Inducement of color to optical glass by irradiation is used to measure neutron exposure dose from total exposure dose of gamma-rays and neutrons emitted from Ra-Be source by determining first the shade of induced color by gamma-ray irradiation alone. Two kinds of optical glass, borosilicate crown glass (BK-7) and flint glass (F-2), are used. A linear relation is found between neutron exposure dose and shade of the induced color. BK-7 glass can be used for measuring higher dose than F-2 glass.
Radiation relays are widely used for process control in factory production; they are used also in railway traffic signalling systems. There are two types of radiation relays. The one is cons-tantly in operation at low counting rates and gives signal on arrival of pulse of high counting rates; the operation of the other is the reverse. The former type is dealt with in this paper. It is very important that such insutruments should be highly reliable and “Fail-Safe”. A pulse width jamming circuit has been devised. Every incoming radiation pulse is shaped to a uniform wide rectangular wave form by an electronic circuit. These shaped pulses are power amplified with transformer coupled A. C. amplifier and, after rectification, utilized as a relay power supply. At high counting rates, overlapping of pulses deprives the rectification of its effect, hence no power to operate the relay, establishing the pulse width jamming. As the generated power is made strong enough to operate the relay, energization of the relay at low counting rates is the evidence of normal working of the whole system. Thus, the conti-nuous Self-Checking action becomes possible. Any failure in any part of the circuit fails to deliver real pulses or gives spurious high rate pulses, rendering the power to relay to vanish. Thus, Fail-Safe action is achieved. Another type, the coincidence counting type, of radiation relay is outlined.
A 6MeV electron linear accelerator was installed in Nagoya Government Industrial Research Institute. Its dynamic characteristics are experimentally studied. The principal conditions for determining the beam energy of accelerated electrons are found to be the microwave power, the microwave frequency and the electron current emitted from the gun fillament, the interrelations of which are shown on a synthetic operation chart which also shows the region where the pulse shortening effect does not appear.
Electrostatic charge may be produced in glass tubes by flowing liquid. Effect of gamma-radiation on such charge is investigated with exposure dose rate 348r/hr, total doses 87.0×102, 28.18×102, 56.03×102 and 83.87×102 roentgen at room temperature. The results show that the amount of produced electrostatic charge becomes smaller when the exposure dose exceeds a certain value. Therefore, irradiation is considered useful for preventing the electrification of glass tubes by flowing liquid.
Ionizing radiations produce visible color center in glass which contains multiple ions. The color induced to manganese glass by gamma-ray irradiation, natural fading of the induced color, and effects of factors-ultraviolet and visible rays of light, heat, and D. C. electric tension-on quickening of fading of the color are investigated. Observed result is that, the induced color at 430mμ is not affected either by the above factors or by gamma-ray dose rate. Therefore, manganese glass can be applied to dosimetry in the range of 3.5×104 to 107 roentgen with sufficient color stability.
Nuclear magnetic resonance absorption of stretched Teflon is studied. The second moment of stretched Teflon is calculated on the assumption of all the molecular chains being rotating around the axes of their main chains at room temperature and by the use of the distribution of crystallites determined from experimental results. Calculated result agrees with experimental result, and rotational transition of this polymer at about room temperature is verified. Molecular structure in rigid state and molecular motions at other temperatures are briefly discussed.
Wire-covered cathodes have been prepared by winding Ni, Mo, Pt or W wire on usual oxide coated cathodes, and their thermoionic properties, thermal evaporation, and increase of evaporation by electron bombardment are measured. Pulse emission of these cathodes varies from one tenth of that of bare cathodes to that of L-cathodes in varying the coverage from 50% to 100%. When compared with bare cathodes, amount of free Ba in evaporant from wire-covered cathodes is increased owing to the reduction of oxides by the wire and contained impurities, if any, in the wire, but the increase of evaporation by electron bombardment is much smaller from wire-covered cathodes than from bare cathodes. Therefore, wire-covered cathodes are suited to tubes, the cathode of which is subjected to electron bombardment.
Russel method of measuring the total radiation from furnace ports and domestic appliances has two merits. One is that the use of a semi-circular arc, which is made to rotate about the vertical diameter as axis and the source of radiant heat as center and on which a radiometer is mounted, facilitates the measurement. The other is that the measuring points are so chosen that the total radiation is obtained by a simple summation of all the measured values which are of equal weights. Russel method is afterall a practical one; its measuring error can be tolerated when compared with the mathematical method of integrating the curve of radiant flux distribution. The error, however, will become smaller and eventually converge to zero if the measurement is made at a. large number of points. This paper deals with this convergency of calculater error when the distribution of radiant heat obeys the Lambert cosine law and shows that the revised Russel method, in which the horizontal line normal to the vertical axis at the center in meridian plane is taken as the axis of rotation and the concept of intensity mean is introduced instead of area mean, is equal in result to Russel method.