Electron microscopic observation was carried out on fission fragment-irradiated molybdenite crystals. Tracks of fission fragments in the crystals were observed as continuous straight lines and linear arrays of spots and rings. From the change of their image contrasts in the tilting experiment and the disturbance in the moiré patterns around the tracks, it was found that the track consists of a narrow non-uniform cylindrical region associated by some dotted blister-like swellings. The origin of such blister-like regions may be interpreted by either of the non-uniform solidification in the temperature spiked region along the path of fission fragment or more probably the displacement spike effect by the knockons with energies higher than about 500 eV. Bent and forked tracks resulting from nuclear collisions between fission fragments passing through the lattice and atoms on the lattice sites were observed and analysed. Interaction between dislocation lines and the tracks was observed, indicating that strong stress fields around the tracks cause the slip motion of the dislocations by elastic interaction.

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The variation of the cross section for P³¹ (p, γ₀), (p, γ₁) S³² reactions with proton energy from 7.8 to 14.2 Mev, were measured using 4″φ×4″ Nal (T1) crystal spectrometers. The gamma rays corresponding to the transitions to the ground and first excited state of S³² showed giant resonance with complicated structures. (p, γ₀) falls off at about 13 Mev with full width of about 7 Mev if Harwell’s result is combined. (p, γ₁) does not show indications of fall-off at least up to about 14 Mev. Some results on Cu⁶⁵ (p, γ) are also mentioned.

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Theoretical consideration of the anisotropy energy of CrO₂ is given. Considering the effect of the crystalline electric field and the dipole interaction, the second order and fourth order terms of the anisotropy energy are calculated. Recent experimental results are interpreted, assuming that the effect of the crystalline electric field and the dipole interaction almost completely cancel each other.

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The time-dependent plastic properties in wet-hydrogen-treated iron were observed at −78°C. The stress-strain curves at various strain rates showed gradual yield drops at yield point and no inhomogeneous deformation i. e. Lüders band. The creep curves showed an exponential rise of plastic strain at an early period of creep. Observed results were analysed by the strain rate equation, \dotε=bnv. The magnitude m in the dislocation velocity-stress relation, v^∞σ^m, is obtained to be about 10 from the stress sensitivity of strain rate at a constant strain. It is concluded that the upper yield stresses in the present experiment are not closely relatated to the stress required to unpin dislocations.

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A formulation is presented which describes the inelastic scattering of electrons by a crystal with a definite momentum transfer and a small energy loss. The Bragg reflection of both the elastic and inelastic waves is treated in the frame of the dynamical theory. This formulation is especially suitable for the discussion of the inelastic scattering in the plasmon-excitation process, where the Bragg condition for the inelastic wave is not so much altered from that for the elastic one because of the small change of momentum in this process. A numerical example for the intensity of the inelastic waves is demonstrated to describe the equi-thickness interference fringes formed by plasma loss electrons.

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The possibility of cooling by an optical process of ruby is pointed out. When Cr³⁺ ions in ruby are optically pumped by photons with a given energy and emit photons with higher energies, the lattice energy can be extracted as light, so that a cooling effect appears. If some possible heating effects did not overcome this cooling effect, the temperature would be actually reduced. Cooling rates and cooling capacities are given. If we could have light input powers 10⁻¹ Watt or 10⁻² Watt for optical pumping, it might be possible to cool from 80°K or 20°K to temperatures below 1°K, respectively. Technical problems and possible heating effects are discussed.

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A statistical theory of antiferromagnetism, which is an extension of Nakamura’s and Kasteleijn and Kranendonk’s theory, is developed. Our theory reasonably well explains the unusual behaviors of paramagnetic susceptibilities of CuF₂·2H₂O and CuCl₂·2H₂O. The theory is compared with experiments, and the following information is obtained. In the case of CuF₂·2H₂O, the ferromagnetic exchange coupling constant is smaller than about 1/3 of the antiferromagnetic exchange coupling constant. The ratio of these two exchange coupling constants in CuCl₂·2H₂O is about 0.55, which differs from 0.3 proposed by Oguchi and 0.165 by Marshall.

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The rate of the nuclear spin-lattice relaxation due to the hyperfine interaction is shown to be enhanced by a repulsive electron-electron interaction. The relaxation time is expressed in terms of the wavelength and frequency dependent magnetic susceptibilities of the conduction electrons. The magnetic susceptibilities are calculated taking account of the electron-electron interaction of the δ-function type with a random phase approximation. The Korringa relation between the frequency shift and the relaxation time is shown to be altered by the electron-electron interaction. The theory applies also to the electron spin relaxation of localized magnetic atoms in certain alloys.

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Spatial variations of the spin axes and strain components in twin walls (T-walls) in antiferromagnetic NiO are studied theoretically. Exchange energy, dipolar energy and elastic energy determine these variations. An exact solution is obtained in the case of 90° wall. The wall width in this case is found to be about 40 Å and the self-energy to be 3.5 erg/cm². Approximate solutions are obtained in the case of 180° wall and 60° wall. Possible orientations of T-walls as well as those of S-walls which separate different magnetic domains in a twin-free domain are discussed on the basis of the compatibility conditions of elasticity theory.

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Fluorescence and phosphorescence have been observed in a naphthalenedoped crystal of durene. Measured fluorescence spectra at various conditions show a transfer of excitation energy from durene to naphthalene molecules and a build-up of a new green band by irradiation of shorter ultra-violet light. Phosphorescence spectra and decays show that phosphorescence is due to a transition from a triplet state to a ground state in a naphthalene molecule. Two decay times have been observed, a larger one belonging to an ordinary triplet state and a smaller one belonging to a triplet state coupled with a newly introduced center emitting a green band. An energy level scheme in the crystal is presumed.

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The Lampert-Rose one-dimensional theory of double injection is extended to two dimensions so as to facilitate comparison with experiment. The two-dimensional theory is carried out for cylindrical and infinite-slab cross-sections. Making the assumption that the transverse current flow is purely diffusive, the earlier, one-dimensional result of Lampert and Rose is recovered, namely J=(9⁄8)eμ_eμ_pτ_eff(n_T-p_T)V²⁄L³, where their pure bulk lifetime τ is replaced by an effective lifetime τ_eff which takes into account the effect of surface, as well as bulk, lifetime. Explicit formulae are presented for τ_eff The results for the infinite slab are compared to the earlier results of Shockley for the low-injection level, purely diffusive flow of injected carriers.

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The magnetic susceptibility of single crystals of Cu(HCO₂)₂·4H₂O was measured at temperatures between 1.4°K and 80°K by a. c. bridge and magnetic balance method. This salt is an example of the magnetic two dimensional lattice. The interaction between Cu²⁺ ions is mainly the superexchange interaction through a formate ion in the same layer. From the Weiss constant of about −150°K, it is concluded that strength of superexchange interaction through a formate molecule, –(O–CH–O)–, has the same order as that through one diamagnetic atomic ion such as –(Cl)–. The existence of a broad maximum of the susceptibility at about 60°K implies the appearence of short range order in the two dimensional lattice. The antiferromagnetic transition accompanied by parasitic ferromagnetism was found at 17.0°K±0.2°K. The weak ferromagnetic moment in L₁L₂ plane was about 150 c. g. s. e. m. u. at 0°K. Along L₃ axis, no ferromagnetic moment was found. The susceptibility of isomorphous Cu(HCO₂)₂·2H₂0·2(NH₂)₂CO was similar to that of Cu(HCO₂)₂·4H₂O.

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Thermal denaturation and renaturation processes of DNA-type molecules are studied, using two models of DNA-type double-chain which were previously treated by Zimm and Hill. In these two models, the difference between the bond energies of the two kinds of base pairs, guanine-cytosine and adenine-thymine, is taken into account, assuming the random sequences of four bases in the double-chain. Then it can be shown that the two models have essentially different characters for the dependence of transition temperature upon the guanine+cytosine content. The first model gives an almost linear relationship between the transition temperature and guanine+cytosine content, but the second gives an almost quadratic relationship. These results are discussed, using the experimental data given by Marmur and Doty, and Eigner.

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In connection with studies for developing a microwave discharge chamber which detects tracks of charged particles, a number of important properties of a pulsed microwave discharge have been investigated. A pulsed microwave field of variable pulse widths, τ_p=0.1∼2 μ sec, has been applied to a mixture of neon and argon at a total pressure of 100 mm Hg, but with various mixture ratio. The results are; a) the breakdown field strengths are approximately by one order of magnitude higher than those in continuous RF discharges and are less sensitive to the relative concentration of argon in neon, r, for smaller τ_p, b) the breakdown field strength decreases with increasing r, reaches a minimum and increases again with a further increase of r, and c) the optimum value of r for the minimum breakdown field strength increases with decreasing τ_p. These properties can be explained in teams of the direct ionization whose relative contribution becomes predominant as E⁄p increases and/or τ_p decreases. The so-calld Penning effect is found to be important only for a low value of E⁄p. The observed formative time lags and the time variation of particular line intensities are also in essential agreement with our theoretical analysis.

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The instability of positive column is investigated theoretically, under the assumption that the densities of electrons and ions are perturbed independently. The electric field induced by these perturbations is derived exactly by solving Poisson’s equation. For helical perturbations, the existence of a finite potential at the wall is found. A relation between the critical magnetic field above which the perturbation is unstable and the corresponding electric field is obtained. It depends upon the discharge current; and this dependence is in good agreement with Hoh and Lehnert’s experiments.

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It has been shown that when a dilatant power law fluid flows past a flat plate with uniform suction, the velocity component parallel to the plate is unaffected beyond a certain height above the plate. A similar phenomenon occurs for the flow of such fluids between two plates when there is uniform suction at one plate and uniform injection at the other. If the height between the two plates exceeds a certain value, the fluid in the neighbourhood of the moving plate with injection moves as a rigid blug along with that plate. Solutions have also been obtained for pseudo-plastic power-law fluids.

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The ultrasonic absorption and velocity in solutions of formates, acetates and propionates of sodium and calcium with regard to their temperature and concentration variation have been studied over the frequency range 4–26 Mc/s to investigate the associated relaxation processes. It is found that in the case of calcium salts the contribution of chemical relaxation to absorption is comparable to that dud to other causes such as viscosity whereas in the case of sodium salts most of the absorption is due to causes other than relaxation.

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