The total time-lag τ necessary for building up strong continuous spectral emission after a flash tube is triggered consists of the time-lag τi in the discharge current and the delay-time τl in the light emission after the discharge is started, that is, τ=τi+τl. Both the values of τi and τl increase with increase of the gas pressure p and the electrode distance d, and decrease with the increase of the voltage V applied to the main electrodes. In this study, the value of τi and its fluctuation have been determined by varying the triggering intensity for flash tubes filled with various rare gases. It is made clear that τi tends to approach a certain definite value characterized by p, d, V and the nature of gas and that the fluctuations become smaller with the increase of the triggering intensity. When a flash tube is used as the light source in high-speed photography, it is pointed out that the triggering intensity should be chosen correctly according to the discharge conditions such as p, d, V and the nature of gas. The experimental results of τi have been analyzed qualitatively on the assumption that the discharge in a flash tube may be looked upon as a simple Townsend discharge.
A study is made to determine algebraically the shape of a thin achromatic doublet (cemented) of focal length ƒ' with a stop set behind it, corrected for astigmatism in the Seidel region for the object plane placed at various distances from the doublet. Algebraic equations derived from Zinker-Sommer's anastigmatic condition for an achromatic lens are always quadratic in terms of the refractive power of the first component, the form of the curves representing the quadratic equations depending on the choice of the first and second lens materials. These equations have two solutions or none, which restricts the doublet to be of required specification. The result of theoretical treatment can readily be applied to magnifying lenses.
A self-recording spectroradiometer covering the wavelength range of 350mμ_??_2500mμ has been devised for the study of plant growth in artificially illuminated laboratory and in open air. This spectroradiometer consists of a radiation receiving head which is made to move freely in all directions, an amplifier, a rectifier, a meter or recorder and a stabilized source of radiant energy which is a standard tungsten filament lamp. The radiation receiving head has a light scattering frosted quartz plate, neutral gray filters for incident light intensity attenuation, interference filters, an infrared filter, a chopper, a detector (photomultiplier for visible region and PbS photoconductive cell for near infrared region), and a chopper driving synchronous motor. Wavelength scanning is carried out by turning a disc on which the filters are mounted. The calibration of the meter is by measuring the energy of radiation in each of the filtered ranges impinging on the frosted quartz plate. Spectral energy distributions obtained on various kinds of fluorescent lamps and mercury lamps agreed fairly well with Azuma's data.
Characteristics of metal light pipes were measured in the spectral range from 20 to 110μ with a far infrared spectrometer. The transmission of the far infrared radiation through light pipes gradually decreases as the length of the pipe increases. The transmitted energy through fairly long pipes is found to be sufficient for measurements. The transmission of the far infrared radiation through a gap between disjoined pipes is fairly high. The energy distribution of radiation in the pipe is determined by measuring the transmission of radiation through a holed plate inserted in the pipe. The energy density is higher on the axis of the pipe than near the pipe wall. The value of the transmission of samples obtained in light pipes coincides well with that obtained in ordinary measurements.
Most powdered substances possess some flow properties such as creep and dilatancy when loaded. In this work, mechanical properties of various powdered food are examined by the use of a modified parallel plate plastmeter. Logarithmic plots of vertical strain vs. loading time become linear from about 30 sec. after loading. This linearity is independent of the load, and its slope varies with the particle size and absorbed moisture. A linearity is also found in the relation of vertical strain vs. shearing stress on logarithmic scales. By the application of Nutting's equation γ=φ-1σβtκ where γ is the strain, σ the stress, t the loading time and φ a material constant, the “firmness”, φ, β and κ, which signify the property of powdered substances, are obtained from the slopes of linear portions of the above two relations. Logarithmic φ, β, ane κ were found varying in ranges 6.0_??_8.0, 0.2_??_2.0 and 0.2_??_0.3 respectively. These variations are considered ascribable to differences in particle size, fineness of particle surface structure and absorbed moisture.
Amount of content and distribution of oxygen in silicon crystals grown by pulling-up from silica crucible are studeid by infrared absorption technique to elucidate the intermixing mechanism of oxygen. By varying the pulling-up condition, the following results are obtained. 1) Oxygen density in silicon increases with increasing speed of rotation of the crystal during growth. 2) Slender crystals pulled-up from a large crucible have a small oxygen content. 3) Distribution of oxygen along the pulling direction is similar to that found when other im-purities of the segregation constant of smaller than unity are intermixed. 4) Distribution of oxygen, lateral to the pulling direction, is nearly uniform. The above shows that the oxygen comes into the crystal by agitation of silicon melt caused by convection and rotation of the crystal during growth rather than diffusion from crucible walls. Some of the above results were already reported by Hrostowski et al. In the present work, the intermixing mechanism of oxygen, the relation of oxygen distribution to crystal form, and the way the oxygen content increases in the crystal are dealt with.
An experimental study has been carried out on photoconductivity and photoluminescence of sintered layer of silver-activated cadmium sulphide. The sintered layers were prepared in varying amounts of silver concentration from zero to ten gram atom per cent. The photoconductivity of CdS: Ag is shown by one band with a maximum at 5400Å. This is explained by the formation of hole traps about 0.15 eV above the valence band. The photoluminescence at low temperatures gives two bands with maxima at 6200Å and 7300 Å. The 6200Å emission is found only at low Ag concentration, while, the 7300 Å emission is observable further at higher temperature and Ag concentration. The relation between photoconductivity and luminescence is discussed and the mechanism of luminescence is explained.
It is shown that when packed powdered food is mechanically tapped, the relation between the strain γ and the number of consecutive tapping N is represented by an equation γ=abN/(1+bN) where a and b are the volume decrement from initial to final volume and the fluidity of the powder respectively. The value of a ranges from 0.9×10-1 to 3.3×10-1 and that of b from 2.3×10-2 to 17.5×10-2. a-value is varied with the magnitude of tapping impact; for whole milk powder, which is cohesive, it becomes constant above a certain magnitude of impact, however, for skimmed milk powder, which is not cohesive, it rises proportionally to the square of the magnitude of impact and becomes maximum at about the magnitude at which a-value of whole milk begins to become constant. Such is the case in which the separation phenomenon of tight packed powder occurs, a-value of skimmed milk powder decreases with increasing moisture content; at about 8% of the content, the fluidity becomes maximum owing to α transition of lactose in skimmed milk powder particles.