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Vol. 8, No. 3 (1951)

1951-02-05
Topics
CONTENT
INVESTIGATION ON HEAVY NUCLEI BY PHOTOGRAPHIC METHOD
HOANG TCHANG-FONG
1951, 18 (3): 183-194. doi: 10.7498/aps.8.183
Abstract +
An improved δ-ray method for determining the nature of heavy nudei is obtaincl img application of a seini-empirical formula giing;; the δ-ray density per 100 μ of the track in function of the remaining range R; N=C ZpR-b with p=1.54. b=0.46 and C depending on the nature of the emulsion and the conditions of measurement.Discussions arc given on the "thin-down effect" and the relation between the ihin-down length and the atomic charge.
THE F-2 REGION OF THE IONOSPHERE AT WUCHANG DURING THE SOLAR ECLIPSE OF MAY 9, 1948
C. T. KWEI, P. H. LIANG, J. H. MOH, W. CHOW
1951, 18 (3): 195-206. doi: 10.7498/aps.8.195
Abstract +
From data obtained during the eclipse and on control days, the effective coefficient of recombination for F-2 layer is found to be 4×10-10 cm3/electron per sec. The magnitude of a is apparently a function of the height of the layer which becomes lower with increasing latitude. Solar eruptions may be associated with two of the discontinuities of the eclipse curve. The thickness of the F-2 layer became compressed and dropped as a whole during the eclipse, possibly due to air movement caused by lowering of temperature. The sporadic E layer was not influenced by the change of solar radiation, and must be due to other causes.
DEVIATION OF VAN DER WAALS INTERACTION FROM ADDITIVE RELATIONS
KUN HUANG, AVRIL RHYS
1951, 18 (3): 207-221. doi: 10.7498/aps.8.207
Abstract +
With a lattice of isotropic point-oscillators as an idealized model, the error of the usual additive approximation for the van der Waals interaction in solids is estimated. For a few common crystals, the estimated errors for van der Waals energy and its first and second derivatives have values up to 13%, 34% and 70% respectively. The model moreover points to the possible importance of the long range dipolar interaction as a mechanism determining the structure of the exciton-band in. insulators.
ROTATIONAL MAGNETIZATION IN POLYCRYSTALLINE FERROMAGNETICS
S. T. PAN
1951, 18 (3): 222-234. doi: 10.7498/aps.8.222
Abstract +
In the attempts to derive from theory the magnetization curve, in the region of rotational magnetization, for well annealed ferromagnetic polycrystals, a generally recognized complication is the possible existence of internal fields caused by the out of alignment of the magnetization vectors of the grains. However, if such internal fields do not really exist, a simple deduction by the usual formal treatment predicts that the magnetization curves of polycrystals, of the same crystalline structure and having the same sign for the values of the principal anisotropy constant, can be brought into coincidence by expressing the intensity of magnetization and the field in proper reduced units'. This prediction is checked experimentally by measurements on iron and an iron alloy containing 15 percent cobalt by weight. In each case, it is found that the normal magnetization curves for various temperatures can be brought into coincidence in the manner as indicated. It is therefore concluded that the effect of internal fields on the process of magnetization in the case of polycrystals cannot be any greater than that in the case of single crystals. The absence of wide spread internal fields of magnetic origin in polycrystals during rotational magnetization is then discussed in the light of recent developments in the domain theory.
NOTE ON VELOCITY TRANSFORMATIONS IN SPECIAL RELATIVITY.
HSIN P. SOH
1951, 18 (3): 235-238. doi: 10.7498/aps.8.235
Abstract +
Three dimensional velocity transformations in special relativity can form quaternion group if each is subject to a further rotation about the direction of the velocity through the same imaginary angle.
ON THE TRANSFORMATION CONNECTING TWO SYSTEMS IN RELATIVE ACCELERATION
MU-HSIEN WANG
1951, 18 (3): 239-244. doi: 10.7498/aps.8.239
Abstract +
In previous papers,1 we have obtained, for a special case, the transformation coefficients connecting two systems in relative acceleration and have shown that the transformation is the only possible one that gives electromagnetic fields the observed values and is integrable. In the present paper, we will give the general co-ordinate transformation connecting two systems in arbitrary motion and its application to obtain the general electromagnetic fields due to a charged particle in arbitrary motion.
A PHOTO-ELECTRONIC FOG COUNTER
Y. T. WEI
1951, 18 (3): 245-258. doi: 10.7498/aps.8.245
Abstract +
A photo-electronic fog counter has been developed on the principle of counting flashes of light scattered from individual fog droplets with a photomultiplier. Since a photomultiplier appears to act very rapidly and reponse in a time of the order of 10-8 sec. is possible, the maximum counting rate is limited only by the sealer which is associated with the counter. If a Berkeley Sealer (Model 1000B) is used, this counter is capable of counting fog droplets at a rate of 300,000/min. with very small error and the chance of coincidence countings is therefore small. This counter will prove useful for even very dense fogs or any other kind of aerosols. The optical theory of scattering which may lead to the determination of particle size from size of electric pulse has been introduced.Preliminary experiments show the applicability of this counter for droplet size measurement. There seems to be of no doubt that this counter could register the smallest droplets that occur in natural fogs (i.e., of the order of r≈1 micron) and a better sensitivity can be achieved by reducing stray-light noise level and improving signal to noise ratio. Possibilities of further improvements of the present instrument both as a fog counter and as a droplet size indicator have been discussed.
ON THE THEORY OF BETA-DISINTEGRATION
NING HU, MIN YU
1951, 18 (3): 260-269. doi: 10.7498/aps.8.260
Abstract +
It is pointed out that the divergence in Yukawa's theory of βdisintegration can be removed by charge and mass renormalizations, whereas in conventional Fermi's theory this is not the case. From the known interaction constants for nuclear β-decay, for μ-e decay and for the interaction of μ-mesons with nucleons, it is found that the life time of the intermediary meson should be of the order 10-16 sec. We can therefore consider this intermediary meson as a new particle which has not been observed experimentally owing to its extremely short life time. Best agreement with experiment is obtained if the intermdiary meson is pseudo-vector in nature and under pseudo-vector interaction with the Fermi fields, those types of interactions being excluded which lead to divergent results for observable effects.