1989 Vol. 13, No. S2

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The Escape Gating Technique for a Multiwire Proportional Chamber
Shen Changquan, Shen Peiruo, Ye Zongnan, Li Xiaonan
1989, 13(S2): 115-124.
A balloon-borne spectrometer for hard X-ray astronomy observation in space has been developed with the escape gating technique. It contains a multiwire proportional chamber filled with high pressure mixture of xenon and methane. In this paper, we will describe the principle of the escape gating technique, the way to realize it in our spectrometer and its practical performance. The spectrometer was set in a balloon and successfully launched to an altitude of 37 km above sea level near Beijing on August 31, 1986. Useful observing data were recorded during the flight.
Interpretation of Azimuthal Anisotropical Gamma-Family Events
He Yudong, Zhu Qingqi, Huo Anxiang
1989, 13(S2): 125-130.
The azimuthal anisotropy of gamma-family events obtained by mountain emulsion chambers is studied. By using the D-ND and SD-SH models, the gamma-family phenomena are simulated with the anisotropical events with adequate frequency reproduced. The study indicates that the few-particle diffractive production in the fragmentation region mainly accounts for the azimuthal anisotropical events. The QCD jet production is considerably insignificant to the anisotropical effect.
Analysing Depth Profile of Hydrogen in Materals by Elastic Recoil Detection
Liu Shijie, Wu Yue, Sheng Kanglong, Li Chunying
1989, 13(S2): 131-138.
The elastic recoil detection (ERD) by using a 2.0-2.5 MeV 4He ion beam has been performed to detect the depth profile of hydrogen in the silicon oxide and silicon nitride films. The correlation between the hydrogen content and deposition condition is given. Maximum probing depth, detection limit and depth resolution are discussed under our experiment conditions.
The Angular Distribution of Photons in Orthopositronium Decay into Three Photons
Yang Baozhong, Tan Yong, Tang Xiaowei, Bian Zuhe
1989, 13(S2): 139-142.
The three-photon decay of positronium is studied by using a positronium source, composed of 22Na and silica aerogel and the triple fast coincidence method. The angular distribution of the photons in the large angle region is measured under symmetrical configuration of two photons with respect to the third photon in the final state. Combining with the data in the small angle region which has been published before, the complete curve of the angular distribution of photons is obtained. The experimental results are in good agreement with the theoretical predicted values.
Electron Clouds in Axial Symmetrical Space-Charge Lenses
Yu Qingchang
1989, 13(S2): 143-148.
The focusing properties of a space-charge lens depend on the size, shape and density distribution of its electron cloud. In this paper these parameters are discussed based on both numerical and analytical methods.
Spline Function Representation For Transformation of Beam Phase Space With Arbitrary Contours
Mao Naifeng, Li Zenghai
1989, 13(S2): 149-156.
In order to study the transport of beams with arbitrary phase space contours, the spline function representation of the phase space contours is proposed in this paper. Having fitted the phase space contours with cubic spline functions, the phase space transformation is reduced to the spline function transformationj and the beam envelopes can be expressed with spline functions. The corresponding computer program is written and some typical examples are presented to illustrate the usefulness of this method.
Vacuum State of 2+1 Dimensional SU(2) Lattice Gauge Theory With Fermions and Spontaneous Chiral Symmetry Breaking
Luo Xiangqian, Chen Qizhou, Guo Shuohong
1989, 13(S2): 157-164.
The vacuum structure of 2 + 1 dimensional SU(2) LGT with fermions is studied by incorporating the exact ground state of pure gauge theory and the variational fermion vacuum state. We have calculated the fermion condensation <ψψ>, and obtained an improved scaling behavior.
Study of Collective Spectrum for 157,159Tb and 155,157Gd
Liu Yong, Sang Jianping
1989, 13(S2): 165-174.
A microscopic approach for studying collective states of odd-mass nuclei is proposed in terms of the interacting boson-fermion model. The model Hamiltonian is derived and used for calculating the spectrum of 157,159Tb and 155,157Gd isotopes. As a result, qualitative agreement between the numerical results and the experimental data is obtained.
The Effective Two-Meson-Exchange Potential Derived From the Quark-Antiquark Pair Creation Model
Yu Youwen, Shen Pengnian
1989, 13(S2): 175-180.
The effective two-meson-exchange potential with regard to the box diagram in the N-N interaction has been derived by virtue of the one-gluon-exchange quark-antiquark pair creation model. The result shows that the general feature of this effective potential agrees with that of the phenomenological σ-meson exchange potential in the coordinate space.
The Ɩ/E Puzzle and the Moment Analysis
Yu Hong
1989, 13(S2): 181-184.
We introduce the photon angular distribution for the moment of the process e+e-J/ψ→γB, B→P1P2P3 to discuss the (Ɩ/E puzzle. It provides a criterion to distinguish the 0-+ state from the 1++ state in the process e+e-→J/ψ→γKKπ.
A Model of Four Dimensional Heterotic String
Gong Shangqing, Qu Lihu, Yu Shonmian
1989, 13(S2): 185-192.
We constructed a new model of D=4 heterotic string with the gauge group[SU(2)]6, which consists of the right-movers of the D=4 fermionic string and the left-movers of the D=10 N-S bosonic string. The massless ground state of the string contains the 4 dimensional supergravity multiplet and the super-Yang-Mills gauge field multiplet. The new model is tachyon-free, Lorentz invariant and supersymmetric.
Microscopic Analysis of the Low-Lying Even Parity Bands in 168Er
Huang Haixin, Wu Chongshi, Zeng Jinyan
1989, 13(S2): 193-206.
Taking into account the pairing plus quadrupole-quadrupole interaction, the intrinsic properties of the low-lying bands (even parity) and the related E2 transition probabilities in 168Er were calculated in the frame of Bohr-Mottelson-Nilsson model. The agreement between the calculated and the observed results is satisfactory. Some difficulties encountered in the IBM prediction do not appear in the present calculation.
Calculation of the Effective Moment of Inertia of Fissioning Nuclei at the Saddle Point
Chen Xinyi, Hu Jimin
1989, 13(S2): 207-212.
The effective moment of inertia, charge density distributions of the fissioning nucleus 170Yb and 254Fm at the saddle point are calculated by using the continuous medium model with variable densities.
Rotational Effect on Electromagnetic Transitions in Nuclei
Xing Zheng, Chen Zingqu
1989, 13(S2): 213-219.
The signature-splitting of the energies, B(M1)-values and dynamical quadrupole moment in 159Tm are investigated by means of the extended particle-rotor model. In particular, the effect of second-order Coriolis interaction on the signature-dependence of B(M1)-vaIues is discussed. It was noted that the calculated values are in qualitative agreement with the measured data.