Present status of the accelerators of heavy-ions are reviewed and future prospects of them are briefly discussed. Several examples of application of these accelerators in various fields of research are given in relation to the description of interaction of heavy ions with matter.
A previous paper (E. Sakai: “Oyobuturi”, Vol. 38, No, 1 (1969), pp. 2-19) described the state of the art in the development of semiconductor detectors at the end of 1968. The present paper reports the progress performed since 1969. The items described are as follows ; status and problems in germanium crystals for man-ufacturing Ge(Li) detectors, the best energy resolution achieved by Ge(Li) and Si(Li) detectors, an explanation of pulse risetimes, slow pulses and their effect on the time resolution of various timing circuits for Ge(Li) detectors, the calculated and measured detection efficiency of Ge(Li) detectors, search of the appropriate standard sources for the efficiency determina-tion, a concept of figure of merit, results of a measurement of incident gamma-ray angular dependence of the detection efficiency, temperature dependence of the performance of Ge(Li) detectors, radiation damage study, the development of gamma-cameras for medical use, ultra-high resolution Si(Li) X-ray detectors, high-purity germanium detectors, and gamma-ray detectors made from compound-semiconductors such as GaAs, CdTe, Hglz, etc..
Internal stress in Ag, Au, Cu and Mo films prepared by low pressure plasma sputtering are measured during the deposition by a bending method, and the results are compared with those of evaporated films. At an early stage of film growth where the film is still discontinuous, tensile stress is gen-erated in the sputtered film in the same manner as in the evaporated film. At a later stage when the film becomes continuous, compressive stress is generated in the sputtered film while tensile stress remains in the evaporated film. The origin of the compressive stress is considered to be due to gas incorporation from the investigation of the correspondence between stress and structure in Mo and γ-Mo2N films prepared by reactive sputtering.
Changes in gate threshold voltage (VT), carrier mobility (μ), and low-frequency-noise characteristics have been investigated for n-channel MOSFET's, into whose channel region 11B+, 27Al+, 28Si+ and 31P+ ions were implanted through their gate oxide film. In case of Si implantation, a slight decrease in μ still remained after 15min. anneal at 950°C, while no significant change was observed in VT or in noise characteristics. Introduction of acceptor ions resulted in a substantial decrease in μ, and an increase in low-frequency noise level. The shift in VT was found to be proportional to implantation dose up to 1012 cm-2 in case of B+ and P+ implantation. It is possible to detect the effct of radiation damages from the changes in VT of MOS-FET's. From the annealing behavior of Si+ implanted MOSFET, the activation energy of annihilation of such radiation damages was obtained to be 0.35 eV.
Molecular orientation of a nematic liquid crystal, p-methoxybenzylidene p-n-butylaniline, injected into sandwich-type cells is determined by simultaneous measurements of dielectric constant, conductivity and optical transmission and partially by conoscopic observation. Various kinds of wall-surface materials are investigated by X-ray diffraction method and electron microscope, in connection with the molecular orientation of the liquid crystal. X-ray diffraction patterns showing the strongest line of (110), and (200) or (211) of SnO2 rutile structure, of which the latter two consist of Sn atom, correspond to the walls which orientate the long axes of the molecules parallel and normal to the walls, respectively. Molecular orientations to the Sn, Al and Au walls are similar to (200) or (211) planes of SnO2. Influence of temperature, impurities and aging on molecular alignment are also investigated.