Cross sections for photo-reactions of Al²⁷, C¹² and Cu were measured by the activation method in the γ-ray energy range from 150 MeV to 720 MeV. The integrated cross sections for the reactions Al²⁷(γ, π⁺) Mg²⁷, Al²⁷→Na²⁴, Al²⁷→F¹⁸, and C¹²→C¹¹ in the energy region between 200 MeV and 400 MeV were 2.2×10⁻²⁶ cm²·MeV, 6.2×10⁻²⁶ cm²·MeV, 2.4×10⁻²⁶ cm²·MeV, and 2.0×10⁻²⁵ cm²·MeV, respectively. These values seem to be plausible ones from the point of view of the pion photo-production, the non-mesonic dipole absorption of photons, and the reabsorption of the pion in the nucleus. The excitation curves for the reactions Al²⁷ (γ, π⁺) Mg²⁷ and Al²⁷→Na²⁴ show that the (3/2, 3/2) resonance state of a nucleon has an appreciable effect on these reactions, however, the resonances appear to be broadened probably due to the momentum distributions of nucleons in the nucleus.

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A calculation of the ultrasonic attenuation due to impurity scattering in a degenerate interacting electron gas is carried out. Contributions from diagrams of all possible combinations of the ladder interaction and exchange self-energy part are included. The result is essentially the same as those in the previous work, in which the Coulomb correlation was neglected.

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Absorption spectra of a combination mode ν₁+ν₄ of NaNO₃ single crystal are studied over the temperature range between 26°C and 29°C with a polarized infrared radiation. It is found that as temperature rises halfband width markedly broadens as the temperature approaches the transition point of 275°C. The band shape in the high temperature phase is in good agreement with the relative intensity distribution curve calculated on an assumption that the NO₃ ions are rotating freely around the threefold axis. The broadening of the band at any temperature can be explained satisfactorily if the two contours of the band observed at 26°C and 275°C, respectively, are superposed with an appropriate intensity ratio.

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The magnetic susceptibility and antiferromagnetic resonance of CoO are studied on the basis of Kanamori’s theory, in which the residual orbital angular momentum plays an important role in the magnetic properties of CoO. The parallel susceptibility does not vanish at 0°K due to the unquenched orbital angular momentum. The calculated parallel, perpendicular, and powder susceptibilities are in good agreement with measured values. The antiferromagnetic resonance modes and frequencies are calculated by the method of using fictitious magnetic fields. In the absence of an external field there are four modes, which are pair-wise degenerate. The obtained frequencies at 0°K are 5.76×10¹² sec⁻¹ and 16.61×10¹² sec⁻¹, which correspond to far-infrared wavelengths of 52.0 microns and 18.1 microns, respectively.

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Nuclear magnetic resonance studies on Mn⁵⁵ in α- and β-Mn metals have been made by both the steady and the pulse methods.
Nuclear spin-lattice relaxation time T₁ and spin-spin relaxation time T₂ were measured by the pulse method in the temperature range of 1.5°K to 77°K. The measured value of T₁T of β-Mn keeps a constant value of 7 m sec °K through the temperature range measured. Using both the T₁T value and the Knight shift, the origin of the effective magnetic field acting on a nucleus in a Mn metal was concerned. T₂ of 0.1 m sec. was observed to be temperature independent.
Several nuclear spin-lattice relaxation mechanisms together with the origin of the effective magnetic field in the Mn metal are discussed. T₁ due to the dipole, quadrupole, and orbital interactions is calculated using free electron approximation in which the electronic wave function includes partly p- or d-character. It is shown that the orbital interaction is more effective than those due to the dipole or quadrupole interaction.
Mn⁵⁵ nuclear magnetic resonance in an antiferromagnetic α-Mn metal was observed by the pulse method in zero external magnetic field and at temperatures of 1.5°K to 4.2°K.

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The self-magnetoresistance of Bi has been calculated for the pre-pinch regime, based on the energy band model proposed by Abeles and Meiboom. The inward-driven electron-hole flow contributes to departures from Ohm’s law in the following ways: a) particle flow due to the Lorentz force of the self-magnetic field gives a pure self-magnetoresistance effect, which decreases the conductivity, b) if the life time of the electron-hole Pairs is not too short, this particle flow distorts the carrier density distribution, creating a diffusion force which opposes the Lorentz force. This effect partially compensates the pure self-magnetoresistance effect, c) if the surface recombination velocity is not zero, the particle flow increases the carrier density, so that the conductivity is increased.

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An analysis for the infrared absorption by free carriers in n-type InAs is carried out on the basis of the previous theory developed for n-type InSb, in order to investigate the scattering mechanism. The magnitude of the deformation potential constant E₁ is found to be 10 eV, and it is found that the contribution from acoustical phonons is not important for all samples of Dixon. The impurity concentration is found to be N_imp=11 N_e for the sample A of the smallest carrier concentration: N_e=2.8×10¹⁶cm⁻³, and to be N_imp=N_e for the other samples. Optical phonons make the most important contribution for samples of relatively low carrier concentrations except the sample A, in which the contribution from impurities is comparable to the one from optical phonons.
The presence of an unknown scatterer in the sample A is suggested and a discussion for this is given. A discussion on the screened Coulomb potential used in the calculation of the impurity scattering also is given.

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The dielectric constant of GSN measured along the ferroelectric b-axis obeys the Curie-Weiss law with the Curie-Weiss constant of 446°C. Dielectric behavior in the vicinity of the Curie point is well explained by the phenomenological theory. The coefficient ξ of the P⁴ term \left(\frac14ξP⁴\ ight) in the Taylor series expansion of the elastic Gibbs function has been determined as ξ=6.4×10⁻⁷ cgs esu by use of the temperature dependence of P_s². The lattice deformations associated with the spontaneous polarization suggest a strong interaction between the polarization and the crystal lattice in GSN.

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The relaxation frequency for electron-electron scattering of an electron having energy more than a few k_BT above the Fermi level in a metal is calculated in the Born approximation by assuming a phenomenological Yukawa potential. The same method is then used to calculate the relaxation frequency of a hole having energy more than a few k_BT below the Fermi level in a metal and to calculate the relaxation frequency of an electron in a semiconductor having spherical energy bands. For electrons in a metal our result is compared with the result obtained in a dielectric constant calculation.

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The tables of numerical values of Lorentz field are given for the simple cubic lattice. Ewald’s method suitable for the machine calculation was used.

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A calculation of the electrical conductivity of alkali metals is carried out within the limit of the one-electron approximation. The band structure obtained by Ham and the phonon spectrum determined by experiments are taken into account in the calculation. The absolute values of the conductivity of Li, Na and K at room temperature are evaluated and compared with experiments. The agreement between the theory and the experiment is reasonably good. The temperature dependence of their conductivity is evaluated. In the case of potassium the agreement between the theory and the experiment is quite good down to the very low temperature. In the other two cases, the agreement is reasonably good down to 80°K, but becomes worse at low temperatures. The pressure dependence of their conductivity is also evaluated. The theoretical values dlnρ⁄dln V of Li, Na and K are −1.7, 4.4 and 5.1, while the observed values are −0.7, 4.4 and 5.5, respectively.

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The thermal dilatation of VO₂ has been measured on ceramic samples from room temperature to 95°C, in connection with Mott’s consideration which interpretes the non-metal to metal transition observed in some transition metal oxides as an effect of contraction of lattice spacings. A discontinuous volume expansion was unexpectedly observed at 65°C with increasing temperature. The magnetic susceptibility has also been measured in the vicinity of the transition point. Below the transition point it has a temperature indenpendent value and at the transition point it makes a stepwise increase, but no singular peak was observed there. A measurement of the temperature dependence of the specific heat was carried out by an adiabatic type calorimeter. A distinct anomaly was observed near the transition point and the transition heat was estimated as about 750 cal/mol. These data suggest that the transition would be of the fist kind.

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Based upon thermodynamical theory of a phase transition of the second kind, the effect of pressure on the Curie temperature in the Invar-type iron-platinum alloys with the order-disorder transition has been estimated from the measurements of the temperature dependences of magnetization and magnetostriction. Onset of atomic ordering of the alloys tends to decrease the effect of pressure on the Curie temperature. But, contrary to this tendency, the change of the Curie temperature with pressure in quenched alloys is smaller than the expected value.
The discontinuity ΔC_p in the specific heat at the Curie temperature has also been estimated by Landau’s formula. The quantity ΔC_p of the disordered state is larger than that of the ordered one. The convenient general expression of the discontinuity in thermal expansion coefficient at the Curie temperature is obtained and on the basis of this expression, it is pointed out that the relation Δθ⁄ΔP=−C_θ⁄A_θ′, which was derived by Belov, is equivalent to Ehrenfest relation.

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Temporary bleaching of color centers in additively colored KBr and KCl crystals are investigated. The first and the second absorption bands of M center are bleached by F-light or M-light irradiation at 90°K. Accompanying with the bleaching of the M band, two absorption bands grow at 555 mμ and 780 mμ in KBr and at 505 mμ and 690 mμ in KCl. These bands as well as the bleached M bands show dichroism when the original M band is dichroic. The oscillator strengths of these bands are determined with respect to the M band, and discussions on the nature of the bands are made.

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The atomic coordinates of one previously unknown water oxygen in potassium ferrocyanide trihydrate are determined by X-ray structure analysis in the paraelectric phase at room temperature. In K₄Fe(CN)₆·3H₂O and its isomorphous K₄Ru(CN)₆·3H₂O proton magnetic resonance patterns start to narrow at about −140°C, and definite change in both spectra occurs in the same temperature region around −40°C, about twenty degrees below the respective Curie points. Angular dependence of peak separations has been measured at liquid nitrogen temperature where all water molecules are effectively rigid. Direction angles of three proton-proton vectors with respect to the crystallographic a, b and c axes are, respectively, α₀=134°, β₀=49°, γ₀=73°; α₀=90°, β₀=90°, γ₀=0° and α₀=0°, β₀=90°, γ₀=90°. A possible molecular mechanism for the ferroelectric origin is discussed.

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Antiparallel domain configurations in c-plate crystal are observed in {003} x-ray reflection micrographs by the intensity contrast caused by anomalous scattering of the incident CrKα radiation by Ba and Ti atoms.
The micrographs are taken with the scanning method of Lang applied to the reflection case.
Measured ratio between |F(00\bar3)|² and |F(003)|² by a single-crystal-diffractometer amounts to 1.16. It is shown that with this reflection the antiparallel domains can be clearly discriminated in the x-ray reflection images with strong intensity contrast, and that the domain reversal process can be followed non-destructively.

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Nonlinear stationary electron plasma waves are investigated in one-dimensional case. Full account is taken of the effects of both kinds of electrons which are trapped and untrapped in potential troughs. A condition for the existence of plasma waves which is periodic in space is obtained in the case that the amplitudes are sufficiently small. The waves are classified into harmonic and unharmonic waves. It is shown that while the electron distribution function for the former is continuous, that for the latter has a discontinuity. A dispersion relation for the harmonic waves which was obtained by Van Kampen is rederived.

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Ultrasonic velocities in and densities of binary liquid mixtures of benzene, carbon tetrachloride, carbon disulphide, P-xylene, m-xylene, o-xylene toluene, dioxan and tetralin with cyclohexane as common component have been determined at room temperature, The nature of the excess compressibility and excess volume of these mixtures has been discussed in the light of the recently developed molecular theories of solutions. The agreement between the calculated and experimental excess functions has been found to be good in all cases excepting the system cyclohexane-toluene. The nature of the velocity v_s mole fraction curves has been explained by extending the concept of available volume and intermolecular free length to liquid mixtures.

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This paper describes effects of close collisions on ion oscillations in a fully ionized plasma. The damping rate due to the ion-ion collisions is derived from the Boltzmann-Vlasov equation which includes the collision terms used by Bhatnagar et al. (cf. Phys. Rev. 94 (1954) 511). The so-called “two-stream instability” in a plasma is considered in some detail taking into account the effects of the collisions. As the collision frequencies become large compared with the frequencies of oscillations, the results tend to those of the two-fluid model and the ion oscillations are stable so far as the relative drift velocity between electrons and ions is not larger than the thermal velocities of these particles.

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Fig. 1. (a) is in correct and should be corrected as shown in the figure of the errata.

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