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Vol. 22, No. 2 (1966)

1966-01-20
CONTENT
THE PAIRING EFFECTS OF NUCLEI ON THE ANGULAR DISTRIBUTION OF THE FISSION FRAGMENTS
ZHUO YI-ZHONG, LI ZE-QING, LI MING-SHOU
1966, 127 (2): 136-145. doi: 10.7498/aps.22.136
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The derivation of the moment of inertia for the ground state nucleus given by Migdal in the quasi-classical approximation has been extended to the excited state case, i.e. T≠0. We have calculated K02 , the parameter of the angular distribution of the fission fragments. The results arc compared with the experimental data. This shows that under the present approximation the "anomalously" small K02 of fissioning nuclei in the uranium region at low excitation energy (Eexc≤15 MeV) can be explained by introduction of the pairing effects in nuclei. Furthermore, the absence of the "anomalous" phenomena for fissioning nuclei near the lead region may be qualitatively interpreted by means of the dependence of pairing effects on angular momentum.
HYPERON PAIR ANNIHILATION OF pp AND SU(3) SYMMETRY
LIU LIAN-SHOU
1966, 127 (2): 146-151. doi: 10.7498/aps.22.146
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In this work the hyperon pair annihilation of pp is treated by means of the pole approximation and a broken SU(3) symmetry. There are two sources of symmetry breaking: (1) mass differences, (2) at each vertex there is a factor inversely proportional to the meson mass. The calculated angular distribution and branching ratio fit the experimental data.
ON THE ISOTOPIC VECTOR ELECTRIC AND MAGNETIC FORM FACTORS OF THE NUCLEONS
CAO CHANG-QI, ZHU YUNG-LUN, WANG SU-SEN
1966, 127 (2): 152-162. doi: 10.7498/aps.22.152
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In reference to a theorem proved by Sugawara and Kanazawa together with recent studies of asymptotic behaviour by Omnes, the subtration in the dispersion relations of Gi(t) and Гi(t) is discussed. The contributions to the Гi(t) and Fπ(t) by the "far away" singularities are accounted for more carefully; the results so obtained seem to agree pretty well with both the electric and magnetic isotopic vector form factors; the Гi(t) satisfies the requirement proposed by Vick from the analysis of π-N scattering data. Our calculation also shows that the total isotopic vector charge and magnetic moment are mainly due to the 2π intermediate state contribution; it is very probable that there exist no core point charge and magnetic moment at all.
THE GROUP SU4 AND SYMMETRY OF THE ELEMENTARY PARTICLES
YEH PENG-SHENG
1966, 127 (2): 163-173. doi: 10.7498/aps.22.163
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In this paper, using the general theory of the Lie groups we concretely discussed the mathematical treatments of the group SU4. The algebra structure of the group SU4, the formula for the dimensions of the irreducible representation, the explicit form of the three elementary representations, and the reduction of direct products of representations arc given. The following symmetry models of the elementary particles based on the group SU4 are built: (1) the model of Baery-Van Hove, (2) the model of Schwinger, (3) the model of Sakata with particle and anti-particle symmetry, (4) the octet model with particle and anti-particle symmetry. In these models some new consequences consistent with the experiments are obtained.
PULSED ELECTRODELESS DISCHARGE AS A LIGHT SOURCE FOR LASER EXCITATION AND OBSERVATION OF THE CHARACTERISTICS OF LASER OUTPUT
CHANG ZUNG-KUI, YEH MOW-FOH
1966, 127 (2): 174-182. doi: 10.7498/aps.22.174
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High voltage pulsed electrodeless discharge in rare gases can be used as a light source for laser excitation. In this paper, some initial experimental results in this respect are reported. In the first part of the paper, the light source and its light output measurements are described. The second part is concerned with some investigations of ruby and Nd-doped glass lasers, pumped with electrodeless discharge tubes. These investigations contain determination of thresholds, observation of spikes, oscillation on single mode, and regular damped oscillation.Finally, the possibilities of further development are discussed.
SPIN-LATTICE RELAXATION AND CONCENTRATION EFFECTS OF Cr3+ IN RUBY
LIU DA-JAHN, CHEN GIAO-FONG
1966, 127 (2): 183-187. doi: 10.7498/aps.22.183
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The experimental technique and results from measuring spin-lattice relaxation times by the pulse saturation method at X band are described. Double frequency is used to synchronize the oscilloscope in order to measure T1 more precisely. The spin lattice relaxation times of Cr3+ in ruby have been measured for several different concentrations. It is concluded that T1 of various transitions are nearly the same, but become shorter apparently with increasing Cr3+ concentration.
ELECTRONIC SPONTANEOUS POLARIZATION OF O-2 IN THE ABO3-TYPE CRYSTALS
LEE JING-DER
1966, 127 (2): 188-196. doi: 10.7498/aps.22.188
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The crystal fields lower the 3s3d0 electronic energy level of O-2 and make it hybrid with the 2pπ level at transition temperature to give a spontaneous polarization orbit according to the Jahn-Teller effect. In various polarized phases, the direction of each polarization orbit of three oxygens in unit cell was determined by the covalent bonds of BO6 octahedron. A correct ratio of the componeons of Ps in four phases of BaTiO3, and the screen constant which agrees with Slater's value for O-2 were given. For cubic to tetragonal transition, the theory was compared with Devonshire's theory.
DETERMINATIONS OF THE SYMMETRIES OF SINGLE-ELECTRONIC LEVELS AND PHONONS IN A CRYSTAL
WANG GUO-VEN
1966, 127 (2): 197-204. doi: 10.7498/aps.22.197
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In this paper, the formulas for convenient determinations of the symmetries of single-electronic levels and phonons in a crystal are obtained, and the simple methods based on these formulas are described through applications to some examples.
THE NOISE OF THE p-TYPE INDIUM ANTIMONIDE
WU TZU-CHIANG, TANG TING-YUAN
1966, 127 (2): 205-213. doi: 10.7498/aps.22.205
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The noise power spectrum of a few high purity p-type InSb has been measured at 77°K. In general, it consists of the generation-recombination noise and the modulation noise. The magnitude of the former is proportional to p0-2, while the latter is proportional to p0-1, where p0 is the equilibrium concentration of the majority carriers. The purer the sample is, the more important is the generation-recombination noise. The magnitude and the power spectrum of the G-R noise are in accord with the present theory. The lifetime τ of the majority carriers can be obtained from the G-R noise power spectrum; it is found that τp0 = 1.1×109sec/cm3.
THE CHANGE OF THE ELASTIC CONSTANTS OF CRYSTALS DUE TO VACANCIES
WANG YUNG-CHIANG
1966, 127 (2): 214-222. doi: 10.7498/aps.22.214
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Consider the crystal containing a small fraction of vacancies as a homogeneous crystal, and the difference between perfect and imperfect crystal reduces to the modification of the potential function. The relation between the rate of change of the elastic constants, c11 and c12, and concentration of vacancies is derived by the use of a Morse function. Owing to the relaxations of the neighbouring atoms, the effect of the elastic constants on the change of mutual interactions due to vacancy relaxation is taken into account. The first and second nearest-neighbour relaxations for Al are found to be (1.61, -0.32), expressed in percentage of normal distances. The positive sign indicates relaxation toward the vacancy and the negative sign indicates relaxation away from the vacancy. In the case of Cu, it is estimated that 1 per cent vacancy concentration would decrease the elastic constants by 1.3-1.4 per cent. However, the vacancy would have less effect on the elastic constants in Al than in Cu.
THE PERTURBATION THEORY FOR THE FIRST-ORDER APPROXIMATION OF THE DIFFRACTION PROBLEMS
CHENG LU
1966, 127 (2): 223-232. doi: 10.7498/aps.22.223
Abstract +
Applying the perturbation theory to Helmholtz's equations of spherical and sphero-conal systems of coordinates, the author deduces the expressions for the perturbation terms of diffraction due to a plane angular sector with its angle nearly equal to π and those due to an elliptic cone with θ nearly equal to π/2 respectively. Then, following the principle in [10], substituting the diffracting plane disk of arbitrary form by its inscribed polygonal disk and the diffracting surface of arbitrary form by a surface which consists of many small inscribed elliptic cones of the original surface, we make the summations of the perturbation terms for the sectors of the polygon and those of the tops of the small cones respectively. In the limiting case these two summations become integrals, hence the diffraction fields of first-order due to the disk (thereof, the complementary plane screen with a hole) and the surface of arbitrary forms are derived respectively.
1966, 127 (2): 233-244. doi: 10.7498/aps.22.233
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BRIEF REPORT
1966, 127 (2): 245-249. doi: 10.7498/aps.22.245
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1966, 127 (2): 250-252. doi: 10.7498/aps.22.250
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1966, 127 (2): 253-256. doi: 10.7498/aps.22.253
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