Abstract: Film badges and pocket chambers are now regarded as two essential dosime-ters with which one can estimate the amount of irradiation he has received. Strictly speaking ionization chambers are to be placed in higher rank so far as the principle of measurement of X- or γ-rays is concerned but for practical purpose film badges are preferable in cost and technique when we have a proper badge analyser. In this paper there is reported a research on a new convenient film badge analyser based on a polarisation photometer using a half-shadow method and giving direct reading of dose in milli.roentgen units. Through some preliminary tests on polaroids it is found that “Dichrome” invented by Prof. Y. Hoshino is the only one satisfying conditions required for the present purpose. Designs on the double polaroid and constructions of the instrument can be found in Sect. 4 and in Figs. 3, 4 and 11. The fundamental equation relating true optical density S of a badge film and the balancing angle θ through which an analyser is to be rotated so as to get uniform brightness of the field, is given by _??_ where m is a parameter depending only upon the cutting direction of a polaroid plate. Definitions of two badge scales-Soft and Hard scale (cf. Fig. 16)-are givan in Sect. 8 (1) and (2), and a quality factor a connecting these scales in Sect. 8 (4). An example of badge scales calibrated with Victoreen Survey Meter is sketched in Fig. 17.
Cloven surface of sodium chloride crystals, both rock salt and artificial, was observed by means of X-ray diffraction microscopy (Berg-Barrett method). X-ray patterns by (420) or (440) reflection reveal the sub-grain structure very clearly. In artificial crystals, the dimen-sion of the sub-grains is 0.5_??_5mm and the maximum difference in orientation of sub-grains is 50'. In some specimens there are sub-grains consisting of micro-domains. The size of these micro-domains are several-hundredth mm in diameter. The difference in orientation, if any, among the micro-domains was not detectable within the resolving power of the camera used (2'). In natural rock salt crystals, the dimension of sub-grains and the orientation difference among them are of the same order as in the case of artificial crystals. The micro-domains are not found in natural crystals.
A new formula for computation of the distribution of internal stress in cylindrical glass scaled between two different metals is derived under the same condition as assumed in the derivation of Hull-Poritsky formula which is for single glass-metal seals. When two different metals are given with their known thermal dilatational characteristics, a suitable glass, which, when sealed, exhibits such quality as to withstand uneven sudden excessive heating, is assign-ed by the formula. For verification of the formula, a photoelastic study of the internal stress was made on an experimental product using Babinet Compensator. Agreement with the formula is not as expected, nevertheles, considering the involved technique in making and the assumptions made in the derivation of the formula, the usefulness of the formula is on the whole proved.
An apparatus is described that indicates the resistance of any magnitude from 1 to 106 ohms with maximum accuracy of four figures. The apparatus is essentially a direct current Wheatstone bridge with a variable arm of decade resistance which can be switched by tele-phone selector switches. The unbalance voltage of the bridge is amplified and fed to two thy-ratrons, which energize the stepping magnets of the switches and change the resistance in, either direction to minimize the unbalance. Balancing of the bridge from reset state takes :about 1.5 sec. The apparatus is designed to restore balance automatically as soon as it is destroyed due to change of the resistance. The apparatus may be used-as an analog-to-digital, converter.
Generation of friction tracks on two mutually sliding glass surfaces (a watch-glass and a sheet glass) was observed microscopically. In case the sliding surfaces are virgin, spearhead-shaped friction tracks appear in the apparent contact area when the sliding is'started. These “spear head” tracks are crossed by almost equidistant, <-shaped tiny cracks, and are filled with globular glass flakes which are rather firmly held together. After the slider has travers-ed a considerable distance, or after the surfaces have been rubbed together repeatedly, a quite different kind of tracks appear which are named the “ribbon” tracks. They seem to be smooth under the optical microscope, and are believed to be produced by small glass frag-ments caught between the sliding surfaces.
When a non-glazed ceramic surface is illuminated at an angle of incidence α by a parallel beam, the scattered flux measured with a goniophotometer at an angle of view β is found to be expressed by Lambert's law if its constant is represented by a function of one half of the angle between the illuminator and receptor axes, i.e., (α-β)/2, which is denoted by i. For |i|<75°, the value of this function is proportional, within the error of ±5% (max.), to Fresnel's reflectance with refractive index n=1.6. The experimental procedure is described.