Method of measuring linear polarization of bremsstrahlung at intermediate energies is discussed. The polarization is determined from the angular distribution of electron positron pairs produced in an amorphous converter. The vertical distribution of electrons is detected by a wire spark chamber or a counter hodoscope and positrons by a large counter. The cross section is obtained analytically. The maximum asymmetry ratio of the cross section is 11∼13% for photons with the energies higher than ∼100 MeV.

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The decay of ¹³⁸Cs to levels in ¹³⁸Ba has been studied with Ge(Li) detectors and Ge(Li)–NaI(Tl) coincidence spectrometer. On the basis of the singles and coincidence measurements, 33 gamma-ray transitions were observed. Thirty-one transitions except for the 773 and 1555 keV gamma rays are place in a level scheme of ¹³⁸Ba consisting of the levels at 1436.0, 1898.5, 2217.6, 2306.8, 2442.7, 2445.1, 2582.8, 2639.8, 2681.8, 2881, 3051, 3339.7, 3368.1, 3560.5, 3643, 3858, 3922, 4166.9 and 4241.8 keV. A new level at 3368.1 keV that has not been observed by the ¹³⁸Ba(p, p′), ¹³⁷Ba(d, p) and ¹³⁷Ba(n, γ) experiments are proposed in the present work. The existence of collective 3⁻ state at 2881 keV was also confirmed from decay of ¹³⁸Cs. The results are compared with those of the previous studies.

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Deuterons from the (³He, d) reaction on N=82 nuclei ¹⁴⁰Ce and ¹⁴²Nd have been measured at an incident energy of 27.30 MeV with a broad-range magnetic spectrograph. Up to 3 MeV of excitation, levels of ¹⁴¹Pr at energies 0.0, 0.15, 1.14, 1.32 and 1.64 MeV and those of ¹⁴³Pm at 0.0, 0.28, 0.96, 1.17 and 1.40 MeV were observed. The differential cross sections for the transitions were analyzed with distorted-wave calculations. Values of the orbital angular momentum of the transferred proton and the spectroscopic factors of the transitions were obtained.

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The magnetic susceptibility of single crystal of Ni(NH₃)₂·Ni(CN)₄·2C₆H₆ has been measured in liquid hydrogen and liquid helium temperature regions. The Néel temperature was found to be 2.37°K from the experimental results of proton resonance and specific heat measurements. The uniaxial anisotropy constant and the molecular field constant which are obtained from the present research, are respectively D⁄k=3.6°K and A⁄k=4.5°K and they are the same order of magnitude. The values of perpendicular susceptibility and spin-flopping field in antiferromagnetic state are well described using the values of uniaxial anisotropy constant and exchange interaction constant obtained in the molecular field approximation. The temperature dependence of parallel susceptibility χ_⁄⁄ in antiferromagnetic state is in good agreement with the theoretical result calculated by the spin wave method, over the temperature range 0∼2.2°K. The preferred direction of sublattice magnetization is the c-axis of this crystal.

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Crystal structures and magnetic properties of Pt–Mn–Sn and Pt–Mn–Sb alloys have been investigated by means of X-ray analysis, magnetic analysis and nuclear magnetic resonance. It is found that the alloys with the stoichiometric compositions PtMnSn and PtMnSb are ferromagnetic and that the former has a structure of the CaF₂ (Cl) type while the latter an ordered structure of the MgAgAs (Cl_b) type. Pt_1.01Mn_0.99Sn_1.00 and Pt_1.01Mn_0.99Sn_1.00 alloys have lattice parameters of 6.263 and 6.201 Å at room temperature, ferromagnetic Curie temperatures of 360° and 582°K, numbers of Bohr magnetons of 3.65 and 4.14 μ_B/mol at 0°K and the internal magnetic field of 204.5 and 220.2 kOe at Mn⁵⁵ nucleus at 77°K, respectively.

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Exchange interactions between two dissimilar Cu²⁺ ions in K₂CuCl₄2H₂O and K₂CuCl₄2D₂O were investigated by means of electron paramagnetic resonance (EPR). The measurements were done in the frequency range from 9.3 to 65.8 GHz between 10° and 370°K. An amalgamated single line was observed below 200°K but the line splits into two lines near room temperatures. Considering the frequency and temperature dependence of the phenomenon, it is concluded that the exchange interaction depends strongly on temperature. The magnitude of the exchange interaction J⁄k(°K) varies from 0.3 to 0.08 between 4° and 300°K. Similar temperature dependence was obtained in K₂CuCl₄2D₂O and the exchange interaction in this compound was found to be about 0.02°K larger than of K₂CuCl₄2H₂O.

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The internal magnetic fields of Mn and Sn nuclei in Ni₂MnSn, Co₂MnSn and Ni₂MnSb were measured with the spin-echo N. M. R. method, as well as their thermo-magnetic curves. The Curie temperatures measured of Ni₂MnSn and Ni₂MnSb were different from Castellitz’s data, and a sluggish change of the magnetization in Ni₂MnSb was observed, near the Curie temperature. The NMR signals of Mn nuclei were observed in Co₂MnSn, Ni₂MnSn and Ni₂MnSb. The internal magnetic fields were 352.3, 312.7 and 285 kOe, respectively. An unexpected resonance signal appeared in Ni₂MnSb and was interpreted as originating from Mn atoms occupying non-regular sites. The resonance signals of Sn nuclei were also observed in Co₂MnSn and Ni₂MnSn. The internal magnetic fields were 153.8 and 150.4 kOe, respectively. The difference in the internal magnetic fields of the above compounds from those of Cu₂MnSn can be tentatively attributed to the difference in the conduction electron polarization by RKKY interaction.

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Magnetizations in the three main planes of a single crystal of manganese phosphide are measured at 4.2°K. Especially the b-axis magnetizations are studied in detail in the range of magnetic field up to 80 kOe at various temperatures. The screw-spin state of ferromagnetic spin state transforms to the fan state and than to the complete paralell arrangement by the external magnetic field applied along the b axis. From the results obtained, the spin structure diagram is made as a function of temperature and of magnetic field applied along the b axis.

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A study on ²³Na nucleus in sodium nitrite, NaNO₂, in the vicinity of phase transition temperatures was made using nuclear magnetic resonance. Simultaneous measurements of the spectrum and the dielectric constant ε_b made the one to one correspondence between them clear. The main results were as follows: A discontinuous jump of an electric field gradient tensor and thermal hysteresis were found at the transition temperature T_t. The curves of quadrupole splitting versus temperature show a small kink at the transition temperature T_n. Only one pair of satellite lines was observed in the sinusoidal antiferroelectric phase. The asymmetry parameter of the electric field gradient tensor, η, becomes zero at 0.3°∼0.4° below T_t in the cooling runs.

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A general expression of the dynamical transverse spin susceptibility for ferromagnetic dilute alloys of transition metals is obtained in the ladder approximation by using the Wolff-Clogston model for dilute alloys and by taking into account exchange interactions among electrons in the host metal. The dispersion relation of spin waves is calculated from the pole of the dynamical transverse spin susceptibility by making use of the one-particle Green’s function obtained in the Hartree-Fock approximation and by assuming that both impurity potential and the difference between intra-atomic Coulomb integrals in the impurity and host atoms are small. The values of exchange stiffness constants are estimated and compared with experimental data for dilute nickel alloys with iron, copper and palladium. The possibility of the appearance of a local spin wave mode is discussed.

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The lattice dynamics of metallic silver has been studied by assuming silver ions embedded in a uniform sea of electrons. The entire interaction has been divided into three, coulombian, repulsive and electron-ion part. The coulombian coupling coefficients have been taken directly from the work of Kellermann. The repulsive and the electron-ion part has been calculated in the manner given by Dayal and Srivastava, and Sharma and Joshi. The effect of the volume forces has been included in the manner of Dayal and Tripathi. The first Brillouin zone has been divided into 10×10×10 points and the secular determinant has been solved for the 48 non-equivalent points. The phonon dispersion curves in the [100] and [111] directions and the theoretical and experimented Debye temperature Θ versus T curves have been plotted. The agreement between the theory and the experiment for the latter is found to be reasonable.

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This communication presents a new approach to the lattice dynamics of hexagonal metals in which the electron ion contribution has been introduced in a manner outlined recently by the authors. Three metals with different axial (c⁄a) ratios have been considered: they are beryllium (1.568), magnesium (1.624) and thallium (1.597). The ion-ion interaction has been restricted up to the fifth neighbours for beryllium and upto the fourth neighbours for magnesium and thallium. The force constants have been related with the elastic constants in the long wave length limit. The dispersion curves have been drawn for [0001] and [01\bar10] directions for all the three metals and are found to be in satisfactory agreement with the results of neutron scattering on beryllium and magnesium. No comparison has been made for thallium for lack of experimental data on it.

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De Launay type angular force model has been applied to sodium to study the dispersion relations in the three symmetry directions. Electron-ion interaction has also been taken into account. The theoretical results are compared with the experimental ones obtained from inelastic neutron scattering and an excellent agreement has been obtained. The Cauchy discrepancy is attributed to the presence of both types of non-central interactions.

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Alfven wave transmission through bismuth single crystals is measured using 50 Gc microwave interferometer under pulsed magnetic field up to 200 kG at liquid helium temperatures. It is found that the mass densities change remarkably with magnetic field for all cases studied. These changes are ascribed to the quantum variation of Fermi energy at high magnetic field. The shifts of Fermi energy are determined as a function of magnetic field assuming the nonparabolic band for holes. From the analysis based on the Baraff’s theory, it is found that the lowest Landau levels of light electrons go down linearly with magnetic field instead of the parabolic change expected from the modified two band model.
It is also found that the lattice dielectric constant has an anisotropy. If ε_⊥\doteqdot100 is adopted according to Boyle and Brailsford, we obtain ε_⁄⁄\doteqdot60 in the present experiments, where ε_⁄⁄ and ε_⊥ are the dielectric constants for waves polarized along and perpendicular to the trigonal axis, respectively.

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An elastic tunneling from a metal to a semimetal through an insulating layer is considered. Tunnel current and conductance have been calculated for the case when an energy band of the semimetal along the tunnel direction is non-parabolic, using the WKB approximation. It has been shown that tunnel conductance rises linearly from a voltage corresponding to a band edge and has a peak or a bump at a saddle point. Experimentally, conductance voltage characteristics of Al–Al₂O₃–Bi junctions have been measured at 4.2, 77 and 300°K. Five peaks or bumps are observed at −0.77, −0.16, +0.16, +0.72 and +1.6 volts in the range of −1.2∼+2.2 volts. Energy band models of bismuth are proposed in order to explain an experimental conductance curve and compared with theoretical calculations by Golin and Mase. Current decrease with temperature rise has been observed and is attributed to the temperature dependence of dielectric constant of aluminum oxide.

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The superconducting transition temperatures of copper sulfide CuS are measured as a function of hydrostatic pressure up to about 9 katm by an ice bomb technique. The superconducting transition is detected with the ac Hartshorn mutual inductance bridge. In contrast to ordinary superconductors the curve of the shift of the transition temperature with increasing pressure decreases nonlinearly with downward curvature over the whole range of applied perssures and its slope changes discontinuously at about 3.5 katm. The maximum peak of the imaginary part of the ac susceptibility vanishes under pressures above about 1.6 katm.
It is discussed that the observed unusual behaviour of the transition temperature is probably attributed to a change of the Fermi surface of the type proposed by Lifshitz.

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Domain sizes of long period superlattices in alloys are calculated by minimizing the ordering energy which mainly originates from the energy of conduction electrons. The domain size M thus obtained has a strong tendency to be fixed at integral numbers. This tendency explains the experimental results that the periods are fixed at M=2 in A₃B-type alloys, such as Au–Cd, Au–Zn, and Pd–Mn, independently of their electron-atom ratios. The anomalous dependence of M on the electron-atom ratio in the Ag–Mg alloy system is also explained.

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The new measurement of the specific heat of bcc 5d transition metal alloys of Ta–Re series containing up to 40 atomic % of Re has been made and their superconducting behaviours of the alloys including up to 20 atomic % of Re have been studied. By making use of McMillan’s theoretical treatment, the electron-phonon coupling constant and bare electronic density of states were deduced. The electron-phonon coupling constant, as a function of the number of electrons per atom, bahaves in the same way as the density of states. This result suggests that the coupling constant is proportional to the bare density of states. The present results of the density of states were compared with the theoretical ones which were deduced by Mattheiss for Ta and W.

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The behaviours of the various dielectric properties and specific heat of potassium selenate, K₂SeO₄, have been studied with particular reference to the transitions at 129.5°K and 93°K. Below 93°K the crystal is ferroelectric along the c axis. The spontaneous polarization and coercive field determined from the hysteresis loop are 6.5×10⁻⁸ coul/cm² and 60 V/cm respectively at 80°K. The curve of dielectric constant vs temperature obeys the Curie-Weiss law above the Curie point and the Curie constants for warming and cooling processes are 27°K and 30°K respectively. The Curie temperature varies almost linearly with the biasing field with the coefficient of 0.19°/kV/cm. Effects of the γ-radiation on the dielectric behaviour are observed. Discontinuity of the specific heat of about 2.3 cal/mol·deg has found at the transition of 129.5°K. Anomaly at the transition of 93°K is very small. The transition energy and the entropy change are estimated to be of the order of 0.5 cal/mol and 5×10⁻³ cal/mol·deg of less respectively. The higher temperature transition is of second order and the lower of first order.

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Single crystals of ferroelectric AgNa(NO₂)₂ were grown from aqueous solution containing proper amounts of NaNO₂ and AgNO₂, and dielectric properties were measured. The dielectric constant along the b-direction ε_b at 1 kHz shows a sharp maximum at the Curie point of 38°C. Above the Curie point, ε_b obeys the Curie-Weiss law with the Curie constant of 4.7×10³°K. The ferroelectric-to-paraelectric phase transition is of the first kind. A conspicuous dielectric dispersion is observed in the frequency region of 1 kHz∼1 MHz. Ferroelectric hysteresis loops are observed in a narrow temperature range of about 2°C below the Curie point. Difference between the tansition behaviors of AgNa(NO₂)₂ and NaNO₂ is discussed. A picture of the composition dependence of the transition points in NaNO₂–AgNO₂ system is given from differential thermal analysis measurements.

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A mechanism of the spin-lattice relaxation of the conduction electrons in InSb is presented. The effective spin-reversal Hamiltonian is originated from the interference effect between the spin-reversal interaction proposed by Pavlov and Firsov and the electron-phonon interaction. These two interactions are connected with the longitudinal polarization wave. Temperature dependent part δH(T) of the ESR line width for the sample of high electron concentration N>5×10¹⁴/cm³, is related to the spin-lattice relaxation time T₁ by δH=h⁄gμ_BT₁. Here δH(T)=ΔH(T)−ΔH(0) and ΔH(T) denotes the line width at temperature T. Origin of ΔH(0) is not clear yet. Calculated relaxation rate can provide a qualitative explanation of the observed values by Gershenzon et al..

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Measurements of the Knight shift and quadrupole coupling parameters of the ⁴⁵Sc and ⁵⁵Mn nuclear magnetic resonances are reported for the hexagonal Laves phase compound ScMn₂. This spectrum furnishes an example in which combined Knight shift and quadrupole interactions of less-than-axial symmetry occur.

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A formula which is convenient for the calculation of piezoabsorption spectrum is derived. By applying the formula to the π-bands of graphite, the piezoabsorption near 4.8 eV peak is calculated numerically, and some corrections of the previous result for the absorption are also made. The results are compared with those of thermoreflectance measurement; discrepancies between the theory and the experiment are discussed in connection with the choice band model.

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The small-signal permittivity of the (100)-type 180° domain wall in BaTiO₃ is calculated relative to the signal-domain permittivity according to a previously-reported microscopic model of 180° domain walls in BaTiO₃. A perturbation approach is developed which makes use of the known zero-field solutions of this domain wall and the single domain.
It is found that the (100) domain-wall permittivity is about (Remark: Graphics omitted.) larger than the single-domain permittivity, and there are two reasons for this effect: First, the internal fields and polarizabilities of the ions in the wall region differ from the single-domain values; and second, the presence of a field lowers the domain-wall symmetry promoting the polarization of the Ba and O_b ions on the (100) domain-wall plane. The dominant contribution to the enhanced domain-wall permittivity is the induced Ba and O_b polarizations.

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The upper branch of the polariton dispersion curve has been experimentally obtained by measuring the thermal emission spectra of thin films of LiF at oblique emission angles. The formulation based on the virtual mode theory is given for determination of the dispersion relation. The dispersion curve has been obtained from the resonance frequency and width of the thermal emission due to 0 TH mode which is the lowest mode at higher frequency region than LO frequency.
Measurements have been performed at temperatures 420°K and 605°K and at emission angles ranging from 45° to 80°. The results agree fairly well with the theory.

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The tetragonal phase of nickel chromite (NiCr₂O₄) was investigated by X-ray diffraction method for single crystal. The {110} twin structure was found, below the transition temperature (29°C), as a result of the tetragonal domain formation due to the Jahn-Teller distortion. The twin angle was observed to vary in accord with the temperature dependence of c/a and to be about 1.1° and 1.6° at T=21°C and T=−30°C, respectively.

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An X-ray study with CuKα was carried out on a fine-powder sample of GaAs. Relative intensities of 11 lines from the 111 to the 620 were measured and the scale factor was determined from absolute intensities of the 111 and the 220. Form the three-dimensional difference Fourier synthesis on the (110) plane, two sorts of peaks were found in Δρ(x, y, z). One lies near (1/8, 1/8, 1/8), which is the midpoint of chemical bond between Ga and As. This peak seems to correspond to a covalent bond. The other lies near (1/2, 1/2, 1/2), which is the position of anions in the NaCl structure with a cation at the origin. It may be possible that this latter peak corresponds to the ionicity of the bond.

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The phase transition that KMnF₃ exhibits at T_c=184°K has been studied in detail by X-ray scattering. The anomalous scattering that accompanies the transition near T_c is found to be anisotropic for q∼0.05Å⁻¹. For these wave vectors therefore, the Ornstein-Zernike approximation for the density-density correlation function cannot describe the critical properties. The temperature dependence of the square of the frequency of the soft Γ₂₅ mode at R is found to be reasonably well described by a Curie-law divergence. The space group of the condensed phase of KMnF₃ has been reexamined. The space group is found to be the tetragonal I4⁄mcm (D_4h¹⁸) rather than the orthorhombic Pbnm (D_2h¹⁶) proposed by Beckman and Knox. The space groups of the condensed phases of KMnF₃ and SrTiO₃ are therefore identical.

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Effects of inelastic scattering on the diffraction of fast electrons by a crystal are studied. The Bragg reflections of both elastically and inelastically scattered electrons are considered. The absorption coefficients of wave fields and their dependence on the diffraction condition are derived. The results of the theory are applied to the intensity distributions of “equal thickness fringes” in electron microscopic images formed by elastically and inelastically scattered electrons. The effects of the interband and the intraband transitions on the images formed by inelastically scattered electrons are studied. The applications of this theory to the thick-crystal and the multiple scattering are discussed.

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L-level widths due to the Auger and radiative processes are calculated for light metals such as Al, Mg and Na by using a theory of soft X-ray emission developed by Morita and Watabe in terms of the Green’s function method. Results are nearly consistent with level widths observed experimentally. It is explained that L₁–L_2,3 emission line spectra have very weak intensities and L₁-emission band spectra cannot be observed. The calculated intensity ratios between L₃- and L₂-emission band spectra are nearly equal to two, the degeneracy ratio of these two levels, while the observed intensity ratios are much larger than two. It is suggested that the observed large values of the ratio may be attributed to the self-absorption effect on the L₂-band emission.

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Revised calculations for the fourth moments ⟨R⁴⟩ of the end-to-end distance of polypeptides in the helix-coil transition region (M. Go, N. Saitô and M. Ochiai: J. Phys. Soc. Japan 22 (1967) 227) are given. The deviation from Gaussian distribution is found to be smaller compared with the previous calculation, but exhibits a peculiar behavior. This behavior is discussed in detail. The effect of an external force on the helix-coil transition (N. Saitô and M. Go: J. Phys. Soc. Japan 24 (1968) 376) is not subject to a great alteration in the revised calculation.

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Investigations as carried out on the viscous behaviour of liquid crystals of the cholesteric type viz., cholesteryl acetate, cholesteryl formate and cholesteryl benzoate throughout their anisotropic and isotropic phase using a cone-and-plate viscometer. It is observed that there is a noticeable abrupt change in the viscosity at the transition temperature in the case of cholesteryl acetate and cholesteryl benzoate, whereas a very slight variation is observed in the case of cholesteryl formate. The activation energies are calculated for the cholesteric and isotropic phase and the abrupt change in viscosity at the transition temperature is attributed to the hige mobility of the cholesteric mesophase of these esters.

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The interchange instability of rotating plasma is investigated from the thermodynamic point of view. The rotation of plasma tends to stabilize itself in the negative δY configuration, where Y=∫(r²⁄B)dl⁄∫(1⁄B)dl. In the negative δ∫(1B⁄)dl configuration with negative δY property the rotating plasma is more stable than the non-rotating one. An example of the negative δY configuration is exhibited.

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A relativistically invariant formulation of the Boltzmann equation with collision terms is established on the basis of elastic binary collisions. The collision cross sections to be used are those obtained in relativistic quantum mechanics. The theory is applied to plasmas of Boltzmann statistics. The Coulomb divergence arises in the same way as in the nonrelativistic case, and the cutting-off is indispensable which neglects the effects of distant collisions. The covariant Landau equation is obtained for the electron and electron-proton plasmas. The impulse approximation is discussed in connection with the Coulomb divergence involved in the derivation of the Landau equation.

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Strongly ionized, hot electron plasmas are produced by unmodulated, high power electron beam interaction with plasmas, of which properties have been investigated both experimentally and theoretically especially on characteristics of waves excited. When the plasma is considerably quiescent in a region of small beam power, low frequency ion plasma wave (∼several MHz) is found to be excited by a coupling with slow cyclotron wave of the electron beam. Besides this, in addition, weak excitation of high frequency oscillations (∼1 GHz) occurs in this region presumably due to a coupling between electron cyclotron wave of the plasma and slow cyclotron wave of the beam. In a turbulent plasma state above a certain critical beam power, on the one hand, plasma hybrid wave interaction with beam slow waves becomes essential for the plasma instability exciting powerful high frequency oscillations (∼several GHz), which seems to lead to production of strongly ionized plasmas.

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It is shown that successive excitation of two cyclotron waves with a time interval longer than their cyclotron damping periods leads to a spontaneous appearance of a longitudinal plasma wave in a collisionless plasma. The longitudinal plasma wave (i. e., the echo), has the frequency shifted by the cyclotron frequency and appears at the same time as in the case of the excitation by two plasma waves. The line shapes of temporal echoes, together with the phase mixing processes of the second order distribution functions, are studied numerically.

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A new perturbation theory based on a canonical transformation for solving the Vlasov equation is developed. The theory is designed to cope with time secularities. The method is based on the transformation of orginal system to the new system where the particle is in free motion, that is, the transformed Vlasov equation is of free streaming. Practical calculation is systematic but restricted to the second order approximation in the expansion parameter (wave potential energy/particle kinetic energy). The result is used to obtain Fokker-Planck type equation, and a velocity space diffusion coefficient is obtained.

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A method of treatment is put forward for dealing theoretically with the three-dimensional axially symmetric vortical field of flow of a compressible viscous heat-conducting field. The method of numerical integration is applied iteratively to the rigorous equations of motion and of energy under simplifying conditions: u=u(r), v=v(r), w=zf(r) and p=(1⁄2)cz²+p₁(r) for the distributions of velocity components and of pressure, in cylindrical coordinates, the only approximation being concentrated in an assumption of ρ=ρ(r) for the distribution of a mean value of density. The temperature distribution in the vortex field then takes the form T=T₁(r)+z²T₂(r). Examples are obtained which show distributions of total and static temperatures in vortical fields of flow and comparison is made with the result of experiments in a Hilsch tube. Discussions are made on the mechanism of variation of mechanical and thermal energy in the vortex motion of a real fluid.

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