Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Kazuto Yokota

Naotoshi Matsuda

Masaaki Tamatani

Akihisa Saito

Noriaki Yagi

Miwa Okumura

Yukihiro Fukuta

Mitsuo Nakamura

A scintillator is disclosed that comprises a ceramic of a rare-earth oxysulfide activated with Pr, such as Gd.sub.2 O.sub.2 S:Pr, having: (1) a ratio of a peak value at about 270 K to that at about 140 K in a glow curve of about 0.01 or less, when the thermoluminescence intensity of the scintillator is measured at a rate of temperature increase of 15.+-.5 K/min after 20 minutes irradiation with ultraviolet rays having a wavelength of 254 nm and a power of 1 W/m.sup.2 at liquid nitrogen temperature, and (2) a ratio of a peak value at about 630 nm to that at about 512 nm of a thermoluminescence of about 410 K with about 2 nm resolution of about 1 or less.

Rare-earth oxysulfide scintillators and X-ray detectors using rare-earth

A fluorescent substance is comprised of a rare earth oxysulfide represented by the chemical formula, R.sub.2(1-x) Pr.sub.2x O.sub.2 S, wherein R stands for at least one member selected from the group consisting of Y, Gd, La, and Lu and x for a numerical value satisfying the expression, 5.times.10.sup.-5 .ltoreq.x.ltoreq.1.times.10.sup.-2, and has a linear absorption coefficient of not more than 6.0 cm.sup.-1 at 550 nm. And further fluorescent substance contains PO.sub.4 in an amount of not more than 100 ppm.

Fluorescent substance, method for production thereof, radiation detector

A single crystal of a compound comprises a single crystal of a compound at least part of components is of the above mentioned material decomposed at a temperature around the melting point, having a volume of 5 cc or more, and deviation of respective elements in a composition of the single crystal from the stoichiometric composition is within the range of .+-.5%. Also, a process for preparing a single crystal of a compound comprises the steps of deaerating and sealing powder of a starting material for the single crystal in a sealable capsule, sintering the powder by subjecting to heat treatment (HIP treatment) at a temperature 1/2 or higher of the melting point in terms of the absolute temperature while applying high pressure to a sealed material of the powder, deaerating and sealing the sintered body in a sealable capsule made of a similar high melting point substance and having an inner shape corresponding to the shape of the sintered body, and preparing a single crystal by subjecting a sealed material of the sintered body to heat treatment at a temperature of the melting point of the starting material of the single crystal under pressure. As the single crystal of a compound, high quality single crystals with a large size such as RE.sub.2 O.sub.2 S or REVO.sub.4 (RE is a rare earth element) can be obtained.

Single crystal of compound, laser rod, laser oscillator, scintillator,

A single crystal of a compound comprises which easily decomposes at a temperature around the melting point and evaporates at least a part of the compound having a volume of 5 cc or more and a composition deviation of respective elements from the stoichiometric composition of the compound being within the range of .+-.5% in terms of weight ratio. Also, a process for preparing a single crystal of a compound comprises the steps of deaerating and sealing powder of a starting material for the single crystal in a sealable capsule, sintering the powder by subjecting to heat treatment (HIP treatment) at a temperature 1/2 or higher of the melting point in terms of the absolute temperature while applying high pressure to a sealed material of the powder, deaerating and sealing the sintered body in a sealable capsule made of a similar high melting point substance and having an inner shape corresponding to the shape of the sintered body, and preparing a single crystal by subjecting a sealed material of the sintered body to heat treatment at a temperature of the melting point of the starting material of the single crystal under pressure. As the single crystal of a compound, high quality single crystals with a large size such as RE.sub.2 O.sub.2 S or REVO.sub.4 (RE is a rare earth element) can be obtained.

An X-ray detector has a transmission type intensifying screen provided on the X-ray incident area of the detector body and a reflection type intensifying screen provided on the inner wall surface of the detector body except for the X-ray incident area. Visible rays from the transmission type intensifying screen and the reflection type intensifying screen are detected by a photomultiplier installed in the detector body. The transmission type intensifying screen and the reflection type intensifying screen use fluorescent materials such as Gd.sub.2 O.sub.2 S:Tb; Gd.sub.2 O.sub.2 S:Tb, Ce; GD.sub.2 O.sub.2 S:Tb, Yb; Gb.sub.2 O.sub.2 S:Pr; BaFCl:Eu; BaFBr:Eu; La.sub.2 O.sub.2 S:Tb; La.sub.2 O.sub.2 S:Tb, Ce; La.sub.2 O.sub.2 S:Tb, Yb; La.sub.2 O.sub.2 S:Pr; Y.sub.2 O.sub.2 S:Tb; Y.sub.2 O.sub.2 S:Tb, Ce; Y.sub.2 O.sub.2 S:Tb, Yb; and Y.sub.2 O.sub.2 S:Pr.

X-ray detector and X-ray examination system utilizing fluorescent

Rare earth oxysulfide ceramic material prepared by covering the material with a foil of a metal selected from the group consisting of molybdenum, tungsten, platinum, and rhenium, sealing it into an airtight vessel of tantalum or niobium, and then subjecting it to a hot isostatic press process.

Rare earth oxysulfide ceramics

This invention concerns an intensifying screen using a phosphor capable of emitting light under X-ray excitation. This intensifying screen is characterized by the fact that the phosphor layer in the intensifying screen comprises a first phosphor layer containing a phosphor represented by the general formula (I):

X-ray intensifying screen

There is provided a method of manufacturing a ceramic, wherein a ceramic material is covered with a foil of a metal selected from the group consisting of molybdenum, tungsten, platinum, and rhenium, sealed into an airtight vessel of tantalum or niobium, and then subjected to a hot isostatic press process. The method of the present invention can suppress coloration produced in the hot isostatic press.

Method of manufacturing a rare earth oxysulfide ceramic

A radiographic intensifying screen having improved modulation transfer function and/or sensitivity. The radiographic intensifying screen of the present invention comprises a support, a phosphor layer formed on the support, a protective film formed on the phosphor layer, wherein the phosphor layer includes a small phosphor particles layer at its support side consisting essentially of small phosphor particles with an average grain size of about 4 .mu.m or less and a binding agent; and a mixed large and small phosphor particles layer at its protective film side consisting essentially of large phosphor particles with an average grain size ranging from about 7 to 20 .mu.m, small phosphor particles present in the interstices of the large phosphor particles and with an average grain size of about 4 .mu.m or less and a binding agent.

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Yokohama, Japan

Kazuto Yokota