[en] A new technique of Se mass spectrometry has been developed and applied to the isotopic analysis of electromagnetically enriched isotopes of Se produced in the INS Mass Separator. Se⁺-ions were effectively produced from PbSeO₄ using a modified ion source designed for the analysis of a few micro grams of sample aliquot. Stable ion current of 10^-17 A for Se⁺-ion was obtained and this technique was found to be applicable to routine isotope ratio measurements. With this ion source equipped in the INS Mass Spectrometer, isotopic analysis was carried out with a standard deviation of <= 1% for the ion currents of >= 10^-17 A. For the measurements of low intensity beam ( -- 10^-18 A) there arose additional errors due to the instrumental instability of the background noise and, in some cases, to the contribution of the hydrocarbon background from the impurities of the sample. (auth.)

[en] A large-area, high-resolution two-dimensional position sensitive gas detector has been developed for intermediate energy heavy ions. The x position information is obtained by a multi-cathode read-out method and the y position by measuring the drift time of electrons. This detector has no left-right ambiguity and very little dead layer in the sensitive area, resulting in a detector system which is thin and homogeneous in the whole sensitive area. The overall position resolution of 0.20 mm and 0.4 mm (FWHM) were obtained for x and y directions, respectively. The position resolutions at lower gas pressure were also measured to find an optimum operating condition to reduce multiple scattering effect from the window foils and the detector gas. This detector has been shown to be very useful for high-resolution heavy ion experiments at intermediate energies. (author)

[en] A large-area, high-resolution two-dimensional position sensitive gas detector has been developed for intermediate energy heavy ions. The x position information is obtained by a multi-cathode method and the y position by measuring the drift time of electrons. This detector has no left-right ambiguity and no dead layer in the sensitive area as like a multi wire drift chamber, resulting in a detector system which is thin and homogeneous in the whole sensitive area. The overall position resolutions of 0.22 mm and 0.40 mm (FWHM) were obtained for x and y directions, respectively. This detector system has been shown to be very useful for high-resolution heavy ion experiment at intermediate energies. (author)

[en] A review of the epitaxial silicon semiconductor detectors and our proposals are presented. Calculations of the potential and electric field distributions in the N⁺-N(or N-N⁺) complex structure are also performed. (author)

[en] 01 XX The chemical preferential etching technique is applied on fabrication of thin silicon detectors with uniform thicknesses. For this purpose, the silicon epitaxial wafers which have high resistivities and uniform impurity profiles with abrupt interfaces between epitaxial layers and substrates are required. Crystal growth techniques used for satisfying these requirements are described. Chemical etching processes employed for performing uniform dissolution of the substrate and for maintaining a large difference of etching rates in low and high resistivity silicon layers are also described. The donor impurities doped in substrates are antimony (Sb) and arsenic (As). The effects of impurities upon the fabrication of detectors are discussed considering the characteristics of these dopants. 7 refs

[en] Levels in ²²Mg between 4 and 7 MeV excitation energy have been populated in a high-resolution study of the ²⁴Mg(p,t)²²Mg reaction. Two new states have been observed at energies E_x=5090 and 6323 keV, while two states were observed at 5962 and 6046 keV. The precision in measured excitation energies for several other ²²Mg levels has been improved substantially. In addition, a new state at 8141 keV was observed in ²³Mg. Using spin and parity restrictions from the present and previous work, we discuss T=1 analog state assignments of A=22 nuclei below 7 MeV excitation energy. The implications for the rate of the stellar reaction ²¹Na(p,γ)²²Mg which takes part in hydrogen burning during nova outbursts are presented

[en] A chemical etching technique is applied to the fabrication of a thin silicon detector with a uniform thickness. The chemical etching has many advantages compared with the electrochemical etching, although good crystals which have high resistivity silicon layers epitaxially grown on heavily doped substrates are required for this purpose. (Auth.)

[en] A focal-plane counter for a magnetic spectrometer was fabricated using a large, home-made silicon detector as an energy counter for particle identification. The resolution of the particle identification was tested by measuring rarely-happening ⁸He particles in an environment of a large background of other particles. High-resolution energy signals from the silicon detector were essential for the background reduction. The silicon detector covered an energy range as wide as 5.5%. (orig.)

[en] A large enhancement of the ¹³C(α,n)¹⁶O reaction cross section at low energy limit due to the sub-threshold state in ¹⁷O has been predicted, explaining the neutron source of s-process nucleosynthesis. By the ¹³C(⁶Li,d)¹⁷O transfer reaction, we had deduced the resonance strength of the state. Contrary to the predictions, the sub-threshold state was found to have very small contribution to the astrophysical S factor

[en] For the radioactive nuclear beam facility at KEK Tanashi based on an isotope separator on-line (ISOL), two different types of ion sources are currently employed: a single stage 6.4 GHz ECR and a surface ionization-type ion sources. Several proton-rich radioactive nuclear beams were developed for astrophysical interests. LiF powder target in a water-cooled Cu container is used for the production of Ne isotopes and CaF₂ mixed with fine graphite powder for Na isotopes. The ion beams are bunched at the exit of the ion source in order to reduce the beam loss in post acceleration