The differential scattering cross sections of Li–D neutrons were measured for 11 elemens at scattering angle of 90 degrees.
The neutron detector was an ionization chamber connected to an electrometer whose energy sensitivity can be changed to some extent by the Change of filling gas and its pressure.
Intensities of scattered neutrons observed with the chamber filled with high pressure methane, whose sensitivity is expected to be nearly constant through the energy region concerned, agreed well with the values calculated from the differential scattering cross sections which were assumed to be equal to σ⁄2·1⁄4π, σ being the total cross sections.
Intensities of scattered neutrons observed with hydrogen filled chamber with greater sensitivity at lower energy side showed 30 to 60% higher values than expected by the same calculation.
These results support the view that (1) half of the total cross section is “capture scattering”, and (2) in “capture scattering” process, neutrons are scattered isotropically with less energy than the primary neutrons.

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We take new non-linear approximation for the interatomic force in a solid. We calculate the thermal expansion of some materials, and get good agreement with experiment. And it is easily shown that using this non-linear potential conserves type of partition function of linear model.

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Field-polarization hysteresis loops of ceramic barium titanate at high frequencies have been observed by a cathode-ray tube. To prevent the temperature rise due to hysteresis loss, pulsed voltage was used. The frequency was increased up to the order of 1 Mc/s, but the loop has not shown any drastic change, except the gradual decrease of the maximum polarization and of the average slope of the loop. The temperature dependence was also examined between the room temperature and about 150°C.

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The effect of the use of pulsed voltage on the hysteresis loop was examined using rectangular pulses at the frequency of the order of 10 kc/s. Initial transient phenomena in obtaining a dynamical hysteresis loop was studied using pulses with very small number of swings. The characteristic shape of the loop for pulsed voltage was found to correspond to the initial stage of the loop for continuous voltage. The remanence and its decay could be directly observed oscillographically.

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The superlattice formations in ternary alloy with body centered cubic lattice are discussed by taking into account the interactions between nearest neighboring atoms as will as those between next nearest neighboring atoms. On the besis of this theory the possibility of the various types of superlattice formations in ternary alloy is inferred. The experimental data on the superlattice formation in Cu-Mn-Al system are discussed from this point of view.

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The magnetostriction, internal friction and Young’s modulus have been measured for usually annealed and field-cooled 65-Permalloy and Perminvar. The magnetostriction shows the degree of the effect of field-cooling. The behavior of internal friction of 65-Permalloy shows remarkable difference from that of Ni₃Fe which had previously been observed and explained by the theory considering the rotation of the spontaneous magnetization. It can be explained neither by considering the rotation of the spontaneous magnetization nor by considering the displacement of 180° domain boundaries, so that the other process must be introduced to explain the experimental facts. The internal friction of Perminvar shows intermediate character between Ni₃Fe and 65 Permalloy. It is supposed to be explained by considering both the rotation of the spontaneous magnetization and the other process which is responsible for the internal friction of 65-Permalloy. The change of Young’s modulus by the magnetization is consistent with that of internal friction.

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In this part, the method described in the preceding part is modified to treat equaly A and B atoms. The chain approximation is employed in the present part, as previously. If the interactions are considered in appropriate manner, the present method gives the same critical temperature as those obtained from Bethe’s approximation for most types of lattices. The exceptional cases are the critical temperatures of order-disorder transition in triangular and face-centered cubic lattices. The formulas to express the propagation of order in crystal lattices are obtained in closed forms. And for the cases of simple lattices the formation of the superstructure is discussed.

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The theory of diffuse scattering of X-rays by binary alloys is developed, based on the pair distribution functions of atoms which have been given in the previous parts of this series and which are entirely similar to those appear in the theory of imperfect gases. These distribution functions enable us to perform the theoretical calculation of the distribution of the diffuse intensity of scattered X-rays due to the short range order at the temperature above the critical temperature, and the calculations are carried out both for the case of the order-disorder systems and for the two-phase separation systems. The disk-like shape of the diffuse maxima observed for Cu₃Au is predicted from this theory. And it seems that such anomalous shape does not appear in the case of two-phase separation system.

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The electronic structure of the ground state of CH₃ is investigated by the Heitler-London-Slater-Pauling method extended by Voge and Kotani and Siga. The wave functions are constructed without assuming the electron pair bond and taking (2s)²(2p)², (2s)(2p)³ and (2p)⁴ configurations of the carbon atom into account. Assuming a pyramidal model for this radical, seventeen ²A₁ states are obtained. The energy matrix for these states is computed by means of the representation matrices of the symmetric group. Solving the secular equation thus obtained for various values of the apex angle, the most stable configuration is found to be slightly nonplanar. The electron pair bond approximation is shown to be fairly good in the cases when ∠HCH=120° and 109.5° (sp² and sp³ hybridization), but it becomes very poor for ∠HCH=90° (pure p bond).

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The theory on the static repulsive force between two charged colloidal particles was established by Verwey and Overbeek (1948). However, as the theory was given in a rather intuitive way, there have been some doubts about its strictness.
In this paper, the expression of the free energy obtained by using V.-O.’s first method is given in a strictly statistical mechanical way; no correction is necessary such as Levine (Proc. Cambridge Phil. Soc. 47 (1951) 217) considered to be.
Two new correction terms are added to V.-O.’s formulae obtained by their second method. One of them is added to cancel the effect that charges still remain on the particle surface when the surface potential is kept constant and the charges of ions vanish. The other is added when the adsorbed ions on the surfaces are kept fixed and the charges of ions vanish, to cancel the effect that the concentrations of ions between two parallel plates are different from the normal concentrations at infinite distance from the plates.

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A method to determine the electron temperature and the field strength of high frequency discharge plasmas is given. It is a modified floating double probe method, where the double probe consists of a rod probe and a forked probe. By this method argon discharges in the region between 0.26 and 1.0 mm Hg at 170 Mc/sec have been studied. The electron temperatures and the field strengths were measured as a function of the radius of discharge tubes and compared with theoretical equations. The obtained results were approximately equal to those of direct current discharge.

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The oscillatory phenomena are observed in a hot cathode discharge tube like fluorescent lamp. The oscillations occur in the vicinity of the anode, and are the periodical variation of the anode fall accompanied with a sudden ionization. The characteristics of the oscillations depends on the anode conditions as well as the thermoionic emissivity of the cathode.

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In regard to the mechanism of the oscillatory arc in a hot cathode discharge tube like fluorescent lamp, the circumstances was made clear as follows.
The oscillations occur in the following cases. That is, (1). The quantity of the positive ions generated by ionization in the anode fall is greater than that necessary to sustain the arc, and (2) the arc current is smaller than the saturated electron current determined by the cathode temperature.
Accordingly the existence of the excess ions is the cause of the oscillations. Ionization and diffusion occur alternately. Therfore the characteristic of oscillation is determined by the quantity of excess ions. But in this case it is also influenced by the space charge in front of the cathode, that is, by the thermoionic emission of cathode. And generally a fraction of the excess ions will be employed to reduce the anode fall stationarily, if the electron emission becomes to be limited by its saturation value or by the negative space charge in front of the cathode.

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From the recurrence formula of Weinstein a matrix equation is derived connecting the amplitudes of electric vector of light in the k-th layer with those in the p-th layer of a multi-layer film. The elements of the matrix are expressed as functions of the reflection and transmission of the intermediate film between the media k and p. From this equation, formulas are derived for the transmission and reflection of an arbitrary multi-layer filter as functions of the thickness of the spacing layer. The results are found out to be of the same form as Abelé’s equations derived by the consideration of the multiple reflections in the spacing layer. By these equations, the physical meaning of the complicated phase factor of Vašicek’s equation is made clear and some new relations of the intensity and phase of the transmitted and reflected light are obtained.

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In order to clarify the detailed structure of turbulence, measurements were made on the fluctuation of spectral component which is the output of band-pass filter. Using a voltage integrator and a counter-chronograph, two quantities were observed in the so-called isotropic turbulence produced by a grid in a wind-tunnel.
One is the distribution function of amplitude averaged in a certain time interval. Dispersions of distribution under various experimental conditions are computed and compared. The other is the time correlation function of fluctuating output. The magnitude of correlation is not so small even for a time interval of 0.5 second and curves seem to be classified into two groups according to the central frequency.

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The quantitative analyses of gas, evoled from commercial and electrolyticnickel were carried out by means of the micro-gas analyser, whose principle is similar to Prescott and Morrison’s apparatus. The main components of the evolved gas were carbon mono-oxide, carbon dioxide, hydrogen, water vapour and nitrogen. The rate of evolution of carbon oxide was found to be determinated by the diffusion of oxygen atoms through metal. A considerably large amount of gas was evolved from the electrolytic nickel, but below 450°C only hydrogen was released, while at higher temperature some other kinds of gas were extracted. The activation energy for degassing of hydrogen were about 5 Kcal/g. atom and 12 Kcal/g. atom for low and high temperature regions respectively. This suggests that there are two mechanisms for the diffusion of hydrogen: one is the normal lattice diffusion and the other is the rift or crystal boundary diffusion.

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An electron diffraction camera provided with a rotating sector was designed, constructed and tested. Though it has no specially original feature, it is simpler compared with that used in the United States and can be constructed at a little expense. A preliminary result was obtained with polystyrene films and was analysed after the method developed by J. Karle and his coworkers. It showed that this equipment was quite satisfactory in its functions.

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A direct reading flow-meter for the measurement of Q-value in vacuum technique is described. The principle of the meter is to measure the force exerted on a disc placed in a vacuum piping. The kinetic theory shows that the force acting upon the suspending plate, due to the thermal motion of molecules, is stronger than one supposes and this is proved by the experiments. Flow-meters of suspension type are made and tested. The highest sensitivity available is 1×10⁻³μHg. litre/sec per 1 mm. of scale. The application of this meter to measurement of pumping speed, measurement of desorbed gases, vacuum drying and leak detection are described.

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The phenomena of failure and fracture of metals were treated as a Markoff process or chain. In the fundamental types of failure and fracture, the physical meanings of transition probabilities were interpreted and they were found to correspond to the nucleation rate or reaction rate. The following fundamental features were unifiedly interpreted: (1) the dependence of strength on stress velocity or deformation velocity and temperature (2) the dependence of the time for creep fracture on stress and temperature. (3) many features in the endurance limit and the dependence of the number of repeated cycles for fatigue fracture on the stress range (4) the size effect (5) the fluctuation characteristics (6) ductility transition phenomena.

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The occurrence of the change of fracture from ductile type to brittle one which is often called ‘cold brittleness’ is studied from the standpoint of the stochastic theory. In the present paper failure and fracture processes were treated as reaction rate process. The relation between deformation velocity, V_B, and the absolute temperature for brittle fracture was obtained as the form:
logV_B=−\fracQRT+c₀.
The effect of radius of notch on the transition, the size effect, and the scatter of the brittle strength were also interpreted from the same standpoint. In the case in which the Cottrell-Bilby mechanism for yielding, and nucleation process for brittle fracture, respectively, are regarded as rate-determining, similar results can also be obtained.

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The accurate measurement of the half-life of ThC′ was made by the pulse timing circuit method using a G-M counter and a proportional counter. The value of the half-life was found to be (2.9±0.1)×10⁻⁷ see. Some details of the pulse timing circuit used are explained in this paper.

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Surface oxidation products on various alloys due to varying oxidizing conditions within the range of 300–900°C for temperature and 10⁻⁴–760 mmHg. for air pressure are studied by the electron diffraction method. Alloys studied are copper alloys containing 0.3% Be, 0.5% Al, 0.1% Mg, 7% Mn and 7% Ni and that of iron with 13% Al respectively.
The selective oxidation or the phenomenon that the baser component of alloy is oxidized selectively in spite of its much lower content in the mother alloy than the other was found to occur generally in these alloys when the air pressure is sufficiently low and the temperature is high enough. High yield of the secondary electron emission of Be-Cu alloy is concluded to be due to the selective oxidation product BeO having a particular orientation grown on this alloy. An unknown oxide of Ni of a spinel type structure is found on 7% Ni-Cu alloy.

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Ultrasonic waves propagating in a transparent medium can be considered optically as a sort of phase grating. Therefore, the method of phase microscopy may be applied to the image formation of ultrasonic waves. We have studied theoretically and experimentally the application of the phase method in visualizing ultrasonic waves and confirmed the effect of the method for the improvement of the visibility of the image. In the usual Schlieren method for visualizing ultrasonic waves, the zeroth order diffraction image is perfectly screened, while in our method the image receives a proper absorption and phase retardation by the phase plate placed in the diffraction plane. According to the theoretical calculations, the phase retardation for the maxium visibility of the image of progressive waves with the stroboscopic illumination is π⁄2 and the optimum absorption varies with the intensity of the waves. In both cases of the usual method and the present phase method, the theoretical curves are compared with the experimental results, showing a considerable agreement between them. Further, the fine structures in the images are seen with the increase of sound intensity.

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