A comprehensive account of the author's X-ray and electron diffraction studies on precipitated cadmium sulphide is presented with the following mainconclusions. (1) The precipitates contain invariably stacking faults; precipitates of nearly pure α-CdS (hexagonal) from halide solutions and nearly pure β-CdS (cubic) from nitrate and sulphate solutions are the two extreme case.(2) The stacking fault concerned is ‘Jagodzinski's growth fault’. However, the occurrence of faulty sequences, hex. →cub. and cub. →hex., is comparatively rare. (3) The dependence of atomic structure of the CdS products on the salt solution used should be traced back to the ionic struc-ture of thesolution. (4) The general trend of crystallite-size and 'hexagonality' (fractionof the hexagonal stacking sequence in the crystal) of the CdS products can be understood on the basis of the kinetics of solid-phase formation. (5) The general trend of colour of the precipitate is reason-ably understood.
In a thermo-electric refrigerator, fin array for heat transmission must be of small dimensions and have high over-all heat transfer coefficient. Fora compact parallel fin array, approximate calculations of heat transfer coefficient are made for free convection and forced convection at a relatively low air flow rate of 50_??_300cm/sec. These values are compared with masured values, and heat transfer coefficient and optimum fin spacing are established in each case.
For electron injection into a betatron acceleration tube, there are an optimum angle of inci-dence and optimum position of electron gun to render the amplitude of electron osillation to a. minimum. In general, the oscillation amplitude of tangentially incident electrons becomes smaller as the field bumps are smaller, their phase angle in nearer π/2 and the voltage of incident elect-rons is higher. Hence, with a Kerst type magnet, the maximum X-ray output is easily obtained by placing the electron gun right under the magnet yoke, whereby the optimum angle of electron incidence becomes independent of the voltage of incident electrons and excitation current of the magnet. On the assumption that the X-ray output is proportional to he reciprocal of electron oscillation amplitude, the relation between the angle of electron incidence and the X-ray output can be explained.
The distribution of dose from a cobalt-60 slab irradiator for industrial use is calculated as a function of the distance from the irradiator. For a rectangular slab source, an approximate calcu-lation can be made by assuming thesource to be of a hypothetical form which can easily be treated mathematically. Two types of schematic models are conceived for the calculation of dose distribution: in the vicinity of the source, the slab source is assumed to be of an infinite length; away from the source, the source is assumed to be of a rod of a finite length. The measured values agree with the values calculated by taking the self-absorption of the source into account. The distribution of dose absorped in water of semi-infinite dimension that comes in contact with one side of the source is also calculated.
An apparatus for chemical reaction by irradiation of materials in liquid phase with Kr-85 as the source is devised. Circulation of bubbling Kr-85 gas through the reactant facilitates the reac-tion. In this method, the dose rate is controlled by changing the fractional void and concentration of Kr-85 gas. When 1000 ml of water was used as the reactant with 40% fractional void and5% concentration of the gas, use of 200 curies of Kr-85 gave the dose rate of 2.8×104rad/h at 60°C and 0.9 atm pressure.
Superconductive tunnelling elements have been made with Sn, and the magnetic field dependence of the Josephson current is measured. The surface flatness of Sn film is obtained by lowering as much as possible the substrate temperature at evaporation. To make a stable oxide layer on Sn film surface, reduction of water vapor pressure of oxidizing atmosphere is necessary. When the Josephson current IJ reaches about 20 mA, influence of its own magnetic field on its field dependence becomes apparent, and there occur two new effects, namely, the shifts of magnetic field that makes IJ maximum from H=0 to its two sides-the inclination effect-and the limitation of maximum current to a constant value determined by the material of the element-the self limiting effect. On account of these two effects, the current gain of cross-type elements does not exceed 2 when the magnetic field by IJ affects the value of IJ. Theoretical investigation concerning the frequency-modulation of a. c. super-current by rf field showed the possibility of obtaining the “pure negative resistance” by controlling the phase of rf field.