The energy spectrum of photoprotons from K³⁹ induced by 24 Mev bremsstrahlung was observed using nuclear emulsions. The observed spectrum does not agree so well with the calculated one using Weisskopf level density and classical Coulomb barrier height. The choice of a much lower Coulomb barrier height seems to give better agreement with the experimental result.
Structures are observed in the energy spectrum. These are discussed using various reaction mechanisms.

View full abstract

Gamma rays accompanying the decay of 25.0-day Sr⁸² have been investigated. Single and coincidence spectra taken with scintillation counter have shown the presence of gamma rays with energies of 0.69, 0.78 and 1.41 Mev in the decay of 1.25-min Rb⁸² and their relative intensities have been determined. Log ft values have been evaluated on the basis of the proposed decay scheme. The allowed beta transitions from the 1+ ground state of Rb⁸² to the ground state and the first and second 2+ states are found to be successively hindered, in accord with Sakai’s empirical rule. This problem is discussed in connection with the systematic trend of ft values in the neighboring nuclei. The E2/M1 mixing ratio of the 0.69-MeV gamma ray decaying from the second 2+ state to the first 2+ state have been determined from angular correlation pattern of the 0.78–0.69-MeV cascade and found to be −5.8₋₂₂^+5.5. The negative phase is consistant with the systematic trend of δ in the neighboring nuclei.

View full abstract

Thermal analyses are carried out for the specimens between 54% and 62.5% Mn. A phase diagram among ferromagnetic π-phase and ε- and β-phases is obtained, and it is pointed out that especially in the existence of the atomic ordering interaction, the locus of cross point of free energy curves is a good measure of the temperature from which the transformation starts. The following question is answered: “Why is π-phase produced by controlled cooling from Al-rich ε-phase but not from Mn-rich ε-phase?”

View full abstract

The moment generating function of a set of stochastic variables defines the cumulants or the semi-invariants and the cumulant function. It is possible, simply by formal properties of exponential functions, to generalize to a great extent the concepts of cumulants and cumulant function. The stochastic variables to be considered need not be ordinary c-numbers but they may be q-numbers such as used in quantum mechanics. The exponential function which defines a moment generating function may be any kind of generalized exponential, for example an ordered exponential with a certain prescription for ordering q-number variables. The definition of average may be greatly generalized as far as the condition is fulfilled that the average of unity is unity. After statements of a few basic theorems these generalizations are discussed here with certain examples of application. This generalized cumulant expansion provides us with a point of view from which many existent methods in quantum mechanics and statistical mechanics can be unified.

View full abstract

The scattering of charge carriers due to point imperfections having atomic radii different from those of host atoms is calculated for semiconductors, assuming the potential of scattering due to lattice strain to be a δ-function-like pseudo-potential for the continuous model approximation. From the calculation using the Born approximation, the interference between the strain scattering associated with the lattice distortion and the Coulomb scattering from charged centers has been found to be quite large, while no interference of scatterings between lattice vibrations and point defects has been deduced. This strain-interference effect must be an explanation of the difference in the electron mobilities between Sb-doped Ge and As-doped Ge.
The validity of the approximation method adopted and the effect of the free surface of crystal are also briefly discussed.

View full abstract

Domain patterns of single crystal films of iron, evaporated onto MgO cleavage surfaces, were observed by the Bitter technique. Epitaxy of them was perfect and the magneto-crystalline anisotropy constant K₁ of these films determined by torque measurement was almost the same as that of bulk materials. The observed domain configuration of the films is similar to that found on bulk crystals. However, some differences between them are caused from the thinness of the films. Predominance of the 90° walls and the configuration of two types of crossing of 90° walls in a cubic film are discussed. Using a new type of colloid, electron microscopic observations of walls were undertaken to find out their fine structure. From this observation it is confirmed that the walls in the films (<1000 Å thick) are the Néel type, and the Bloch lines should appear in 180° Néel walls. The reason why the cross-tie walls are not found in cubic crystal films is discussed.

View full abstract

The kinetic behavior of gold atoms in cadmium telluride single crystals has been studied at temperatures above and below 600°C. The diffusion coefficient was determined over the temperature range of 600°∼1000°C using autoradiographic technique by diffusing radioactive gold into cadmium telluride. The relationship between temperature and volume diffusion coefficient is found to be D=67exp(−2.0 eV⁄kT) cm²/sec. At temperatures below 400°C, the hole concentration in gold-doped crystals is observed to decrease by heat treatment, according to an equation N=N₀exp(−t⁄τ), where τ is a time constant dependent on temperature and dislocation density. It is shown that the experimental results are interpreted by the terms of the segregation of gold atoms to α and/or β 60° edge dislocations.

View full abstract

Green stripes are induced in WO₃ single crystals under a special heat treatment in the metallic vapor of Zn at a reduced pressure. Observations have been made of their various properties, which will be summarized under the following items; (1) Zn vapor and green stripes, (2) appearance of green stripes, (3) maximum temperature of heat treatment, (4) disappearance of green stripes, (5) orientations of green stripes, and (6) domain wall and green stripes.

View full abstract

Nuclear magnetic resonance (NMR) of Fe⁵⁷ in α-Fe₂O₃ was studied by using both the steady-state method and the pulsed NMR method. The signal could be observed in the temperature range, where the sample shows the parasitic ferromagnetism. From the experimental results it was concluded that the NMR signal of this sample is due to the nuclei within the domain wall. The average enhancement factor of the applied rf magnetic field was measured to be about 25,000. The spin lattice relaxation time (T₁) of Fe⁵⁷ was distributed between 3 m sec and 100 msec at room temperature, depending upon the intensity of the exciting rf pulse. The values of T₁ could be qualitatively explained by the relaxation mechanism due to the thermal domain wall fluctuation.

View full abstract

Electrical resistance of nickel films of the thickness from 140Å to 1600Å is measured as a function of temperature, and the Curie temperature of the films is determined from a break in resistance vs temperature curve. Residual gas is found to be effective in reducing the Curie temperature of the films when the ratio of pressure to deposition rate exceeds 1×10⁻⁶ mmHg·Å⁻¹·sec. A slight decrease of the Curie temperature is observed as a film thickness is decreased.

View full abstract

The dynamical theory of electron diffraction is extended to interpret the contrast of the electron-microscopic images of an edge dislocation perpendicular to the crystal surface. The wave function of electron passed through a region of a crystal is derived from an approximation that the electron wave travels in the region as if the neighbouring regions have the same lattice as that of the region concerned. The lattice distortion around the dislocation is replaced by a parameter which expresses the condition of diffraction. The intensity distribution of electron waves around the edge dislocation is calculated for the case of crystal image, lattice fringes and moiré fringes.
The calculated images are compared with the electron-micrographs and the coincidence between them is satisfactory.

View full abstract

Absorption spectra of heat treated thin silver films at incident angles 0°, 30°, 45°, and 70°, for both s- and p-polarized lights are determined by transmission measurement. It is found that the position of the absorption band near 2.6 eV observed for p-polarized light is shifted to the shorter wave length side when the angle of incidence increases. The fractional shift Δω⁄ω is of the order of 10⁻², and seems to increase with the film thickness. This phenomenon is explained from the view point of the k-dispersion of the local field in the two-dimensional distribution of small particles. The absorption spectrum due to polarization perpendicular to the film is presented.

View full abstract

An attempt is made to obtain, by the use of the simplified WKB method, the drag of wedge profiles with various apex angles at various subsonic speeds of the undisturbed flow. To do this, two types of dead-air model are considered: the flow past two flat plates with a dead air between them (Riabouchinsky’s flow) and the flow restricted by two infinite parallel walls containing an infinite dead air. Numerical calculation is performed for comparatively high subsonic flow of air. The results show that the simplified WKB method yields fairly good approximation even for the flow containing sonic speeds.

View full abstract