1993 Vol. 17, No. S4

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Study of Multilayer Structures by Synchrotron Radiation with Small Angle Diffraction Method
Wang Jun, Cui Mingqi, Xu Wenxuan, Huang Yuying, Wang Dewu, Liu Jianfei, Xian Dingchang
1993, 17(S4): 311-319.
Small angle diffraction on W/Si multilayer fabricated by magnetron sputtering is carried out at the diffraction station of Beijing Synchrotron Radiation Facility (BSRF). We present the analysis on the periodicity of the multilayer, the thickness of one period and the combination and give a comparison with the fitting result.
The Thin Multiwire Chamber Operating in High Gain Mode and Its Discharge Mechanism
Chen Chang, Li Huantie, Li Xiaoguang, Lü Yusheng, Tang Xiaowei, Tong Guoliang, Wang Jihua, Wu Rongjiu, Yang Kangshu, Zhuang Hongiin
1993, 17(S4): 321-328.
The research results of a thin multiwire chamber operating with strongly quenching gas and its discharge mechanism are presented in this paper. It is indicated by experiments that high gas gain and fast time response can be achieved simultaneously because of operating in the saturated mode. The effect of space charges and the emergence and action of ionizing photons are essential factors in its discharge mechanism, but the latter factor is restrained by the strongly quenching gas.
In the experimental area of particle physics of high energy, the calorimeter plays an increasingly important role. As a part of the work of the L3 International Collaboration, we carried out the research and development of the thin muitiwire chamber operating in high gain mode which is a sort of sampling detector in calorimeter[1,2]. There has been research abroad on this subject[3-6]. In this paper, our research and results are presented.
Transformation Groups in Beam Optics (Part 2): Beam Optical Elements and Systems
Yu Qingchang
1993, 17(S4): 329-333.
On the basis of the research of the transformation groups in beam optics, we discuss problems such as the periodic field focusing, beam matching, chromatic dispersion and aberration.
Study on the Production of tc at LEPII Energy in the Extended Standard Model with Two Higgs-Doublets
Zhang Zhaoxi, Li Xueqian, Yang Maozhi, Wang Jianxiong
1993, 17(S4): 335-345.
In this paper, the production rate of tc (or tc) in the e+e- collision, i.e. e+e-→tc (or tc), is computed in the Standard Model and its extension with two Higgs-doublets and the fourth generation of fermions included. The results show that even the mass of top quark is around 140 GeV/c2, as predicted by the low energy phenomenology, the cross section of this process may still reach an observable value at LEPII, if the favorable parameters are taken in the extension model.
Supersymmetrization of Self-Dual Yang-Mills Theory
Zhao Liu
1993, 17(S4): 347-353.
We give an N=1 supersymmetrization of a four-dimensional seif-dual Yang-Mills theory based on the product superspace (1,1)×(1,1). The model is shown to be equivalent to the zero curvature condition on a superplane parametrized by a point in the complex projective superspace CP3,4. The linear system is given according to this geometrical interpretation, and the effective action which governs the dynamics of the model is also proposed.
The Removability of the Topological Term in the CP1 model and ϑ-Vacuum
Gao Xiaochun, Qian Tiezheng
1993, 17(S4): 355-360.
In this paper, the removability of the topological term in the 1 + ID CP1 model is studied, the unitary transformation which removes the topological term in the CP1 model is obtained. The relation between the topological term to the ϑ-vacuum and geometric phase is then found.
Hamiltonian Reductions of Supersymmetric Self-Dual Yang-Mills Model
Zhao Liu
1993, 17(S4): 361-369.
The Hamiltonian reductions of supersymmef nc self-dual Yang-Mills model are studied. Under the left-right dual constant regular cons:mints, we derive the four-dimensional supersymmetric non-Abelian Toda models, (he corresponding effective action and the associated linear systems. In the special case cf the first order constraints under the principal gradation, we obtain the four-dimensional supersymmetric Toda model. The reduction procedure holds for any Lie sun e-algebra without requiring a purely odd simple root system.
Equivalent Local N-Y Potentials with S=-1 in Quark Cluster Model
Shen Pengnian, Shen Xiaoyan, Zhang Zongye, Yu Youwen
1993, 17(S4): 371-379.
The dynamics of the N-Y system with S=-1 is re-solved, and the spurious resonances in the previous calculation are removed. By performing the double Fourie transformation, the GCM kernels are transformed to the RGM kernels. The equivalent local N-Y potentials for S=-1 systems are then calculated. It is shown that the obtained potentials are similar to Yamamoto's results obtained by using the OBE model where the phenomenological hard cores were adopted. With these potentials, the phase shifts and cross sections for S=-1 systems can be re-produced.
A Simple Two-Band Mixing Model of Superdeformed Bands
Xing Zheng, Wang Yangii, Chen Xingqu
1993, 17(S4): 381-387.
Anomalous behavior of the dynamic moments of inertia is interpreted for the two SD bands (193Hg(b1) and 193Hg(b4)) in the A ~190 region in terms of a parametrized two-band mixing model. The calculations predict that the dynamic moments of inertia J(2) will start to decrease at about hw ≈ 0.42 MeV for 194Hg(b1).
Effective Boson Numbers and Their Applications
Zhao Yumin, Gu Jinnan
1993, 17(S4): 389-394.
A method for obtaining effective boson numbers is reviewed briefly, and the evidence for the existence of the saturation phenomenon of effective boson numbers is collected. With the effective boson numbers presented by a semi-empirical method, formulas of the intrinsic quadrupole Q0 as a function of (NπeffNveff) for even-even nuclei with A ≥ 70 are presented, and calculations are performed for nuclei 142Ce and 144Nd numerically. These results are satisfactory.
Branching Rules for U(N)⊃SP(N)⊃O(3)
Wang Jiajun, Sun Hongzhou
1993, 17(S4): 395-402.
Branching rules for group chain N(U)⊃SP(N)⊃O(3) of the irreducible representations[2a1b] of U(N) are discussed by formulas of group direct product decomposition. Simple recurrence formulas of these branching rules are obtained. It provides a simple method to find the branching rules for this type of problem. They are very efficient to simplify the calculations of Fractional Parentage Coefficients. This method can also be used in finding branching rules for group chain U(N)⊃O(N)⊃0(3).
The K++ Ratio in High-Energy Nucleus Collisions and the Effect of Secondary Collisions
Liu Bo, Jiang Huanqing
1993, 17(S4): 403-409.
We calculate the effect of secondary collisions to the K++ ratio by the eikonal approximation and find that the secondary collisions are important.
Particle-Number Conserving Calculation of the Bandhead Moments of Inertia of Identical SD Bands
Jin Taihao, Zhao Zhengji, Zeng Jinyan
1993, 17(S4): 411-421.
Using the particle-number conserving (PNC) method for treating the cranked shell model, the bandhead moments of inertia of the superdeformed (SD) bands 192Hg and 194Hg(l,2,3) were calculated. The configuration structures of the SD bands near the bandheads and the mechanism of the variation of bandhead moments of inertia with the pairing interaction strength G were investigated. The analysis shows that:
(1) the difference between the bandhead moments of inertia, δJ0, is sensitive to the pairing interaction strength, but insensitive to the Nilsson parameters κ, μ and the deformation;
(2) in the A~190 region, the pairing interaction still plays an important role and the δJ0 is mainly attributed to the blocking effect;
(3) the pairing interaction strength in the SD nuclei seems much weaker than in normally deformed nuclei.