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AssigneesTokuyams Corporation, Tohoku University
InventorsAkira Yoshikawa, Takayuki Yanagida, Kentaro Fukuda, Sumito Ishizu, Noriaki Kawaguchi, Toshihisa Suyama
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A scintillator for neutron detection, comprising a metal fluoride crystal containing, as constituent elements, a metal having a valence of 2 or higher, such as calcium, aluminum or yttrium; lithium; and fluorine, the metal fluoride crystal containing 1.1 to 20 atoms per unit volume (atoms/nm3) of 6Li, having an effective atomic number of 10 to 40, containing a lanthanoid such as cerium, praseodymium or europium, and being represented by, for instance, LiCaAlF6, LiSrAlF6 and LiYF4. The scintillator for neutron detection has high sensitivity to neutron rays, and is reduced in a background noise attributed to γ rays.
A scintillator for neutron detection, comprising a metal fluoride crystal containing lithium, a metallic element having a valence of 2 or higher, and fluorine as constituent elements, said metal fluoride crystal containing 1.1 to 20 atoms per unit volume (atoms/nm3) of 6Li, having an effective atomic number of 10 to 40, and containing a lanthanoid.
Dependencies are inferred from the claim text.
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Measuring neutron radiation: with scintillation detectors
Halogenides: with alkali or alkaline earth metals
Conversion screens for the conversion of the spatial distribution of x-rays or
Measurement of nuclear or x-radiation
About 2 years 5 months of term left · ends 17 Mar 2029 (estimated)
This invention relates to a scintillator for neutron detection which is used for detecting neutrons. More particularly, the invention relates to a scintillator for neutron detection which is composed of a metal fluoride crystal containing a lanthanoid.
A scintillator is a substance which, when hit by radiation such as α rays, β rays, γ rays, X-rays, or neutron rays, absorbs the radiation to emit fluorescence. The scintillator is used for radiation detection in combination with a photodetector, such as a photomultiplier tube, and has wide varieties of application fields such as the medical field, for example, tomography, the industrial field, for example, nondestructive inspection, the security field, for example, inspection of personal belongings, and the scientific field, for example, high energy physics.
Among the scintillators are various types of scintillators available according to the types of radiation and the purposes of use. They include inorganic crystals such as Bi4Ge3O12, Gd2SiO5:Ce, PbWO4, CsI, and KI, organic crystals such as anthracene, fluorescent substance-containing polymers such as polystyrene and polyvinyltoluene, and special scintillators including liquid scintillators and gas scintillators. When neutron rays are the object of detection, they are generally detected by utilization of a nuclear reaction which converts neutrons promptly into charged particles having energy, since neutrons have strong power to pass through a substance without performing any interaction in the substance.
FIG. 1 is a pulse-height spectrum by scintillators for neutron detection according to the present invention.
FIG. 2 is a pulse-height spectrum by the scintillator for neutron detection according to the present invention.
FIG. 3 is a schematic view of a crystal manufacturing apparatus by the micro-pulling-down method which is used for the scintillator of the present invention.
Description of the Reference Numerals 1 After-heater 2 Heater 3 Heat insulating material 4 Stage 5 Crucible 6 Chamber 7 High frequency coil 8 Pulling-down rod 9 Scintillator for neutron detection 10 Photodetector
The scintillator for neutron detection according to the present invention comprises a metal fluoride crystal containing lithium, a metallic element having a valence of 2 or higher, and fluorine, the metal fluoride crystal also containing a lanthanoid. The metal fluoride crystal is a lithium-containing metal fluoride crystal characterized maximally by having a specific 6Li content and a specific effective atomic number, and containing a lanthanoid. In the present invention, the term “metal fluoride crystal” refers to a crystal containing all of the above-mentioned components, whereas the term “matrix metal fluoride crystal” refers to a crystal comprising components other than the lanthanoid.
In the present invention, the above-mentioned 6Li content refers to the number of Li elements contained in 1 nm3 of the scintillator. Incident neutrons cause a nuclear reaction with this 6Li to generate α rays which are secondary radiation. Thus, the 6Li content affects sensitivity to neutron rays, and the higher the 6Li content, the higher the sensitivity to neutron rays becomes.