[en] This issue is the collection of the paper presented at the title meeting. The 31 of the presented papers are indexed individually. (J.P.N.)

No abstract available

[en] In order to develop a high energy resolution x-ray microcalorimeter with fast response, we have fabricated a prototype of an Ir TES by a sputtering method. The very sharp superconductive transition of the prototype Ir TES was successfully obtained at the transition temperature of 188.3 mK. In the measurement of the 4 characteristics, the Ir TES showed an inverse proportional part of the Ir current against the bias voltage, which means the Ir TES is operating in the ETF mode. From these results, the performance of the x-ray microcalorimeter with the Ir TES can be estimated; the energy resolution of 1.3 eV (FWHM) and the effective time constant of 40 μsec are expected. Currently we are preparing a readout system of the microcalorimeter for an x-ray measurement. Theory of ETF-TES and preparation of the Ir-TES are described. (S.Y.)

[en] Through the measurement of ²²Na γ-rays, it has been demonstrated that the correction process was well done by fusing the similarity values with the pulse heights measured by the analog system, where at least four improvements in the energy spectrum characteristics were recognized, i.e., the increase of the peak-to-valley ratio, the photopeak area, the photopeak sharpness without discarding any events, and the 1,275 keV γ-ray photopeak was seen. The use of a slow digitizer was the main problem for this method. However, it can be solved easily using a faster digitizer. The fusion method was also applied for the beta-gamma mixed spectra separation. Mixed spectra of beta-gamma of the ¹³⁷Cs-⁹⁰Sr mixed source could be separated well. We made a comparison between the energy spectrum of ¹³⁷Cs as a result of independent measurement with the result of the separation. After being compared, both FWHM agreed quite well. However, there was a slight difference between the two spectra on the peak-to-valley ratio. This separation method is simple and useful so that it can be applied for many other similar applications. (S.Y.)

[en] As one of the application on digital waveform processing studies, a system that acquires digital waveform data by using digital oscilloscope have been constructed. As an example for measurement with this system, the decay times, pulse shape discrimination based on the pulse shape analysis and FWHM by the digital gated-integration method were measured. Pulse height analysis using digital oscilloscope is also effective similarly to measurements with MCA. Scintillation decay times derived for GSO and BaF₂ scintillator were reasonable to the known reference values. It is evident that the intensity of these two main decay components and their decay time depend on the Ce concentration in GSO scintillators. Concerning to the pulse shape discrimination its possibility was indicated in the observed difference in the fast and slow component of the signals from BaF₂ scintillator. The transfer rate from the digital oscilloscope to PC did not reach to the performance of the full rate of 200 Kbytes/s in the GP-IB standard. (S.Y.)

[en] We found that the effect of electric fields on deposit energy by electrons is obtainable from the electron range in a space with no electric field for low-energy electrons in weak electric fields. We calculated the effect of the electric field on the signal current from parallel-plate and cylindrical free-air ionization chambers by the EGS4 using an optional program for electric field and from the range of electrons in a space without an electric field. Photoelectrons emitted in a cylindrical ionization chamber gain or lose more than 0.3% of energy for photons with energy in a certain range. The net effect of the electric field for a signal current is usually small for both parallel-plate and cylindrical free-air ionization chambers because the gain and loss of energy usually compensate for each other. (S.Y.)

[en] In order to make useful detectors, which have high energy resolution and large sensitive area, we are going to develop detectors with p-type Si operated at low temperature (about 1 K). At 1 K, the w value of p-Si is 2 MeV. For the measurements of hole concentration, we have fabricated two types of devices: a single type device and a compound type device which consisted of two silicon wafers. The former type device is p-type silicon with 7 mm diameter and 0.5 mm thickness and 10¹³ cm^-3 boron density. The latter type devices consisted of a silicon wafer with higher boron density (H-Si) and one with lower boron density (L-Si). Boron density of H-Si and L-Si were 3 x 10¹³ cm^-3 and 8 x 10¹² cm^-3, respectively. From the results of single type device, holes were localized in non-depleted region by expanding depletion layer. The results of hole density measurement in compound type device showed that the hole density at 0 V was 1.24 X 10¹³ cm^-3. This means that the holes in H-Si were forced into L-Si. At the condition of very low temperature, the resistivity of silicon becomes higher, so that higher density silicon can be used as H-Si. (S.Y.)

[en] A green long lasting phosphor SrAl₂O₄:Eu²⁺, Dy³⁺ has been investigated for the radiation detection. It is shown that LLP (long lasting phosphor) has sensitivity to various radiations (alpha, beta and gamma ray) and the total phosphorescence intensity responses linearly in certain range of absorbed dose. Neutrons have not been surveyed in this study, but neutrons can be detected by using of LLP in principal if various converters for detection (Gd, polyethylene and so on) are used. The components of phosphorescence are confirmed four components. The delay constant of the fastest component is 0.59 and the slowest component does not appear in the accumulating process and is only observed in the afterglow process. It is confirmed that the phosphorescence efficiency of alpha ray has the great difference from that of beta or gamma ray. This difference is attributed to the difference of local charge density and initial recombination rate of charge pairs produced by the incident particle. (S.Y.)

[en] The fading characteristics and optical bleaching of the electron traps such as F(F^-), F(Br^-) and F(I^-) centers which are produced by X-ray irradiation are studied. Five kinds of the IP (imaging plate) (Fuji Photofilm) such as BAS-3, BAS-MS, BAS-ND, BAS-SR and BAS-TR were used as the samples. The samples were irradiated by X-rays from Cu-target tube operated at 40 kV and 20 mA. PSL (photostimulated luminescence) emission spectra and its stimulation spectra of samples were obtained. The experiments results showed the followings; 1) the fading of the X-ray image is remarkable in the longer wavelength, especially in the optical absorption band of the F(I^-) centers, 2) a part of electrons which are thermally or optically released from the electron traps centers such as F(Br^-) and F(I^-) centers are retrapped by the F(F^-) vacancies to produce the F(F^-) centers. (S.Y.)

[en] Rapid detection of fuel failures as well as failed fuel detection and location (FFDL) is quite important as safety instrumentation of fast reactors. As one of FFDL techniques, a tagging method was proposed. On the other hand, with recent improvement of laser performance, a resonance ionization mass spectrometry (RIMS) has been practicable. Now, authors proposed a new FFDL technique based on RIMS for the tagging method of fast reactors. RIMS needs a high vacuum chamber for the mass spectrometer. Therefore, authors proposed a gas injection method using pulsed supersonic valve (PSV) to densely inject gas into an ionization area. As a result of investigation, it was found that detection limit was improved to about six times by using PSV. And, as a result of simulation on behavior of an expanding gas jet into a vacuum chamber through PSV with numerical calculation based on hydrodynamics, it was concluded that distance should be as short as possible. (G.K.)