A new conversion screen Gd₂O₂S:Eu has been developed which emits red light on thermal neutron irradiation. By using this in combination with the current green-light scintillator (Gd₂O₂S:Tb) in radiography under a neutron ＋ X-ray field, we can easily separate the neutron and the X-ray images on PC with any color-graphic software in the market. This technique leads us to a new possibility of non-destructive and high-precision inspection of industrial products composed both of light elements (organic compounds and plastics) and heavy elements (metals).

  Characteristics of various functional dyes and related compounds for a chemical radiochromic dosimeter are outlined. Chemical radiochromic dosimeters using new functional leuco dyes and high sensitive acid generators dissolved in chloroform and ethanol can be used over the absorbed dose range in 0.1-30 Gy. Plastic films with dissolved those dyes and functional materials, and with microcapsules included leuco dyes and organic solvent are applied to the routine dosimeter for the measurements of absorbed doses of γ-irradiation (60Gy-1.2KGy), which is potentially useful for food and blood irradiation fields.

  We observed photostimulated luminescence and long-lasting phosphorescence phenomena in rare-earth-ion-doped glasses. The mechanisms of the phenomena were discussed. These glasses may be promising materials for two-dimensional imaging sensors of radiation.

  Two dimensional color patterns of radiation-induced luminescence, including after-glow color images (AGCI) and thermoluminescence ones (TLCI), have been conveniently photographed for some rock slices by means of a commercially available negative color film after the irradiation of X- or γ-rays. Both color images (AGCI and TLCI) offered very interesting images; the constituent minerals showed distinctly separable color patterns in which the same minerals were giving different stripe patterns of luminescence intensities in each other and even within the one mineral grain. In the case of quartz grains, pure red TL images from volcanic origins have been initially found in addition to the well-known blue TL quartzes. It was assumed that the conditions of crystal formation and subsequent metamorphosis should be greatly affected on these luminescence images. The present simplified luminescence images are considered to be preferable for the practical application of luminescence phenomena onto the material sciences, geological fields, nuclear and archaeological sciences, and so on. Some recent applications of the luminescence have been described from aspects of utilization of accumulated dosimeter.

  Subsequently, a constraction of an automatic luminescence measuring system incorporated a small X-ray generator, involving both TL and OSL (Optically Stimulated Luminescence), is also described.

  The detection characteristic of long lasting phosphor (LLP, SrAl₂O₄ ; Eu²⁺, Dy³⁺) has been studied in α, β, and γ radiation field. It was found that the total luminous intensity of LLP had linear response over a wide range of absorbed energy for all radiations. The luminous intensity showed significant temperature dependence and the peak intensity was observed near room temperature. The thermoluminescence glow curve suggested that the luminosity of LLP consisted of 4-components and the time profile of LLP luminescence was found to be described by a simple sum of these components. The Arrhenius plot of escape rates calculated from the afterglow region provided the activation energies of escape process form trap levels and these values were ranged from 24 meV to 0.34 eV, which corresponded to the escape rates of 0.8-8.3 x 10³ s^-1 at room temperature. The trapping ratios to the 4 traps were also determined from afterglow ratio curves and had no temperature dependence. These trapping ratios were ranging from 0.16 to 0.35 for β and γ irradiation and slightly different values were obtained for α rays. The experimental time profile can be fitted within experimental error using the trapping ratios and escape rates. Various applications of LLP will be expected as radiation detectors, especially as 2-dimensional imaging devices.

  The production of acoustic radiation by electrons traversing water has been investigated. The acoustic detectors used in the experiment were made from piezoceramic compounds. The acoustic pressure signal was a simple bipolar pulse and the amplitude was proportional to the total energy deposition. Characteristic properties for detecting acoustic signals using an electron beam pulse are described. Some results are presented on the detector performance.

  The quantities for ionizing radiation (e.g. fluence, exposure, and absorbed dose) are defined as non-stochastic quantities so that they correspond to values at a point in space. They can be calculated or estimated as the expectation value, i.e. the average, of the associated stochastic quantities. These points are not distinguished in most of the textbooks for radiation measurements and dosimetry. This can lead to misunderstanding of the concepts of the quantities. The definitions and concepts for absorbed dose and fluence are described in detail.

  A tandem detector, which positively raises directional dependence for coming gamma-rays, has been developed for simultaneous measurement of directions and energies of coming gamma-rays. The detector has optically combined a cylindrical NaI(Tl), the same sized BGO scintillator and a fitted photomultiplier tube at this order. Since lengths of crossing each scintillator are changed according to coming directions of gamma-rays, directions can be recognized by counting photopeaks on a spectrum made by the NaI(Tl) and the BGO scintillator and by obtaining the ratio of photopeak counts. It is also clear that energies can be easily measured, which are proportional to channels of photopeaks on the spectrum derived from the detector.