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[en] Although specialists in the field of electric discharges have known about the streamer phenomenon for many years, the discovery of the SQS phenomenon was made by detector physicists, many of whom were not so familiar with the underlying theory of electrical discharges. Consequently, many specialists in the field of electric discharges are still not fully aware of the existence and the potential importance of the SQS mode. This may be one of the principal reasons why the mechanism responsible for the SQS mode is still not fully understood. If the potential importance of the SQS phenomenon were to be emphasized to specialists in the field of electrical discharges, they would surely have a deep interest in it, and from this interest many useful insights would certainly follow. What is needed is an understanding of the underlying physical mechanism responsible for the SQS phenomenon ahd its dependence on the independent variables such as voltage, the identity of gases, their concentrations, etc. Accelerator physicists have shown a great interest in detectors based on the SQS phenomenon. Such detectors can have extensive applications outside the fields of high energy and nuclear physics. By selecting the gases and their pressures advantageously it should be possible to develop SQS detectors that are equal to or better than GM counters. (N.K.)

[en] Japan will take part in the LML-1 (International Microgravity Laboratory 1) program that is scheduled to be carried out with space shuttles to be launched in 1991. The program will be followed by the LS-J (Space Laboratory-Japan) and IML-2 programs. A reliable dosimetry system is currently required to be established to evaluate the radiations in space. The present article reviews major features of different types of space radiations and requirements of dosimeters for these radiations. The radiations in the space environment consist of: 1) electrons and protons that have been trapped by the terrestrial magnetism, 2) corpuscular, gamma-and X-rays released from the sun, and 3) galactic cosmic rays (corpuscular, gamma-and X-rays). The effects of the trapped radiations will be low if a spacecraft can get through the zone of such radiations in a short period of time. The effects of galactic cosmic rays are much smaller than those of the trapped radiations. A solar flare can give significant contributions to the total radiations received by a spacecraft. An extremely large flare can release a fatal amount of radiations to the crew of a spacecraft. Prediction of such a large flare is of great important for a long trip through the space. Significant improvements should be made on existing dosimeters. (Nogami, K.)

[en] The calculation of the production rates of nuclides induced by cosmic-rays in the cosmic dusts has been done considering the falling time of dust particle. The results show that the production rate of radioactive nuclides with half-life shorter than 10⁵ years due to the solar cosmic-rays is almost equal to that estimated under the assumption of the radioactive equilibrium at the earth orbit as often done so far, but for radioactive nuclides with half-life longer than 1x10⁶ years the dust dynamic should be considered in the calculation. Furthermore, the calculation shows that, for the nuclide whose excitation function has no peak in the low energy region such as ¹⁰Be, the contribution of the galactic cosmic rays in the isotope production becomes very important, contrary to the ordinary expectation. (auth.)

[en] Recently, plans have been developed for the construction of bases on the moon and launch of manned spacecraft to Mars. In the present report, the level of radiations in space, possible exposure of astronauts to radiations, appropriate levels of permissible exposure to such radiations, and available techniques to measure the dose equivalent are discussed in relation to long stays of astronauts in space outside the magnetosphere. Specifically, the report first outlines major features of radiations in the space environment focusing on electron and proton beams caught by the terrestrial magnitism, radiations released by the sun and galactic cosmic rays, and then presents estimations of possible exposure dose in space focusing on the contributions of electron and proton beams caught by the terrestrial magnetism, radiations released by the sun and galactic cosmic rays. The report also addresses guidelines for protection from radiations in space, techniques for measuring the intensity of radiations in space. It is pointed out that more studies should be made to permit accurate measurement of radiation doses in a mixed field containing high-energy heavy particles. (N.K.)

[en] The disposal of the radioactive wastes from nuclear power generation through nuclear transmutation is significant, and deserves attention, since the treatment can be done in time by the society benefiting from it. As the feasible means, there are the following treatments, (1) in nuclear fission reactors, (2) in high energy proton accelerators, and (3) in nuclear fusion reactors. The results of feasibility survey on the respective methods are described in view of the period required for the decay to natural level of the radioactive wastes from nuclear reactors. The transmutation processing is not so promising in actuality, as it has been originally anticipated. However, the high-energy accelerators with 10¹⁷n/cm².sec neutron flux density may be useful for the purpose. (Mori, K.)

[en] The characteristics of radiation detectors for heavy ions generally present more complex aspects as compared with those for electron beam and γ-ray. There is the ''Katz theory'' applying the target theory in radiobiology phenomenologically to radiation detectors. Here, first, the Katz theory for radiation detectors is explained, then its applications to nuclear plates, solid state track detectors, scintillation detectors and thermoluminescence dosimeters are described, respectively. The theory is used for the calibration of the nuclear charge of heavy ions in nuclear plates and recently is used to simulate the flight tracks of heavy ions or magnetic monopoles. In solid state track detectors, the threshold value of the energy given along the tracks of heavy ions is inherent to a detector, and the Katz theory is applicable as the measure of the threshold. The theory seems to be superior to the other methods. However, it has disadvantages that the calculation is not simple and is difficult for wide objects. In scintillation detectors, the scintillation efficiency is not a single function of dE/dx, but depends on the kinds of heavy ions, which Katz succeeded to describe quantitatively with his theory. Such result has also been produced that the dependence of thermoluminescence dosimeters such as LiF on LET by Katz theory agreed fairly well with experiments. (Wakatsuki, Y.)

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[en] The limit of energy resolution in various radiation detectors is reviewed from the theoretical view-point. Fano-factors in gaseous, liquid and solid detector media for ionization and for scintillation are discussed and the limit of energy resolution in micro-calorimeters operated at low temperature is also discussed. (author)