Hitachi Chemical Company, Ltd.

Hitachi, Ltd.

Hamamatsu-Photonics K.k.

National Institute of Radiological Sciences

Hiroyuki Ishibashi

Keiji Sumiya

Kazuhisa Kurashige

Naoaki Shimura

Shigenori Shimizu

Tatsuya Usui

Nachimuthu Senguttuvan

Yasushi Kurata

Kenzo Susa

Seikichi Akiyama

Akihiro Gunji

Kazushi Shimizu

Masato Yoshida

Shigeki Hirasawa

Takaji Yamashita

Masato Ikegawa

Hideo Murayama

Jeffrey S Schweitzer

Tomohide Omura

Naoko Inadama

Charles L Melcher

Kazuhiro Yoshida

Masahiro Aoshima

Kenzou Susa

Mitsuru Ishii

Mitsushi Kamada

Shinzou Kubota

Takeshi Utsu

Senguttuvan Nachimuthu

Provided are a crucible which prevents polycrystal formation to easily allow growth of optical part material single crystals, and a single crystal growth method employing the crucible. The crucible has a smooth surface of about Rmax 3.2 s as the surface roughness of the wall surfaceH, concave curved planeJ, cone surfaceF and convex curved planeL of the starting material carrying sectionD and the wall surfaceK of the seed carrying sectionE, which constitute the inner surface of the crucible of a crucible bodyA.

Crucible and single crystal growth method using crucible

A scintillator crystal represented by the following general formula (1).LnCeX:M&#x2003;&#x2003;(1)wherein LnCeXrepresents the chemical composition of the matrix material, Ln represents one or more elements selected from the group consisting of rare earth elements, X represents one or more elements selected from the group consisting of halogen elements, M is the constituent element of the dopant which is doped in the matrix material and represents one or more elements selected from the group consisting of Li, Na, K, Rb, Cs, Al, Zn, Ga, Be, Mg, Ca, Sr, Ba, Sc, Ge, Ti, V, Cu, Nb, Cr, Mn, Fe, Co, Ni, Mo, Ru, Rh, Pb, Ag, Cd, In, Sn, Sb, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl and Bi, and y represents a numerical value satisfying the condition represented by the following inequality (A):0.0001&#x2266;y&#x2266;1&#x2003;&#x2003;(A).

Scintillator crystal and radiation detector

The inorganic scintillator of the invention is an inorganic scintillator capable of producing scintillation by radiation, which is a crystal comprising a metal oxide containing Lu, Gd, Ce and Si and belonging to space group C2/c monoclinic crystals, and which satisfies the condition specified by the following inequality (1A), wherein Arepresents the number of Lu atoms in the crystal and Arepresents the number of Gd atoms in the crystal.{/()}&#x3c;0.50&#x2003;&#x2003;(1A)

Inorganic scintillator and process for its fabrication

Provided are a crucible which prevents polycrystal formation to easily allow growth of optical part material single crystals, and a single crystal growth method employing the crucible. The crucible has a smooth surface of about Rmax 3.2s as the surface roughness of the wall surfaceH, concave curved planeJ, cone surfaceF and convex curved planeL of the starting material carrying sectionD and the wall surfaceK of the seed carrying sectionE, which constitute the inner surface of the crucible of a crucible bodyA.

Crucible and method of growing single crystal by using crucible

An apparatus having a crucible () for holding a raw material, a heating means () for heating the raw material in the crucible () and a crystal transporting means () for transporting a seed crystal () upwards from the inside of the crucible (), which further comprises a heat conducting member () which extends upwards at least from the vicinity of the upper end of the crucible (), surrounds a single crystal () formed, and is made of a material having heat conductivity, and an interface portion radiation heat blocking member () for blocking, at least during cooling after the formation of a single crystal, the radiation heat toward an upper portion above the interface between a taper portion () of the formed single crystal () connecting with the seed crystal () and a straight bulge portion () having a cylindrical shape connecting with the taper portion () of the formed single crystal (). The use of the apparatus reduces the temperature difference in the radius direction of the single crystal (), resulting in the reduction of the occurrence of defects or cracks, which leads to the reduction of the fraction defective in production of single crystals.

Apparatus and method for producing single crystal

The inorganic scintillator of the invention is an inorganic scintillator capable of producing scintillation by radiation, which is a crystal comprising a metal oxide containing Lu, Gd, Ce and Si and belonging to space group C2/c monoclinic crystals, and which simultaneously satisfies the conditions specified by the following inequalities (1) and (2).{/()}&#x3c;0.50&#x2003;&#x2003;(1){/()}&#x2267;0.002&#x2003;&#x2003;(2)wherein Arepresents the number of Lu atoms in the crystal, Arepresents the number of Gd atoms in the crystal, and Arepresents the number of Ce atoms in the crystal.

Inorganic scintillator

The inorganic scintillator of the invention has the chemical composition represented by CeLnSiO(where Ln represents at least two elements selected from among Y, Gd and Lu. 0.001&#x2266;x&#x2266;0.1, 1.9&#x2266;y&#x2266;2.1, 0.9&#x2266;z&#x2266;1.1, 4.9&#x2266;u&#x2266;5.1) and emits fluorescence upon incidence of radiation, wherein the maximum peak wavelength in the intensity spectrum of the emitted fluorescence is a peak in the range between 450 nm and 600 nm.

Inorganic scintillator, and radiation detector and PET apparatus employing it

The present invention provides an inorganic scintillator including a matrix material comprising a metal oxide, and a luminescence center made of Ce contained in the matrix material, the inorganic scintillator being adapted to scintillate in response to a radiation; wherein the matrix material further comprises a dopant having a tetravalent ionization energy I [kJ&#xb7;mol] satisfying the condition represented by the following expression (1):3000&#x2266;I&#x2266;3500. &#x2003;&#x2003;(1)

This invention provides an inorganic scintillator capable of producing scintillation by radiation, which is a crystal comprising metal oxides including Lu, Gd, Ce and Si, which satisfies the condition specified by the following inequality (1A):0.0025&#x2266;{/()}&#x2266;0.025,&#x2003;&#x2003;(1A)and which has an absorption coefficient of no greater than 0.500 cmfor light with a wavelength of 415 nm.

When produced as a single crystal ingot, a rare earth silicate single crystalcan be formed by cutting out from the single crystal ingot. The single crystalhas a crystal face Fwhose Miller indices can be determined by X-ray diffraction. The crystal face Fis composed of a plurality of smooth partial region surfaces (for example, the partial region surface fA and partial region surface fB), the plurality of partial region surfaces each have an area detectable by X-ray diffraction, and the angles &#x3b8; formed between the normal vectors of the plurality of partial region surfaces satisfy the following inequality:0.1&#xb0;&#x2266;&#x3b8;&#x2266;2.0&#xb0;.&#x2003;&#x2003;(1)

Rare earth silicate single crystal and process for production of rare earth silicate single crystals

A depth of interaction detector with uniform pulse-height comprises a multi-layer scintillator obtained by coupling at least two scintillator cells on a plane and then stacking the planar coupled scintillator cells, in layers, up to at least two stages and a light-receiving element connected to the bottom face of each scintillator cell of this multi-layer scintillator, wherein the detector is provided with a means for discriminating the position of a scintillator cell, which receives radiant rays and emits light rays and a means for making, uniform, the quantity of the light emitted from each scintillator cell and received by the light-receiving element. The detector can provide precise detection information even when radiation is absorbed by and emitted from a scintillator layer positioned above the scintillator layer optically coupled to the light-receiving element, permits the production of a depth of interaction detector having a three-dimensional depth of interaction-detecting function and can provide the same total output signal, which is independent of the position or a specific scintillator cell practically emitting light if the radiation energy is identical.

Depth of interaction detector with uniform pulse-height

A single crystal of a silicate of a rare earth element herein provided is characterized in that it has a Ce concentration of not less than 0.6 mole % and not more than 5 mole % and that it has a light transmittance, as determined at a wavelength of 450 nm, of not less than 75%. The single crystal permits the solution of the problems associated with the conventional techniques or the problems concerning the coloration of the resulting single crystal and the reduction of the light transmittance thereof, which are disadvantages observed when the Ce concentration of the single crystal is increased to reduce the fluorescence-attenuation time. The single crystal thus permits the high-speed diagnosis of PET devices.

Single crystals of silicates of rare earth elements

A method of growing a rare earth silicate single crystal from a melt of a starting material containing a rare earth oxide and a silicon oxide, wherein the starting material in which a density of Fe as an impurity is not more 0.1 ppm, a density of Al as an impurity is not more than 0.4 ppm, or the starting material showing a weight loss of not more than 1.0% when heated up to 1,000.degree. C. is used. This method which makes it possible to stably obtain a rare earth silicate single crystal having a good scintillator performance, such as free of voids and/or non-colored crystals, or may cause no poor fluorescent characteristics due to a compositional deviation of materials.

Method of growing a rare earth silicate single crystal

A method of growing a crack-free single crystal is disclosed which comprises heating raw materials in a crucible to thereby obtain a melt of the raw materials, contacting a lower end of a seed crystal with the melt and pulling the seed crystal to thereby grow a single crystal, and wherein the melt of the crucible flows from its surface toward its inner part inside the crucible by convection at a position locating outside a region where the growth of the single crystal occurs. This flow control can be achieved by, for example, surrounding the crucible with a heat insulation refractory composed of a pair of semicylindrical refractories disposed so as to provide a circular cross section with differently sized gaps. In the above-mentioned method, the seed crystal may be rotated during a shoulder growth in which the single crystal has its diameter increased from that of the seed crystal to a target diameter at a rotation rate greater than that during a subsequent cylindrical body growth. Further, in the above-mentioned method, during the shoulder growth, the single crystal may have a solid-liquid interface configuration changed from a convex toward the melt to a flatness or a convex toward the seed crystal.

Method of growing single crystal

A method of growing a single crystal of a rare-earth silicate is disclosed which comprises heating raw materials in a crucible to thereby obtain a melt of the raw materials, contacting a lower end of a seed crystal with the melt and pulling the seed crystal to thereby grow a single crystal, and wherein the pulling is conducted along an axis of pulling having a gradient of at least 30.degree. from the b-axis ([010] axis) of the single crystal and a gradient of at least 25.degree. from the c-axis ([001] axis) of the single crystal. The invention also provides a method of machining a single crystal of a rare-earth silicate into a cylindrical form, comprising grinding a cylinder whose axis is directed so as to have a gradient of 0.degree. to 65.degree. from the c-axis ([001] axis) of the single crystal. Further, the invention provides a single crystal of a rare-earth silicate machined into a configuration having at least one plane, wherein the plane most close to the (100) plane of the single crystal has a gradient of at least 5.degree. from the (100) plane.

Growing community of inventors

Hitachinaka, Japan

Hiroyuki Ishibashi