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Vol. 22, No. 5 (1966)

1966-03-05
CONTENT
ELECTRON SPIN RESONANCE IN PHOSPHORUS-DOPED SILICON
LIN HUNG-I, CHENG JUNG, SHUNG FA-HUA, CHEN CHANG-LAN
1966, 130 (5): 525-532. doi: 10.7498/aps.22.525
Abstract +
In this paper we studied the electron spin resonance in phosphorus-doped silicon, at room temperature and liquid nitrogen, liquid hydrogen temperatures as well as at their temperatures of lower vapour pressure. The concentration for phosphorus impurity is of ~1015—~1018 atom/cm3. A double modulating spectrometer of 3cm band was used.In the experiments, spectral lines for conducting electrons, for surface imperfection centers and for hyperfine structure were observed. The results of experiments also showed the spectral line of interaction between effective electrons and donor nucleus pairs. The g-tactor, the square of the electronic wave function at the donor nucleus,|Ψ(0)|2 , and the electron-nuclear hyperfine interaction constant aD etc., were obtained at 14°K. Our results were approximately in agreement with those obtained by G. Feher at 1.25°K, using electron-nuclear double resonance method.
THE THERMAL DIFFUSE X-RAY SCATTERING AND ELASTIC CONSTANTS OF ZINC
WU TE-CHAN, WANG JEN-HUI
1966, 130 (5): 533-540. doi: 10.7498/aps.22.533
Abstract +
A method of successive approximation to correct the horizontal and vertical divergences of the diffuse X-ray scattering was developed. The elastic constants of zinc calculated from the corrected thermal diffuse scattering intensity are (in dyne/cm2):c11=1.69,c12=0.394,c13=0.549,c33=0.682,c44=0.429,c66=(1/2c11-1/2c12=0.648. They are found to be in good agreement with those obtained from supersonic measurements.
THE FORMATION OF DISLOCATION LOOPS BY VACANCY CONDENSATION
HSIN HSIU-SAN
1966, 130 (5): 541-546. doi: 10.7498/aps.22.541
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The nucleation and growth of dislocation loops and voids in quenched face-centred cubic metals have been studied. Stable nuclei of both may be present, but the growth velocity of dislocation loops is much higher than that of voids, and all the large quenched defects observed by electron microscopy are dislocation loops.
A SIMPLIFIED 180°FOCUSING β RAY SPECTROMETER
MEI J. Y., CHEN H. F., TAN B. L., CHEN J. F., FENG J.
1966, 130 (5): 547-553. doi: 10.7498/aps.22.547
Abstract +
A simplified 180° focusing β ray spectrometer was described. The average radius of the trajectories of the electrons in the spectrometer is 100 mm. The uniform magnetic field of the spectrometer is produced by an electromagnet of single york. With two pole faces as bases, the vaccum chamber has D shape side walls. They are sealed together with rubber gaskets. The radioactive source and the G-M counter can be set along the flat part of the side wall. The magnetic field of the spectrometer is measured by a "zero point magnetometer". Its measuring coil is fixed on a tungsten filament in tension. In order to keep the coil, which is mechanically unbalanced, in a given direction, we must pass a current through the coil, so that the mechanical moment can be counteracted by the moment produced by the interaction between the current in the coil and the magnetic field of the spectrometer. As the mechanical moment is fixed for different magnetic field the current passing through the coil must be varied in order to make the balance.The potentiometric readings of the current can be taken as the measures of the magnetic field. Including the magnetometric measurement, the readings of the spectrometer as a whole have their linearity and precision both at about 0.1%. After a series of rearrangement and improvement, the spectrometer attains its best resolving power for a Hg198 K conversion line with a source of 0.8 mm width. It is 0.7%. For Ba137K conversion line with a source of 2 mm width it attains a resolving power of 0.9%.The essential merit of the spectrometer is its simplicity both in construction and in operation.
POLARIZATION OF PROTONS FROM THE C12(d,p)C13 AND Ca40(d,p)Ca41 GROUND STATE REACTIONS
CHIANG CHENG-LIEH, YU PAN-SHUI, HSIEH TZO, MAO CHEN-LIN, CHEN YEH-HAO, LIANG WEN-HSUEH, WANG CHEN-HSIA, CHENG WAN-HUI, CHAO CHUNG-YAO
1966, 130 (5): 554-568. doi: 10.7498/aps.22.554
Abstract +
The polarization of protons emitted at six angles from the C12(d,p)C13 and Ca40(d,p)Ca41 ground state reactions has been measured. For the C12 reaction, the data at small angles are very close to the results of previous works, and in agreement with thesemiclassical sign rule jn=ln±1/2,P=(±). The value at θ= 115° has not been mea-sured before, we obtained P = 0.529± 0.068 at this angle. For the Ca40 reaction, the sign of polarization which we found in the region of small angles is also in agreement with the semiclassical sign rule, and is the same as those found in the work of Nemetz and of Boschitz, but is opposite to those obtained by Takeda and Bercaw. This difference may be due to the difference in the deuteron energy used, since in these experiments, the three with higher deuteron energies all gave the same positive sign of polarization while the three with lower deuteron energies all gave the same negative sign. After a survey of the polarization data now available we found that the semiclassical sign rule is still true to a certain degree, and that it may be possible to find out a modified sign rule for the use in the nuclear spectroscopy. In some cases, we found that the pattern of the polarization angular distribution is shifted towards small angles as the deuteron energy is increased, and this may be a characteristic of direct reactions. For the correspondence between the cross-section angular distribution and polarization angular distribution, we found that the position of a minimum in the cross-section curve may correspond to the position of a change in sign or of a maximum absolute value in the polarization curve, and that the position of a maximum in the cross-section curve may also correspond to the position of a change in sign in the polarization curve. We discuss these phenomena by using the distored wave theory.
THE STUDY OF TWO-NUCLEON POTENTIAL IN NUCLEI BY MEANS OF INELASTIC SCATTERING
LIU BING-TUNG, HO KUO-CHU
1966, 130 (5): 569-579. doi: 10.7498/aps.22.569
Abstract +
It is proposed that the effective two-nucleon potential in nuclei may be investigated through the direct reaction process in high energy nucleon inelastic scattering. Both DWBA and Glauber's manybody high energy approximation are used in treating the inelastic scattering problem. The effective potential between nucleons within the nucleus has been assumed to have various exchange properties and the spin-orbit term, in the derivation.The differential cross sections and polarization angular distribution for the inelastic scattering of 185 MeV nucleons by C12 with excitation energies 9.6 and 22.3 MeV are calculated. Particle hole model wave functions are used for the nuclear states. All these experimental curves of differential cross section and polarization can be fitted very well with a reasonable set of potential parameters.
THE CONVERGENCE OF A MANY-BODY PERTURBATION SERIES FOR AN ATTRACTIVE FERMI-SYSTEM
TOUR YUNG
1966, 130 (5): 580-588. doi: 10.7498/aps.22.580
Abstract +
The problem of the convergence for Wigner and Schr?dinger perturbation series is discussed by means of the functional analysis method. It is found that the convergent radii of two typic perturbation series are equivalent, but the rates of the convergence or divergence are not equivalent. An useful test is given.
ASSIGNMENTS OF THE BARYON RESONANCES IN S?(12) AND THEIR STRONG-DECAYS
MA CHUNG-CHI, LIU LIAN-SOU, CHEN JI
1966, 130 (5): 589-600. doi: 10.7498/aps.22.589
Abstract +
The assignments of resonances (3/2)-,(1/2)- and (7/2)+ within the multiplets of S?(12) andtheir strong-decays are discussed. It is found that the ((1/2)++0-) decay modes of the (3/2)- particles belonging to the multiplets 16016 and 35100 are forbidden. By redefining the parity of the representations by changing the sign of the massterms in the wave-equations, it is possible to assign the particles ((3/2)-,8) and ((1/2)-,1) in the representation 572. However,the decays of ((3/2)-,1) and (7/2)+ particles through an effective vertex with S?(12) symmetryare still forbidden. The success and failure of S?(l2) in the problem of classification and strong-decays of elementary particles are analysed and discussed in detail.
WEAK INTERACTIONS IN THE SU(6) SYMMETRY THEORY
SONG XING-CHANG
1966, 130 (5): 601-606. doi: 10.7498/aps.22.601
Abstract +
An intermediate boson scheme of weak interactions is proposed within the framework of the SU (6) symmetry theory. Under the assumptions that: (1) the intermediate bosons belong to the IR (irreducible representation) 21; (2) the weak currents belong to the adjoint representation I R 35; and (3) the s- and p-wave semiweak interactions are assigned to the (3*, 1) part of the IR 21 and the (3*, 3) part of the IR 15 respectively, we obtain an effective nonleptonic interaction which gives three sum rules for the s-wave (parity-violating) and one for the p-wave (parity-conserving) decay amplitudes of the hyperons. These relations seem to be well-satisfied by the experimental data.
BRIEF REPORT
1966, 130 (5): 607-610. doi: 10.7498/aps.22.607
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1966, 130 (5): 611-614. doi: 10.7498/aps.22.611
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