Recent works on the slowing down of heavy charged particles in gases and solids are summarized in the view point of stopping power. First, the limitation of the Bethe stopping-power equation in the low energy region is discussed and experimental results for low energy protons and helium ions are reviewed in detail. Next, problems on effective charges of penetrating atoms having atomic number larger than 15 are described. Lastly, after giving typical stopping-power theories in the path-end region of penetrating particles, experimental results are compared with the theoretical predictions.
The moisture balance reported here is specially designed so that the free water-content of snow or ice is obtained by reading the scale on the arm of the balance. The measuring principle is based on the fact that the apparent mass of the snow or ice in water at 0°C is dependent on its moisture-content, The merits of the moisture balance are as follows; 1) only a small quantity of the specimen is necessary. 2) the mass of the specimen is arbitrary. 3) measuring takes only a few minutes.
It is found that the degradation rate of the open-circuit voltage is remarkably larger than that of the short-circuit current in silicon solar cells damaged by 40keV protons. The reduc-tion in the minority carrier lifetime of the diffused layer of a cell thus damaged is estimated by fitting the curve of the observed change in spectral response to the calculated one. Bom-bardment with a total flux of 1.71×1015 protons/cm2 of 40keV protons reduced the n-type diffused region lifetime by a factor of 5 in a particular case. The spectral response change by #2000 Al2O3 lapping on the surface of the silicon solar cell extends to a longer wave length region than that by #4000 Al2O3 lapping in which the degradation of the spectral response is observed mainly in the region of wavelength shorter than 600mμ. This result is due to the decrease of the carrier lifetime in the diffused layer as shown by numerical analysis.
For the purpose of preparing the palladium powders and palladium oxide powders which are both indispensable for the experimental studies on palladium-silver thick film materials, an investigation has been made on the characteristics of the palladium particles and their oxide particles, prepared by chemical reduction with three different processes and by oxidation of the palladium particles thus obtained, by using an electron microscope and X-ray diffraction. The adaptability of these powders for the aimed applications is also discussed. The palladium particles obtained from Pd(OH)2 with HCHO have been found to be thin flakes which are as fine as their crystallite size of 70Å and have a certain catalytic action. The palladium powders having the particle size of 0.05 and 0.3μm are obtained with the other chemical processes. Remarkable crystal growth is observed on the oxide particles when the palladium powders are oxidized at 550°C for 30 minutes in oxygen.
An apparatus has been constructed for measurement of ionic mobilities at a gas pressure of up to about 760 Torr. Ions are produced by alpha particles from 210To inside a drift tube in which. Bradbury-Nielsen type shutter is used. In the measurement of drift time, a digital-analogue converter is used to eliminate the fluctuation caused by the irregurality of shutter pulses. The character of the electrical shutter has been estimated by simple methods and is compared with the experimental results. The performance of the drift tube is examined in laboratory air and the ionic mobility spectrum shows that the positive ions are composed of at least four ion species.