[en] A survey of principal research on the backscattering of gamma rays is described. This is a macroscopic phenomena composing many photons scattered backward from a surface of material. After a historical survey as an introduction, principal theme of research is described; nomenclature of albedo, Monte Carlo calculation, measurement of albedos, semi-empirical formula of the differential albedo, exposure dose rate distribution outside a scatterer, distribution of scattered gamma rays on the surface. 106 references

[en] We study the K⁺p→π⁺K⁺n reaction with some kinematics suited to the production of the Θ⁺ resonance recently observed. We show that, independently of the quantum numbers of the Θ⁺, a resonance signal is always observed in the K⁺ forward direction. In addition, we also show how a combined consideration of the strength at the peak, and the angular dependence of polarization observables can help determine the Θ⁺ quantum numbers using the present reaction

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[en] Positronium forms in various insulating solids. Observation of the energy of the positronium emitted from the surface carries information on the relevant energies inside the material. Analysis of the positronium peak in ACAR spectra gives information on the Bloch modulation of the Ps wave function, the Ps-phonon interactions, the size and anisotropy of the Ps localization site, Ps self-trapping, etc. Magnetic quenching is applied to investigate the positronium pickoff annihilation rate, contact density of the Ps wave function, and positron spin polarization. (orig.)

[en] The photo-induced K* vector meson production is investigated for the study of the Λ(1405) resonance. This reaction is particularly suited to the isolation of the second pole in the Λ(1405) region which couples dominantly to the K-bar N channel. We obtain the mass distribution of the Λ(1405) which peaks at 1420 MeV, and differs from the nominal one. Combined with several other reactions, like the π^-p→K⁰πΣ which favours the first pole, this detailed study will reveal a novel structure of the Λ(1405) state

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[en] The evaluation of the dose level in the proposed R-tokamak experiment is the essential problem. The nuclear radiation is estimated by using the 1-D P₅S₈ ANISN code, to which cylindrical and spherical models are applied. Attention is paid to the induced activity of stainless steel together with Al-alloys as the structural materials. Assuming that 10³ D-T shots are performed, the total neutron fluence becomes 1.6 x 10¹⁶ n/cm² in the R-tokamak. The doses just outside the device-shielding (igloo in TFTR) and on the inner surface of the building wall are 2.6 x 10³ rem/shot and 1.0 x 10² rem/shot, respectively. The induced activity of structural materials was calculated with THIDA code developed in JAERI. In the case of stainless steel, the dose rate is 4.5 mrem/h after 1 week from the spot, and decreases to 2.5 mrem/h after 3 months. As for the case of Al-alloy, the dose rate is 10 mrem/h after 1 week, but it decreases to 0.1 mrem/h after 2 weeks. The dose rate due to the additional elements in the Al-alloy was estimated. The activation of the air was calculated with 1-D ANISN code. The concentration of Ar-41 is the most important one, and is 220 pCi/cc/shot inside the device-shielding. It may be possible to enter the test cell after the cooling time of 1 day. The activation of cooling water was estimated. The dose in the environment due to the skyshine was calculated. The ceiling thickness of about 120 cm is necessary. The dose rate in the D-D discharge was also estimated. (Kato, T.)

[en] It is investigated whether a new method to analyze the short lifetime component by using the positron age-momentum correlation technique (AMOC) can be applied to determine the lifetime of para-positronium in some insulation materials. The results indicate that the method is not applicable to the case.