Vol. 20, No. 12 (1964)
1964-06-20
CONTENT
1964, 20 (12): 1187-1198.
doi: 10.7498/aps.20.1187
Abstract +
Two additional postulates of the eightfold way are suggested on the basis of the analysis of experiments: (1) The nonlinear contribution of the isospin T and the hyper-charge Y to the mass-splitting is independent of the spin-parity of multiplets; (2) In all cases where the octet-singlet mixing takes place, nine particles are grouped into a reducible nine-dimensional representation and are represented by a 3×3 matrix. The trace of this matrix appears neither in the zeroth order term of the mass relation nor in the production and decay interactions of particles. On the basis of these postulates, the classification of the strongly interacting particles, especially the classification of the scalar mesons and the baryon resonances with higher spins, is further discussed. Some predictions are obtained and compared with experiments. The predictions of scalar mesons are discussed in detail and are compatible with experiments. Finally, the results and the implications of the classification are discussed.
1964, 20 (12): 1199-1209.
doi: 10.7498/aps.20.1199
Abstract +
In this paper, the line shapes of the coherent and incoherent output of a three-level (E3>E2>E1) quantum frequency converter have been calculated. The conversion between two optical frequencies, that between an optical and a microwave, and that between two microwaves are discussed. There are two types of operation of the three-level frequency converter. In type I the pumping frequency ～1/?(E2—E1), the frequency of the applied signal ～1/?(E3—E2), and the frequency of the output ～1/?(E3—E1). In type II the pumping frequency ～1/?(E3—E2),the frequency of the applied signal ～1/?(E2—E1), and the frequency of the output ～1/?(E3—E1). It has been shown that for the conversion between two optical frequencies, type Ⅱ is better.
1964, 20 (12): 1210-1215.
doi: 10.7498/aps.20.1210
Abstract +
An approximate expression for the (3.3) partial wave amplitude is given from the analyticity, unitarity, and threshold behaviuor consideration, in which only two parameters, namely the coupling constant and resonance level, are introduced. This expression is in good agreement with the experimental data from the threshold up to the pion laboratory kinetic energy of about 350 MeV. In comparison with Chew-Low's result, it gives the variation of q3/ω ctgδ33 with ω not following a straight line but a curve concave downward. Such an improvement is just required by the experimental data. It is shown, there is some inadequacy concerning analyticity in the Chew-Low's expansion, and this inadequacy has been overcomed in the present formulation.
1964, 20 (12): 1216-1220.
doi: 10.7498/aps.20.1216
Abstract +
The improved Chew-Low expansion, when applied to π-N (3.3) partial wave scattering, has succeeded to fit the experimental data from the threshold up to energies above resonance. Its expression contains only two parameters, namely the coupling constant and resonance level. Therefore, it may conversely determine the coupling constant from the resonance data (level and width) and hence the (3.3) phase shifts. In this paper, we examine the π-Λ P3/2 wave by the same method. At present time the most permissible value of x-A resonance width is 50 MeV, from which we get the π-Λ coupling constant to be g2=34 or f2=0.12. The results corresponding to other possible values of width are also reported. The calculated phase shifts are believed to be legitimate below c.m.s. total energy W≈1450 MeV.
1964, 20 (12): 1235-1243.
doi: 10.7498/aps.20.1235
Abstract +
An approximate wave function ψk(0) is operated on by the operators λ-H and (H-λ)-1, where H is the Hamiltonian operator of the quantum system under consideration. We have shown that, if the resulting function φk is continuous, finite and square integrable in the whole domain of the variables of H, it is a better approximate wave function to the eigenstate ψk of the system than ψk(0) is. The expecting value of H, calculated with φk as wave function approaches to that calculated by the method of second order perturbation with {ψk(0)} as unperturbated states. Polarizabilities of hydrogen-like ions are calculated and good results are obtained.
1964, 20 (12): 1254-1267.
doi: 10.7498/aps.20.1254
Abstract +
Experiments are performed to confirm the chemical etching method for defining the crystallographic orientation of silicon single crystals. The best compositions of the polishing solution for the crystal surface and of the etchant for revealing dislocations are given. The etchant is not sensitive to crystallographic surfaces, and is capable of revealing both edge and screw dislocations, also "new" and "old" dislocations.The following experimental methods are used to verify the correspondence between dislocations and etch pits in the silicon crystals: 1) prolongation of etching time; 2) alternate polishing and etching; 3) etching of matched cleavage faces; 4) observation of dislocations in small-angle tilt boundaries and determination of their geometrical properties; 5) observation and determination of the geometrical arrangement of the etch pit patterns on different crystallographic faces of the specimens under deformation (bending and indentation); 6) checking of the relationship between the radius of curvature and the dislocation density of bent specimens.
1964, 20 (12): 1268-1277.
doi: 10.7498/aps.20.1268
Abstract +
This article describes the difference of mobility between N type indium antimonide ingot and the rectaugular sample, which was cut from the ingot on the position where we want to measure the mobility of ingot. This difference exceeds the error of the measurements. Therefore we think this is due to the introduction of the mechanical damage by cutting and grinding. And at the same time it is also due to the introduction of the thermal damage by the preparation of the electrical contacts. They influence the electrical Properties of the sample studied. From the determination of the change of the electrical properties of the sample one can determine the depth of the mechanical damage thae is about 0.2 to 0.4 mm. From Read's theory of scattering due to dislocation, one can calculate the mobility, and then predict the mobility of the sample. Our experimental results agree with the theoritical prediction quite well. Therefore we believe that the mechanical damage will introduce dislocations (i.e. dislocation crack) into the sample, and they thus influence the electrical properties of the sample. From the experimental results we find the method of preparation of electrical contacts by pressing the gold wire better than that by soldering.
1964, 20 (12): 1278-1283.
doi: 10.7498/aps.20.1278
Abstract +
In this paper we have calculated the binding energies of triton and helium nuclei with a separable nonlocal central potential. The results of calculation show that, with the parameters determined from low energy scattering data, such kind of potentials gives too large binding energies for three and four body systems. Change of the shape of the potential well does not improve the results.
