Shouichi Nasu

Eu‐doped KCl phosphor crystals as a storage material for two‐dimensional ultraviolet‐ray or x‐ray imaging sensors

Intense optically stimulated luminescence (OSL) with a peak at about 430 nm is observed in ultraviolet (UV)‐ray or x‐ray irradiated europium‐doped potassium chloride (KCl:Eu) phosphor crystals. The OSL intensity is increased with increasing UV‐ray or x‐ray irradiation dose. This suggests that KCl:Eu phosphor crystal is useful as a material for two‐dimensional UV‐ray or x‐ray imaging sensor utilizing OSL phenomenon. The results obtained are consistent with the proposed emission mechanisms of the 420 nm OSL peak, based on the recombination of electrons released from the F centers with Eu3+ ions. The excitation mechanism for the OSL in UV‐ray irradiated KCl:Eu phosphor crystals is also discussed.

A novel image storage sensor using photostimulated luminescence in SrS:Eu,Sm phosphor for electromagnetic waves such as X-rays, UV-rays and visible light

Abstract Intense photostimulated luminescence (PSL) with a peak at about 600 nm is observed in europium and samarium co-doped strontium sulfide (SrS:Eu,Sm) phosphor ceramics irradiated with electromagnetic waves such as X-rays, UV-rays or visible light. The PSL intensity increases linearly with increasing dose of electromagnetic waves. This result suggests that the SrS:Eu.Sm phosphor is useful as a material for a two-dimensional imaging sensor for electromagnetic waves using the PSL phenomenon.

Eu concentration dependence of photostimulated luminescence in X-ray or UV-ray irradiated KCl: Eu phosphor ceramics

Abstract Europium doped potassium chloride (KCl:Eu) phosphor ceramics for two-dimensional X-ray or UV-ray imaging sensor utilizing photostimulated luminescence phenomenon (PSL) were prepared. Investigation of Eu concentration dependence of the PSL in X-ray or UV-ray irradiated KCl:Eu phosphor ceramics was carried out. An intense PSL with a peak at about 420 nm was observed in 0.5 mol % Eu doped KCl phosphor ceramics which is fabricated by sintering at about 700°C in air.

Photostimulated luminescence in alkali halides induced by excitation with ionizing radiation

Abstract The photostimulated luminescence (PSL) phenomenon induced in copper-doped sodium chloride (NaCl:Cu) and europiumdoped potassium chloride (KCl:Eu) phosphor crystals by excitation with ionizing radiation such as X-rays is studied. The emission mechanism of the PSL in both phosphor crystals is discussed in terms of the recombination of electrons optically stimulated from the radiation-induced F centers with the luminescence centers such as Cu 2+ in NaCl and Eu 3+ ions in KCl. The potentiality of both phosphor crystals as a material for two-dimensional X-ray imaging sensors utilizing the PSL phenomenon is also discussed.

Advanced optical storage phosphor materials for erasable and rewritable optical memory utilizing photostimulated luminescence

The Boolean logic operations such as OR, AND and NOR are demonstrated using photostimulated luminescence (PSL) phenomenon in the imaging plate (IP) which is made by BaFBr:Eu photostimulable phosphor. The PSL in Eu and Sm co-doped SrS (SrS:Eu,Sm) phosphor ceramics is studied in order to develop a smart erasable and rewritable optical memory utilizing PSL phenomenon, because the SrS:Eu,Sm phosphor ceramics which are excited with UV-light or visible light exhibits an intense PSL, compared with that in UV-irradiated IP. Intense PSL with a peak at about 600 nm is observed in SrS:Eu,Sm phosphor ceramics which is stimulated with infrared light after irradiation with ultraviolet-(UV) light or visible-light. The PSL characteristics of SrS:Eu,Sm phosphor ceramics as a photostimulable material for the optical memory are reported.

Photostimulated luminescence in CaS: Eu,Sm phosphor ceramics induced by excitation with ionizing radiation

Intense photostimulated luminescence (PSL) with a peak at about 650 nm is observed in europium and samarium co-doped calcium sulfide (CaS: Eu,Sm) phosphor ceramics by excitation with ionizing radiation such as X-rays and UV-rays. The PSL intensity is increased by increasing the X-ray or UV-ray dose, indicating that CaS: Eu,Sm phosphor is a useful material for two-dimensional X-ray or UV-ray imaging sensor utilizing PSL. The results obtained are consistent with the proposed emission mechanism of the 650 nm PSL, based on the recombination of electrons released from Sm2+ ions as electron traps with Eu3+ ions.

New photostimulable phosphor materials for an imaging plate of computed radiography

The photostimulated luminescence (PSL) characteristics of alkali halide phosphors, such as KCl:Eu, KBr:Eu and KClxBr1-x:Eu phosphors, as new storage photostimulable phosphor materials for the imaging plate in computer radiography are investigated. Intense 420 nm PSL is observed in X-ray-irradiated KClxBr1-x:Eu phosphor. The PSL intensity increases linearly with increasing X-ray irradiation dose over the wide range, showing a good storage material for the imaging plate in computed radiography. The KBr:Eu phosphor exhibits excellent fading characteristics, which showing that the KBr:Eu phosphor is useful as a material for medical imaging utilizing PSL phenomenon. The mechanism of the fading is also discussed.

Eu-Doped KCl Storage Phosphor for Erasable and Rewritable Optical Memory Utilizing Photostimulated Luminescence Phenomenon

Intense photostimulated luminescence (PSL) with a peak at 420 nm is observed in ultraviolet (UV) Iight-irradiated europium-doped potassium chloride (KCl: Eu) crystalline phosphors. The PSL characteristics of UV-irradiated KCl: Eu phosphor for optical memory application were studied. The excitation and emission mechanisms of the 420 nm PSL, which are consistent with the results obtained, are discussed.

Photostimulated luminescence in CaxSr1-xS:Eu,Sm phosphor ceramics and its application to radiation dosimetry

It is demonstrated that the commercially-available imaging plate (IP) using BaFBr:Eu photostimulable phosphor is useful as a phosphore material for 2D UV image sensor though the sensitivity of the IP for UV-ray is not so high. The new phosphore materials as alternative materials for the IP are surveyed for many possible phosphore materials and consequently we find out that the CaxSr1-xS:Eu,Sm phosphore ceramics exhibited a high photo stimulated luminescence (PSL) intensity for UV-ray irradiation. It is found that the SrS:Eu,Sm phosphore ceramics exhibits good PSL characteristics for UV-ray imaging and the PSL characteristics are depended on the content of CaS and the concentration of Eu and Sm doped.

Novel two-dimensional IR image sensor utilizing photostimulated luminescence in II-VI compound phosphor ceramics

We found that an intense yellow photostimulated luminescence (PSL) can be observed when UV-light or visible-light irradiated SrS:Eu,Sm and CaS:Eu,Sm phosphor ceramics are estimated with IR light with wavelength from 800 nm to 1700 nm. This phenomenon in these phosphor materials is applicable to a novel 2D IR sensor. In the paper, we describe PSL characteristics in SrS:Eu,Sm and CaS:Eu,Sm phosphor ceramics, especially in SrS:Eu,Sm phosphor ceramics, and discuss the mechanism of the PSL which is observed by stimulating the phosphor with IR light.