The photonuclear reaction cross section of Cu⁶³(γ, n)Cu⁶² has been frequently used as the standard for the (γ, n) reactions, but the measured values by many workers do not agree with one another and can be roughly divided into two groups, namely, about 100mb group and about 50mb group. It appears that the former group contains the values obtained mainly by measurements by use of bremsstrahlungs, while the latter those obtained mainly with Li–p γ-rays.
We attempted to re-determine the (γ, n) cross section for copper, zinc and silver by Li–p γ-ray. Absolute measurement of γ-quanta was performed by Hough’s method, and reaction yields were determined by the activation method in which the absolute numbers of activated nuclei in samples were determined by measuring the β-ray with a 4π-proportional counter and applying the “method of extrapolation”. The cross sections of Cu⁶³, Zn⁶⁴ and Ag¹⁰⁹ for 17.6 Mev γ-rays were found to be 42.5 mb±15%, 23.3 mb±18% and 61.5 mb±16% respectively. Experimental cross sections so far obtained by many workers are compiled in Table II and some discussions are given.

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The gamma rays resulting from the ring scatterers of Mg, Al, Fe and Bi bombarded with 2.95 MeV neutrons have been investigated. The cross sections for the 0.845 MeV gamma ray from Fe⁵⁶ and for the 1.37 MeV gamma ray from Mg²⁴ were 1.10±0.13 and 0.66±0.10 in barns respectively. The angular distributions of the gamma rays relative to the direction of the incident neutrons were both symmetric around 90°. These cross sections and angular distributions were compared with the statistical theory by the optical model. Our results were fairly well interpreted by using a diffuse potential well.

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The alpha particles from the reaction F¹⁹(p, α)O¹⁶ resulting in the ground state of O¹⁶ have been measured, making use of a proportional counter method.
The excitation curve has been measured at a laboratory angle of 50° from 12.9 to 14.1 Mev. The. curve changes smoothly with incident proton energy. The angular distributions of the alpha particles have been measured at 14.2, 13.5, 13.0, 12.0, 11.0, 10.0, 9.0, and 8.0 Mev, which can be qualitatively explained by the simple triton pickup theory. Although fairly good agreements with the theory can be seen at 14.2, 13.5 and 9.0 Mev, the angular distributions for the other energies deviate from the theory to some extent. The deviation is generally larger for backward angles and especially at 11.0 and 8.0 Mev striking backward peaks are observed. It is considered that for detailed explanation of the results, refinement of the theory or introduction of other processes of the reaction or both are required.

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Making use of a proportional counter, alpha particles have been observed from the reactions Al²⁷(p, α)Mg²⁴ resulting in the ground and first excited states of Mg²⁴ and Cr⁵²(p, α)V⁴⁹ resulting in the lowest three and a few higher states. Excitation curves have been measured at a laboratory angle of 50° with respect to the bombarding beam, from 12.7 to 14.1 Mev for Al²⁷(p, α)Mg²⁴ and from 9.0 to 14.8 Mev for Cr⁵²(p, α)V⁴⁹. The former shows a sharp energy dependence, while the latter shows a fairly smooth structure. Angular distributions have been measured at 14.1, 13.0 and 12.8 Mev for Al²⁷(p, α)Mg²⁴ and at 14.2, 13.0, 12.0, 11.0, 10.0, 9.5 and 9.0 Mev for Cr⁵²(p, α)V⁴⁹. Although the Al²⁷(p, α₀)Mg²⁴ data can be partially fitted by [j₂(Qr₀)]² of Butler’s theory, some angular distributions show strong backward peaking. Either interference between various direct interaction processes or between direct interaction and compound nuclear processes, or both are responsible for this reaction. The approximate 90° symmetry of Cr⁵²(p, α)V⁴⁹ angular distribution does not appear to be inconsistent with the statistical theory of nuclear reactions. However, the conspicuous forward peak at higher energies, especially at 14.2 Mev, is considered to indicate the increasing contribution of direct interaction processes.

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The Brownian motion of a classical harmonic oscillator is treated mechanically throughout. The oscillator is coupled with thermostat which is composed of a great number of harmonic oscillators. By use of a transformation which eliminates the coupling to the first order, the second order quantities like the friction force in obtained. Correlation of random force is also discussed.

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The thermoelectric power of AgCl doped with several concentrations of CdCl₂ is measured and compared with the theory.

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Ultrasonic attenuation in megacycle range for cold-worked and for quenched KCl crystals has been measured against temperature between 200°K and room temperature. A very broad relaxation band appears below 240°K for cold-worked crystals. The experiments on the anisotropy of attenuation in crystals cold-worked by uniaxial compression demonstrate that the attenuation is caused by the motion of the dislocations. The activation energy is found to be 0.44 eV. Quenched crystals show also a similar band. The following are very unique features: As quenching temperature is raised the attenuation band shifts to higher temperature. This shift is accompanied by the increase of the activation energy. Another significant nature is the ageing effect, which results also a band-shift to higher temperature with increasing ageing time after quenching.
It has been discussed that the effects of vacancies in the dislocation core upon the activation energy for the motion of dislocations and the concurrent motion of vacancies in the cores of oscillating dislocations both give rise to such a broad band as observed.

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The deformation of the lattice around F and V₁ (the Seitz’ model) centers in alkali halides is determined from the experimental data on the difference between two ionization energies (optical and thermal) of these centers. In the process of the determination, we apply the method which has been developed in the previous paper (J. Phys. Soc. Japan 13 (1958) 153). We find that the lattice deformation is rather small in the case of the F centers, but very large in the case of the V₁ centers.

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Extending the previous treatment of the author on the bond alternation in infinite conjugated systems to finite systems, it is investigated why the wave-lengths of some homologous series appear to tend to infinity while those of others to finite limits when the number of carbon atoms increases. It is concluded that the bond alternation does not occur in shorter symmetrical or slightly unsymmetrical chains, while, in strongly unsymmetrical chains, the bond alternation always occurs and that it always occurs in longer chains according to the result in the previous paper.

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Nernst coefficient, magnetoresistance, and magnetothermoelectric power together with electrical conductivity, Hall coefficient, and thermoelectric power of α-Ag₂Te are measured as functions of the e.m.f., E of the galvanic cell Ag|AgI|Ag₂Te|Pt, where E may be considered to represent the relative position of the Fermi level in the Ag₂Te specimen. The experimental results exhibit consistent agreement with the Lorentz-Sommerfeld theory for degenerate two-band semiconductors with energy independent mean free paths of carriers. Relative thermal conductivity is also measured, showing minimum at a E value expected from the theory.

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In crystalline 1-3-5-triphenylbenzene every four molecules form a pseudo-hexagonal orthorhombic unit cell with the [100] as the pseudo-hexagonal axis. The deviation from hexagonal symmetry which is only 0° 19′ is discussed in terms of both the crystal structure and the diffuse scattering reflections shown by a Laue photograph taken with the X-ray beam parallel to the [100] axis. Two other Laue photographs with the X-ray beam parallel to the [010] and [001] axes are given. All the diffuse scattering reflections in the three photographs are indexed and the types of elastic waves (of thermal origin) affecting the crystal lattice are revealed.

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Methylamine chrome alum shows an antiferromagnetic ordering below 0.015°K–0.02°K and it is known that this ordering results from the magnetic dipole-dipole interaction among the chromic ions. The present paper investigates, on the basis of the molecular field approximation, the phenomenon of transition below the Néel point from the antiferromagnetic state to the paramagnetic state caused by an applied field, at constant temperature or at constant entropy. Depending on the direction of the applied field relative to the crystalline axes and also on the shape of sample, different behaviours of the transition are obtained. For a spherical sample three are studied, namely, the cases of H\varparallel[111], H\varparallel[100] and H\varparallel[10\bar1], and for an infinitely long sample two cases, i.e., the axis of the sample and H are both parallel to either [111] or [100]. In Appendix is given a summary of the previous theoretical study by Kanamori. Motizuki and Yosida of the same kind of antiferro-paramagnetic transition in two-sublattice antiferromagnet, in relation to the present investigation.

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A systematization was proposed for the determination of the crystal structure when the crystal consists of the molecules with known shape. The main feature of this method is to separate the refinements by the least squares at an early stage into (1) successive improvements of the position and orientation of the molecule and (2) correction of the molecular shape fixing the molecular position and orientation.
The result of the application of this method to the crystal of 2-amino azulene (a=11.62, b=10.76, c=6.32 Å, Z=4, space group Pbn2₁) was given.

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Experimental and theoretical considerations of segmental motion in chain molecules were studied from the view point of nuclear mognetic resonance.
By using the high resolution type spectrometer of NMR, it was verified that the line widths of phenyl group and CH₂ group in polystyrene-CCl₄ solutions were almost all independent of chain lengths in dilute solutions. These values of line widths indicate that the so-called segmental motion in a chain is performed in the unit of about ten monomers.
The segmental motion hindered by the potential field was discussed by using the generalized theory of Brownian motion. The influences of restricted motion upon T₁ and T₂ in polyisobutylene-CCl₄ solution are examined. The results of our theory are as follows. The activation energy of segmental motion tends to the activation energy of solvent when the concentration of polymer decreases. The value of activation energy increases with the increase of concentration of polymer. These results are in a good agreement with these of mechanical and dielectric measurements. Furthermore, the values of hindering potential are calculated from the data of T₁ and T₂ in PIB solutions.
Finally, it is verified that the rigidity of polymer solution in the high frequency measurement should be caused by the potential field hindering the micro-Brownian motion of segment.

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The general treatment developed in previous papers is applied to the case where the aqueous solution of polyvinyl alcohol is irradiated by gamma rays and the results are compared with Danno’s measurements. The behaviours of irradiated aqueous solution of polyvinyl alcohol before and after gelation are well explained by the author’s general theory. It is concluded from the analysis that end-linking instead of cross-linking occurs in the solution and also that only one molecular end out of the two which are produced by molecular scission of a polymer links with a monomer unit of another polymer molecule. It is also shown that if any impurity, especially oxygen, is not contained, the intrinsic viscosity of polyvinyl alcohol increases with radiation dose.

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The effect of impurity on cross-linking or end-linking of an irradiated polymer is discussed theoretically. It is shown that the radiation effect on a pure polymer can be found by measuring the intrinsic viscosity and the gel point of an irradiated polymer containing an impurity. The theory is compared with Chapiro’s measurements. One of the important results is that when impurity hinders cross-linking, all the relations between physical quantities of an irradiated polymer containing impurity can be reduced to those of the polymer containing no impurity, if use is made of a reduced radiation dose instead of the real dose. This is not the case for the effect of impurity on end-linking. Such a difference is expected to enable us to distinguish between cross-linking and end-linking.

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A new type of antiferromagnetic spin arrangement, which is theoretically possible in the rutile type crystal and seems to be realized in polianite, MnO₂, is proposed. This spin arrangement, which will be named the screw-type structure, consists of spins screwing along the four-fold crystalline axis. The stability ranges of this and other spin structures are studied, assuming three different exchange interactions. The magnetic properties of the screw-type structure, including the anisotropy energy due to dipolar interaction and that due to crystalline field, the susceptibility, the spin waves, and the neutron diffraction pattern, are studied. Neutron diffraction data for polianite obtained by Erickson (unpublished) can well be accounted for by the screw-type structure with a pitch of (7/2)c. The magnetic properties of the MnO₂ crystal are discussed on the basis of this 7/2-pitch-structure.

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As previously reported, two or three plasma-electron oscillations of slightly different frequencies are simultaneously generated in a hot cathode discharge. The filled gas is mercury vapour at pressures of order of 1 micron. These oscillations can be observed by a Yagi antenna set apart from the discharge tube as well as by a probe in it. In the discharges the primary electrons form convergent and divergent beams. The oscillation of the highest frequency is generated by the convergent beam in the central part of the tube and this is that observed by many authors. The oscillation of the lowest frequency seems to be generated near the wall of tube by the divergent beam. Another oscillation having a middle frequency is often observed. This is generated at the periphery of the convergent beam.

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In this paper, the phenomena of viscous-inviscid interaction effects at M_∞=6.2 over the front part of bodies have been investigated. The models tested are a flat plate and wedges having a plane, a convex or a concave surface, respectively. A uniform flow of R_∞=2.0×10⁵ per cm was established using a divergent shock tube. The measurements of the flow field were made by optical methods (interferometer and schlieren photograph), and in order to supplement the data the X-ray technique was employed near the leading edge of the model.
The results are as follows. (1) For a flat plate: i) the pressure distribution on the sharp-nosed plate is about 5 per cent higher than Nagakura-Naruse’s theoretical values; ii) the boundary layer thickness agrees almost perfectly with Naruse’s theoretical values; iii) the shock wave location is in good agreement with the empirical formulae of Kendall and of Bogdonoff and Hammitt. (2) For wedges: i) near the leading edge, the boundary layer growth on a concave wedge is more rapid than that either on a plane or a convex wedge; ii) except in the region close to the leading edge, the influence of leading edge bluntness on boundary layer growth is significant in the order of convex wedge, plane wedge and concave wedge; iii) except in the region very close to the leading edge, the pressure distributions at the front parts of the plane and convex wedges are in fairly good agreement with the values predicted by inviscid theories (characteristic method, tangent-wedge approximation, Newtonian-plus-centrifugal-force approximation and hypersonic small disturbance theory), but considerable discrepancies are found at the rear parts; iv) for the concave wedge, agreement is rather better at the rear part of the body than at its front part.

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The relations between the drag coefficient C of lattice of many parallel circular cylinders and Reynolds number R were studied experimentally. The drag of the specimen falling in a tower was measured in the region of R=ca 0.25∼1.0. If C vs R curve of a cylinder by Wieselsberger is used as standard, C vs R relations of lattice are approximately the same as Wieselsberger’s, when h⁄d=250 and 125, with d being the diameter of the cylinder, and h the distance of the centers of the two cylinders. Accordingly it is seen that Imai’s formula on the basis of the combination of Stokes’ and Oseen’s approximations is better than Tomotika and Aoi’s formula on the basis of Oseen’s. The C vs R relations of lattice, when h⁄d=50, 25 and 12.5, are somewhat similar to Fujikawa’s C vs R curves of two parallel cylinders.

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Wake development behind circular cylinders and flat plates was investigated in the research water tanks. The aluminium dust method was used to observe the flow patterns.
At the intermediate Reynolds number range the Kármán vortex streets are formed in the wakes behind cylindrical obstacles. But these primary Kármán vortex streets are not stable. They are more and more deformed as the distance from the obstacle is increased, and finally break down.
Thereafter, however, the wake in most cases begins to rearrange itself again into a configuration of the Kármán vortex street. The dimension of the secondary Kármán vortex street thus produced is much larger than that of the primary one. For the circular cylinder, when Reynolds number is lower than about 150, the ratio of the wave length of the secondary vortex street to that of the primary one is about 1.8 to 3.6, while it is about 10 when Reynolds number is higher than about 150.
Sometimes the secondary Kármán vortex street simply decays by viscous diffusion as it moves downstream, but in most cases it rearranges itself again to the next Kármán vortex street.

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