectrum with 137 Cs, in accordance with one embodiment.
  • FIG. 2 includes an illustration of a recording of an energy spectrum with 252 Cf, in accordance with one embodiment.
  • FIG. 3 includes an illustration of a median longitudinal section of a quartz ampoule which can be used to manufacture a composite crystal, in accordance with one embodiment.
  • FIG. 4 includes an illustration of a growth method and synthesis of a crystal in a Bridgman furnace, in accordance with one embodiment.
  • FIG. 5 includes an illustration of a FoM ( Figure of Merit) measurement for the parameter of gamma ray and thermal neutron discrimination, in accordance with one embodiment.
  • FoM Figure of Merit
  • FIG. 6 includes an illustration of after gamma-ray irradiation of the afterglow (normalized signal) of a crystal described herein, in accordance with one embodiment.
  • the invention proposes an inorganic scintillator material in the form of a composite single crystal Lai-z-vCezCv(Bri- Ax)3-v+y+wLiyNa w -(LiX)a-(NaY)b consisting of a single-crystal matrix Lai-z-vCezCv(Bri-xAx)3-v+y+wLiyNa w and LiX inclusions, and optionally NaY inclusions, embedded in said single-crystal matrix, wherein
  • - A is selected among the elements I and Cl ;
  • - C is selected among the elements Ca, Sr, Ba and Mg, preferably among Sr and Ca;
  • - X is selected among the elements F, Cl, Br, I and combinations thereof;
  • - Y is selected among the elements F, Cl, Br, I and combinations thereof;
  • - a, b, x, v, y, w and z are molar indices for LiX, NaY, A, C, Li, Na and Ce, respectively.
  • this material comprising a lattice of Lai-z-vCezC v (Bri-xAx)3-v+y+wLiyNa w and LiX inclusions, has a PHR energy resolution, at the isotopic source 137 Cs, of less than 3.0%, as well as a good gamma-ray and thermal neutron detection capability.
  • a material according to the invention may further have one or more of the following optional features:
  • the material in single crystal form preferably has a formula selected among:
  • C being selected among Ca, Sr, Ba and Mg, preferably being Sr,
  • C being selected among Ca, Sr, Ba and Mg, preferably being Ca, wherein
  • - A is selected among I and Cl;
  • - X is selected among I, Br, Cl, F and combinations thereof;
  • the single-crystal matrix is selected among LaBr 3 :Ce, LaBr3:Ce:Sr, CeBn and CeBr3:Ca;
  • the material is LaBr3:Ce-(LiBr) a ;
  • - x is less than or equal to 0.10, preferably less than or equal to 0.04, preferably less than or equal to 0.03, preferably zero;
  • - v is preferably greater than 0.001, and/or less than or equal to 0.05, preferably less than or equal to 0.004, preferably less than or equal to 0.003, preferably equal to 0.003;
  • - a is greater than 0.01, preferably greater than or equal to 0.05, and/or less than or equal to 0.2, preferably less than or equal to 0.18;
  • - z can be greater than 0.005.
  • z is less than or equal to 0.30, preferably less than or equal to 0.10, preferably less than or equal to 0.05. In another preferred embodiment, z is greater than 0.9, greater than 0.95, preferably equal to 1.
  • x is greater than 0.02 or even greater than 0.04.
  • the invention also relates to a process for manufacturing a scintillator material according to the invention, comprising the following successive steps: a) preparing a starting charge having a composition suitable for the composition of said material; b) synthesizing the composite single crystal, from the starting charge, by a vertical thermal gradient crystallization method or by Edge Defined Film Fed Growth method, preferably by a vertical thermal gradient crystallization method, preferably by the Bridgman method.
  • the starting charge comprises a flux providing Li, or "first flux", preferably a LiX flux, X being selected among F, Cl, Br and I, preferably a LiBr flux.
  • first flux preferably a LiX flux, X being selected among F, Cl, Br and I, preferably a LiBr flux.
  • the addition of a flux is a known technique for crystal synthesis, in particular for modifying the melting temperature of the starting charge.
  • the inventors have discovered that adding a LiX flux to a so-called single-crystal matrix provides both a double detection and a good PHR energy resolution. This result was unexpected, as Lithium Li is known to have a strong propensity to segregate and thus deteriorate the optical properties of the crystalline matrix.
  • the inventors found that, in matrices with a hexagonal structure, e.g., containing lanthanum La, inclusions originating from the flux could advantageously precipitate between the hexagonal units. Without being bound by this theory, this is how they explain that optical properties are preserved, despite lithium segregation.
  • the amount of said first flux is greater than 1%, preferably greater than 3%, preferably greater than 4%, and/or less than 10%, preferably less than 8%, more preferably less than 6%, by weight percentage based on the starting charge.
  • the starting charge comprises a second flux, the second flux supplying iodine I.
  • Iodine supply by a second flux advantageously optimizes detection of the light emitted by the scintillator material by a photomultiplier tube.
  • the second flux is preferably Nal, which avoids the use of a flux containing a rare earth, which is highly hygroscopic.
  • the amount of said second flux is greater than 1%, preferably greater than 3%, preferably greater than 4%, and/or less than 10%, preferably less than 8%, preferably less than 6%, by weight percentage based on the starting charge.
  • the second flux may be different from or identical to the first flux, particularly when it is Lil.
  • Lil advantageously avoids the need to use a salt such as Lals or Ceh, which are very hygroscopic.
  • the total amount of the first and second fluxes is greater than 1%, preferably greater than 3%, preferably greater than 4%, and/or less than 10%, preferably less than 8%, preferably less than 6%, by weight percentage based on the starting charge.
  • flux in the rest of the description, it refers to the first flux.
  • the invention also concerns the use of a material according to the invention to detect gamma rays and thermal neutrons, preferably to measure the intensity of gamma rays and thermal neutrons.
  • the material according to the invention can be used in particular as a component of a scintillation detector, especially for applications in industry, in the medical field and/or for the detection of oil for oil drilling, for security systems, especially for the control of illicit objects, e.g. luggage in an airport or goods in containers, e.g. shipping containers.
  • a scintillation detector especially for applications in industry, in the medical field and/or for the detection of oil for oil drilling, for security systems, especially for the control of illicit objects, e.g. luggage in an airport or goods in containers, e.g. shipping containers.
  • it can be used as part of a Positron Emission Tomography scanner or an Anger-type Gamma Camera.
  • the invention also relates to a detector of gamma rays and thermal neutrons comprising:
  • a photodetector optically coupled to the scintillator to produce an electrical signal in response to the reception of a pulse of light emitted by the scintillator.
  • the photodetector of the detector can be a photomultiplier, a photodiode or a SiPM sensor.
  • the invention relates in particular to a security detector, in particular for the identification of objects comprising a material emitting both gamma radiation and thermal neutrons, in particular illicit objects, comprising a material according to the invention.
  • An inorganic scintillator material according to the invention sometimes referred to as a "composite single crystal” in the description, consists of a "host” single crystal matrix, preferably of hexagonal structure, and inclusions incorporated in said matrix and preferably aligned parallel to the growth axis of the matrix. Unless otherwise indicated, “matrix” refers to this host single-crystal matrix.
  • the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” or any other variation thereof, are intended to cover a non-exclusive inclusion.
  • a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus.
  • “or” refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
  • PHR Pulse Height Resolution
  • Figure 1 shows an example of a recording of the energy spectrum obtained from an isotope source 137 Cs with energy at 667 keV, detected with a LaBr3:Ce scintillator material. This recording provides the number of counts as a function of the channel.
  • the PHR energy resolution is equal to d/l*100%. More specifically, to obtain Figure 1 , the scintillation intensity was recorded at room temperature in a glove box (atmospheric humidity in the glove box less than 0.3 ppm) using a 137 Cs gamma source at 662 keV.
  • the photodetector used was an Advanced Photonix APD avalanche photodiode (type 630-70-72-510), operating at a voltage of 1600 V and cooled to 270 K.
  • the crystal sample was wrapped in 3 layers of a Teflon film [using the technique described in J. T. M. de Haas and P. Dorenbos, IEEE Trans. Nucl. Sci. 55, 1086 (2008)], except for the polished side intended for coupling with the photodiode.
  • the output signal from the photodetector was amplified under "shaping time" conditions of 6 s by an ORTEC 672 spectroscopic amplifier. Exposed to the gamma source, the scintillator material produces photons that are detected and counted by the photodetector.
  • the photodetector used is sensitive from UV to IR and can count each photon.
  • the result is an energy spectrum, or "scintillation histogram", with values on the x-axis proportional to the quantity of emitted light detected by the photodetector, and on the y-axis the number of gamma photon interaction events with the scintillator.
  • sintillation histogram an energy spectrum, or "scintillation histogram”
  • the energy resolution is always determined, as described above, for the main peak corresponding to a reference radioactive source 137 Cs at 662 keV, the energy of the main gamma emission. In this way, measurements are comparable.
  • the position of a peak can vary according to the size of the detector, its quality and optical properties, which determine the optical coupling with the photodetector (typically a photomultiplier tube ("PMT”, or “Photo-Multiplier Tube”) or a silicon photomultiplier ("SiPM", or “Silicon Photo-Multiplier”).
  • PMT photomultiplier tube
  • SiPM silicon photomultiplier
  • the composition of the material according to the invention is classically given without taking into account the impurities usual in the technical field of the invention.
  • the usual impurities are generally impurities originating from raw materials, the mass content of which is typically less than 0.1 %, or even less than 0.01 %, and/or parasitic phases, the volume percentage of which is notably less than 1%.
  • a "flux" is a constituent of the starting charge that segregates, i.e., forms inclusions, without integrating into the single-crystal matrix (the crystal's host phase), i.e., without forming part of the single-crystal matrix.
  • LiX inclusions are "embedded” in the matrix insofar as they are arranged within the matrix. However, they form a separate phase from the matrix and are not “integrated” into the matrix.
  • a scintillator material according to the invention can be manufactured according to steps a) to b) described above.
  • step a) a starting charge is prepared having a composition adapted to the composition of said material.
  • the starting charge preferably each raw material source, is preferably in a powder form.
  • the particles are typically between 50 pm and 2 mm in size. However, the particle size distribution has no effect on the material produced, as the powders are melted.
  • the raw materials used include:
  • - LiX powder for example, with a particle size of between 50 pm and 2 mm.
  • the starting charge comprises a source of Li enriched in 6 Li, i.e. which has more 6 Li than natural Li, the atomic ratio in 6 Li/( 6 Li+ 7 Li) preferably being greater than 8%, preferably greater than 10%, preferably greater than 30%, preferably greater than 40%, preferably greater than 50%, preferably greater than 60%, preferably greater than 70%, preferably greater than 80%, preferably greater than 90%, preferably greater than or equal to 95% or preferably greater than or equal to 98%.
  • the starting charge 6 Li is found mainly in inclusions (LiX) and in small quantities in interstitial sites in the single-crystal matrix (Li y ).
  • step b) the composite single crystal is synthesized from the starting charge, preferably by a vertical thermal gradient crystallization method, in a sealed ampoule.
  • the inventors have sought to grow LaBr3:Ce crystals by adding a flux of LiBr using the Czochralski method, well known to those skilled in the art.
  • this method does not allow Li ions to be introduced into the structure of the crystal matrix, except in very small quantities in the interstitial positions of the crystal. They explain this result by the very high segregation of Li in the molten bath.
  • the small amount of Li in the crystalline matrix is not sufficient for the significant absorption of thermal neutrons required for the dual detection of thermal neutrons and gamma rays.
  • the inventors have come up with the idea of adapting the Bridgman vertical synthesis process described by H.Chen et al. (described in "Bridgman Growth ofLaCl3:Ce j+ crystal in non-vacuum atmosphere” , Journal of Alloys and Compounds 449 (2008) 172-175) by introducing a flux supplying Lithium (Li) into the starting charge.
  • crystal growth is initiated by a seed oriented along the hexagonal crystallographic axis "c" ⁇ 0001> and continues along this highly anisotropic crystallographic axis.
  • the cylindrical seed 10 is positioned in a special pocket provided for this purpose at the bottom of a bulb 12.
  • the ampoule is a sealed quartz ampoule, in which the pressure is less than 10" 2 mbar, i.e., "under vacuum”.
  • a mixture of (La,Ce)Br3 powders and LiBr flux is placed in the ampoule.
  • the matrix preferably has a hexagonal structure like that presented by LaBr?, LaCL and CeB (UC14 type) crystals with space group P6_3m, No. 176. Doping does not change the organization of the crystallographic structures of these compounds.
  • the inclusions take the form of fibers, which advantageously do not interfere significantly with optical properties. They can also take the form of "grains" which are inserted and aligned along lines parallel to the crystallographic axis "c" , in the space between the hexagonal structures.
  • a hexagonal structure differs in particular from the orthorhombic structure Cmcm, N°63, of Lab which, with a Ce doping, does not exhibit good scintillation properties.
  • a material according to the invention can be made by any edge defined growth method, and in particular by the Edge Defined Film Fed Growth (or “EFG”) described in particular by V.A.Tatarchenko in "Stability of Crystallization in Edge-Defined Film-Fed Growth from the Mell” in Givargizov, E.I. (eds) Growth of Crystals. Springer, Boston, MA (1986), or preferably by a Bridgman growth method, especially in vacuum-sealed quartz ampoules, provided that said flux is added to the starting charge.
  • the single-crystal matrix has an anisotropic structure, preferably hexagonal, preferably LaBrv
  • the growth preferably results from the addition of a LiBr lithium bromide flux.
  • the growth preferably results from the addition of a Lil flux.
  • the growth preferably results from the addition of a LiCl flux.
  • the LiX inclusions particularly the LiBr inclusions, solidify in a regular structure, mostly in the form of
  • the resulting composite single crystal retains good optical transmission properties along the crystallographic "c" axis, making it suitable as a scintillator material.
  • the inclusions present the form of "fibers" oriented substantially parallel to one another, which could explain the high optical transparency of the composite single crystal according to the invention.
  • the synthesis method described above, using an adapted Bridgman vertical composite crystal synthesis method can be generalized to any vertical gradient crystallization method, and in particular to the methods known by the acronym TGT (for "Temperature Gradient Technique"), described in particular by ZHOU Yongzong in “Growth of High Quality Large Nd:YAG Crystals by Temperature Gradient Technique (TGT)", in Journal of Crystal Growth 78 (1986) 31-35, provided that a flux supplying Li is added to the starting charge.
  • TGT Tempoture Gradient Technique
  • the "EFG”, "Edge Defined Film Fed Growth” method is also effective for synthesizing a scintillator material according to the invention in various forms, provided that a flux supplying Li is added to the starting charge.
  • X Br or I.
  • x ⁇ 0.40 preferably x ⁇ 0.30, preferably x ⁇ 0.20, preferably x ⁇ 0.15, preferably x ⁇ 0.10, preferably x ⁇ 0.05, preferably x ⁇ 0.02, preferably x ⁇ 0.01, preferably x is zero.
  • z > 0.02.
  • z is greater than 0.9, preferably equal to 1.
  • x 0.01 and v > 0.003 and z > 0.04.
  • the dimensions of the composite single crystal constituting the material according to the invention are chosen to effectively stop and detect the radiation to be detected.
  • the single crystal preferably has a volume greater than 10 mm 3 , or even greater than 1 cm 3 , or even greater than 10 cm 3 , or even greater than 100 cm 3 .
  • a detector according to the invention comprising a material according to the invention, can be used in particular:
  • the invention also concerns such a device, and more generally, a device comprising a material according to the invention.
  • the concepts as described in this specification are not limited to the particular application previously described.
  • the radiation detector can be configured for another type of radiation. Many different aspects and embodiments are possible. Some of those aspects and embodiments are described herein. Embodiments may be in accordance with any one or more of the embodiments as listed below.
  • Embodiment 1 An inorganic scintillator material in the form of a composite single crystal of the formula Lai-z.-vCe z Cv(Bri-xAx)3-v+y+wLiyNa w -(LiX) a -(NaY)b consisting of a single-crystal matrix Lai- z -vCe z Cv(Bri-xAx)3-v+y+wLiyNa w and of LiX inclusions, and optionally NaY inclusions, embedded in said single-crystal matrix, wherein
  • A is selected among I and CI;
  • C is selected among Ca, Sr, Ba and Mg, preferably among Sr and Ca;
  • X is selected among F, CI, Br, I and combinations thereof;
  • Y is selected among F, CI, Br, I and combinations thereof;
  • a, b, x, v, y, w and z are molar indices for LiX, NaY, A, C, Li, Na and Ce, respectively.
  • Embodiment 2 The material according to embodiment 1 , having a formula selected among:
  • La(Bri- x Ax)3:Ce:C-(LiX) a C being selected among Ca, Sr, Ba and Mg, preferably being Sr; Ce(Bri- x Ax) 3 -(LiX) a ;
  • Ce(Bri xA x )3:C-(LiX)a C being selected among Ca, Sr, Ba and Mg.
  • Embodiment 3 The material according to embodiment 1, where the single-crystal matrix is selected among LaBr3:Ce, LaBr3:Ce:Sr, CeBn and CeBr3:Ca.
  • Embodiment 4 The material according to embodiment 1 , having the formula LaBr3:Ce-(LiBr) a .
  • Embodiment 5 The material according to any one of the preceding embodiments, where more than 10 weight % of the Li is under the form 6 Li.
  • Embodiment 6 The material according to the immediately preceding embodiment, where more than 50 weight % of the Li is under the form 6 Li.
  • Embodiment 7 The material according to any one of the preceding embodiments, characterized in that x is less than or equal to 0. 10, preferably less than or equal to 0.04, preferably less than or equal to 0.03, more preferably zero; and/or v is greater than 0.001 , and/or less than or equal to 0.05, preferably less than or equal to 0.004, more preferably less than or equal to 0.003; and/or a is greater than 0.01, preferably greater than or equal to 0.05, and/or less than or equal to 0.2, preferably less than or equal to 0. 18.
  • a process for manufacturing a material according to any one of the preceding embodiments can include the following successive steps: preparing a starting charge having a composition suitable to the composition of said material; synthesizing the composite single crystal, from the starting charge, by a vertical gradient crystallization method or by Edge Defined Film Fed Growth method, the starting charge comprising a first flux providing lithium Li and of formula LiX, X being selected among F, CI, Br and I.
  • Embodiment 10 The process according to the immediately preceding embodiment, where X is the element Bromine Br.
  • Embodiment 11 The process according to any one of the two immediately preceding Embodiments, where the amount of said first flux is greater than 1%, preferably greater than 3%, more preferably greater than 4%, and/or less than 10%, preferably less than 8%, more preferably less than 6%, by weight percentage based on the starting charge.
  • Embodiment 12 The process according to any one of the two immediately preceding embodiments, where the starting charge comprises a second flux, the second flux supplying iodine I, and preferably being Nal.
  • Embodiment 13 Use of a material according to any one of embodiments 1 to 8 or manufactured according to any one of embodiments 9 to 12, as a component of a scintillation detector, in particular for applications in industry, the medical field and/or the detection for oil drilling.
  • Embodiment 14 Security detector, in particular for the identification of objects, can include a material emitting both gamma radiation and thermal neutrons, in particular of illicit objects, comprising a material according to any one of embodiments 1 to 8 or manufactured according to any one of embodiments 9 to 12.
  • Embodiments as described in this specification can allow for relatively large radiation detectors that can be used for inspecting cargo, vehicles, or other large objects, as well as research on high energy physics, medical imaging, small detectors, network communications, broadcast receivers, wireless transmissions, augmented reality devices, and broadcasting networks. Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed is not necessarily the order in which they are performed.
  • a composite single crystal was produced using a Bridgman method of vertical synthesis adapted by adding a flux containing Li, as follows:
  • a starting charge was first prepared by mixing the following powders: LaBra - 845.2 g CeBra - 44.6 g LiBr - 10.2 g
  • the vertically arranged ampoule 12 comprised a cylindrical part 14, with an internal diameter of 33 mm and a length of 345 mm, extended downwards by a conical part 16, whose angle at the top was 60°, defining the ampoule bottom.
  • the internal volume of the ampoule is estimated at 300 ml.
  • the ampoule 12 also comprised a quartz pocket 18 located at the bottom of the ampoule.
  • the mixture of powders making up the starting charge 19 was then poured into the ampoule, through a top opening 20.
  • the pressure was then reduced to less than 10" 2 mbars in the ampoule, and the ampoule was immediately sealed, by plugging the top opening 20 with an acetylene-oxygen flashlight, to prevent oxidation and volatilization.
  • the ampoule 12 was then placed on an ampoule holder 22 inside a Bridgman furnace 24 of the type shown in figure 4.
  • the furnace interior 24 comprised a lower "cold” zone 26, an intermediate gradient zone 28 and an upper "hot” zone 30.
  • the intermediate zone was defined by a horizontal wall 32 separating the hot and cold zones ("baffle").
  • the furnace 24 comprised also electric resistors to heat the different zones to different temperatures.
  • the ampoule holder 22 has been placed in the furnace interior so that the starting charge is in the hot zone 30 and half of the seed 10 is in the cold zone 26 and the other half of the seed is in the intermediate zone and in the hot zone.
  • the setpoint temperature of the oven in the hot zone was set at 850°C to melt the charge in the ampoule and the upper part of the seed 10.
  • the temperature in the cold zone was controlled so as not to exceed 770°C and not to melt the lower part of the seed.
  • the ampoule was moved downwards for three weeks, at a speed of 0.5 mm/h, corresponding to the crystallization rate, so that the solid-liquid interface remained in the hot zone. A crystal gradually formed in the lower part of the ampoule.
  • Figure 4 illustrates this synthesis operation.
  • the formed crystal 34 in the lower part of the ampoule, and the residual starting charge 19.
  • the ampoule was then gradually cooled at a rate of 10°C/hour to room temperature of
  • the ampoule was then cut open using a circular saw fitted with a diamond blade, in a glove box so as not to expose the resulting crystal to moisture after removal from the ampoule.
  • the crystal On leaving the ampoule, the crystal consists of five parts, namely, successively from bottom to top:
  • the cylinder trunk made of a material according to the invention constitutes a composite single crystal according to the invention, rich in Li and 6 Li due to progressive Li segregation during growth.
  • Example 2 The other examples were manufactured in a similar way to Example 1, adapting the composition of the starting filler.
  • Table 1 summarizes the compositions of the starting charge and the corresponding material according to the invention.
  • the factors indicate mass percentages.
  • “0.95Lao,95 Ceo.os Br3 + 0.05LiBr” means that the starting charge comprises 5% flux and 95% other powders, in mass percentage based on the starting charge.
  • the indices are also atomic percentages.
  • Examples 3, 6, 9, 11 and 12 are particularly advantageous because they use a second flux, which is not a REI3 flux, where RE stands for rare earth, to achieve a partial anionic substitution of Br (or Cl) by iodine I.
  • REI3 salts are known to be very hygroscopic.
  • the manufacturing conditions are facilitated.
  • the addition of I (Iodine) by a flux advantageously moves the main scintillation emission peak closer to the spectrum of wavelengths to which photomultiplier tubes are most sensitive.
  • substituting Br with I shifts the scintillation emission peak from 380-390 nm to 420 nm. This makes Nal and Lil fluxes particularly advantageous, as Lil can advantageously supply both Li and I.
  • Example 3 advantageously presents a reduced afterglow, as shown in Figure 6.
  • This figure shows after gamma-ray irradiation the afterglow (normalized signal) of crystals LaB (Ce) - B380 (intermediate region, dark gray), LaBr3:Ce:Sr - B390 (upper region, black) and LaBrs (Ce,Li) (lower region, light gray), as a function of time (x-axis, ns).
  • the level of afterglow or crystals synthesized with a Lil flux is advantageously reduced, making it possible, for example in the case of repeated detections, e.g., of baggage image acquisition in an airport gantry, to improve the sharpness of these images.
  • Example 1 The single crystal of Example 1 was cut in two, and each part of the initial single crystal, with a volume of 18.5 cm 3 , was encapsulated in the form of a conventional "geoline" assembly, i.e., mounted in a blind metal tube whose opening was conventionally sealed with a transparent membrane.
  • a conventional "geoline” assembly i.e., mounted in a blind metal tube whose opening was conventionally sealed with a transparent membrane.
  • the detectors were exposed to the same neutron source 252 Cf and an energy spectrum was determined from the light signal returned by the detectors.
  • Figure 2 shows the spectrum obtained for the first detector, the spectrum obtained with the second detector being similar.
  • Each detector was then exposed to a source of 137 Cs so as to receive gamma radiation at 662 keV.
  • the energy spectra obtained were analyzed to determine the energy resolution (PHR) for the two largest peaks representing the response to gamma radiation.
  • a scintillator material according to the invention enables a detection of both gamma rays and thermal neutrons, with an energy resolution value (PHR), determined at 662 keV, of less than 3.0%.
  • PHR energy resolution value
  • Figure 5 illustrates the measurement of the FoM for the discrimination of gamma rays and thermal neutrons using the PSD (Pulse-Shape-Discrimination) method. It shows the PSD parameter (head/total) as a function of energy, in keV. The upper scatterplot represents the contribution of thermal neutrons. The lower scatterplot represents the contribution of gamma rays. The right-hand side shows the density of points in the framed region of interest.
  • PSD Peak-Shape-Discrimination
  • the FoM was measured for both detectors. Tn both cases, it was 1 .2, confirming a good discrimination capability.
  • the FoM was also measured for a detector manufactured as described above, with a scintillator material manufactured as in Example 1 , but with lithium enriched in 6 Li so that the atomic ratio in 6 Li/( 6 Li+ 7 Li) is 95%. This was 1.66, showing that an increase in 6 Li content further improves discrimination capability.

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  • Organic Chemistry (AREA)
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  • Crystallography & Structural Chemistry (AREA)
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  • Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • General Engineering & Computer Science (AREA)
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  • Crystals, And After-Treatments Of Crystals (AREA)
  • Measurement Of Radiation (AREA)

Abstract

Un matériau scintillateur inorganique sous la forme d'un monocristal composite est divulgué. Le cristal peut avoir une formule comprenant La1-z-vCezCv(Br1-xAx)3-v+y+wLiyNaw-(LiX)a-(NaY)b consistant en une matrice monocristalline La1-z-vCezCv(Br1-xAx)3-v+y+wLiyNaw et de LiX, et éventuellement des inclusions de NaY, incorporées dans ladite matrice monocristalline. A peut être choisi parmi I et Cl ; C peut être choisi parmi Ca, Sr, Ba et Mg, de préférence parmi Sr et Ca ; X peut être choisi parmi F, Cl, Br, I et des combinaisons de ceux-ci. Y peut être choisi parmi F, Cl, Br, I et des combinaisons de ceux-ci. 0 ≤ x ≤ 0,5 ; 0 ≤ y ≤ 0,02 ; 0 ≤ v ≤ 0,1 ; 0 ≤ w ≤ 0,02, de préférence w = 0 ; 0 ≤ z ≤ 1 ; 0 ≤ z +v ≤ 1 ; 0 < a ≤ 0,20 ; 0 ≤ b ≤ 0,20 ; a, b, x, v, y, w et z peuvent être des indices molaires pour LiX, NaY, A, C, Li, Na et Ce, respectivement.
PCT/US2023/081607 2022-11-29 2023-11-29 Matériau scintillateur et procédé de fabrication Ceased WO2024118778A1 (fr)

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US20140319362A1 (en) * 2010-01-28 2014-10-30 Canon Kabushiki Kaisha Scintillator crystal body, method for manufacturing the same, and radiation detector
JP2017149883A (ja) * 2016-02-26 2017-08-31 国立大学法人東北大学 シンチレータおよび放射線検出器
WO2021229132A1 (fr) * 2020-05-14 2021-11-18 Consejo Superior De Investigaciones Cientificas (Csic) Dispositif de détection, d'identification, de quantification et/ou de localisation simultanée de sources de rayonnement gamma et de neutrons
CN114180845A (zh) * 2021-11-22 2022-03-15 东北大学 一种金属卤化物闪烁体微晶玻璃材料、制法及其应用

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NL1014401C2 (nl) 2000-02-17 2001-09-04 Stichting Tech Wetenschapp Ceriumhoudend anorganisch scintillatormateriaal.
EP1553430A1 (fr) 2004-01-09 2005-07-13 Stichting Voor De Technische Wetenschappen Scintillateur pour neutrons thermiques avec rendement lumière elevé
EP2718398A4 (fr) 2011-06-06 2014-12-03 Saint Gobain Ceramics Cristal de scintillation comprenant un halogénure des terres rares et système de détection de rayonnement comprenant le cristal de scintillation
DE112012003524T5 (de) * 2011-09-22 2014-06-12 Saint-Gobain Cristaux Et Detecteurs Ein Seltenerdelement enthaltende Szintillationsverbindung und ein Verfahren zu deren Herstellung
JP6563339B2 (ja) * 2013-10-28 2019-08-21 株式会社トクヤマ 中性子シンチレーター、中性子検出器及び中性子シンチレーターの製造方法

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US20130214145A1 (en) * 2009-05-22 2013-08-22 Schlumberger Technology Corporation Gamma-Ray Detectors For Downhole Applications
US20140319362A1 (en) * 2010-01-28 2014-10-30 Canon Kabushiki Kaisha Scintillator crystal body, method for manufacturing the same, and radiation detector
JP2017149883A (ja) * 2016-02-26 2017-08-31 国立大学法人東北大学 シンチレータおよび放射線検出器
WO2021229132A1 (fr) * 2020-05-14 2021-11-18 Consejo Superior De Investigaciones Cientificas (Csic) Dispositif de détection, d'identification, de quantification et/ou de localisation simultanée de sources de rayonnement gamma et de neutrons
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