1991 Vol. 15, No. S1

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A Study of Super High Energy γ-Family Events Through Large-Scale Fe Emulsion Chambers
Ren Jingru, Lu Suiling, Su Shi, Huo Anxiang, Wang Chengrui, Zhang Naijian, He Mao, Cao Peiyuan, Li Jinyu, Wang Shizhi, Li Guangju, Bai Guangzhi, Liu Zhonghe, Mu Jim, Zhou Wende
1991, 15(S1): 1-6.
By using large-scale iron emulsion chambers, a big family event with visible energy ∑Eγ= 7631 TeV is obtained. The advantages of iron emulsion chambers in studying big families and the characteristics of the event observed together with a comparison with the Monte-Carlo simulation results are described.
The Trigger of Beijing Spectrometer
Guo Yanan, Yu Zhongqing, Ding Huiliang, Sheng Junpen, Yang Xirong, Gu Songhua, Li Qiming, Wu Xidong, Zhang Chunyan, Dong Aiping, Lin Fengcheng, Zhao Dixin
1991, 15(S1): 7-16.
This article describes the functions and decision process of the trigger of Beijing Spectrometer and explains its physical considerations and compositions individually.
The Fluid Theory of Self-Sustaining Magnetically Confined Electron Clouds (I) Fluid Equations
Yu Qingchang
1991, 15(S1): 17-24.
In this paper the axisymmetrical self-sustaining magnetically confined electron clouds are studied by means of the fluid theory. The electron clouds are maintained by the Penning discharge. The property of the electron motion in the clouds can be described with the fluid equations containing the continuity equation, the momentum equation, the energy equation, the Poisson equation and the heat transfer equation. The diffusion and escape of electrons and the energy transport in the electron clouds are discussed.
Gluon Fragmentation in e+e- Annihilations
Liu Ximing, Wu Huayou
1991, 15(S1): 25-32.
In this paper, we suggest that the gluon is hadronized by first splitting into a quark-antiquark pair. The final hadrons are produced by the color interactions among the quarks and antiquarks. Under this assumption,the calculated average charged particle multiplicities in e+e- three-jet events. The ratio of multiplicities between gluon and quark jets, and the rates of baryons in e+e- three gluons events all agree well with experiments. The angular distribution of final particles can also be explained.
Source Density Distribution and Intensity Interferometry in High-energy Heavy-ion Collisions
Liu Yiming, Huo Lei, Jiang Yuzhen, Wang Shan, D. Keane, S. Y. Fung, S. Y. Chu
1991, 15(S1): 33-41.
The fitted spatial parameter from intensity interferometry is related to an average radius <r> of the particle-emitting source. The mean-square radius〈r2〉of the source can be estimated by the small relative momentum correlation function. More detailed information about the source density distribution can be inferred from the value of k=<r2>/<r>2. A study of central collisions of 1.8 A GeV Ar + Pb at the Bevalac streamer chamber shows that the data are consistent with an a priori Gaussian model for the density distribution at the present level of experimental accuracy. The average radius of the pion source in the reaction is deduced, and a possible picture to describe the expanding pion source is presented.
The Possibility of Forming Bound State of η-Mesic Nucleus
Liu Jifeng, Shen Jianping, Li Guanglie
1991, 15(S1): 43-50.
The formation of the bound state of the η-mesic-aucleus is investigated by the standard Green's function method used in the many-body problem. It is found that when parameters, coupling constants and harmonic oscillator potentials are chosen in the physical range, due to the attractive nature of the ηNN*(l/2, 1/2-) interaction the η-16O bound state can possibly be formed. However, detecting such a bound state would be difficult, because its width Γ is larger than the binding energy of η in 16Oη.
A Systematic DWIA Analysis of the Conventional Mechanism for Pion Double Charge Exchange
Pan Lingjun, Jiang Huanqing, Zou Bingsong
1991, 15(S1): 51-61.
In the framework of the distorted wave impulse approximation,a systematic analysis is performed for the contribution of the conventional mechanism to the double charge exchange reaction to the double isobaric analog state. The effects of distortions of pions, nuclear wave functions, short-range correlation functions, parameters of the form factors, the spin-dependent term in the pion-nucleon amplitude, etc. are examined. It is shown that all these elements are very important and not negligible for the conventional mechanism. But after combining the effects of all these elements, the conventional mechanism is still not able to reproduce the experimental excitation functions and angular distributions for the energy region of 0-300 MeV. Therefore, the effects of some other mechanisms should be added.
A Microscopic Description of the Intruder State in Doubly Even Nuclei Near Closed Shells
Liu Yong, Qi Hui, Yang Zesen
1991, 15(S1): 63-71.
On the basis of the normal and proton 2p-2h excitation configurations, as well as the effective nucleon-nucleon interactions, a microscopic approach is proposed to investigate the properties of intruder state and configuration mixing in the doubly even nuclei near closed shells.
Cross Section Measurement of the 63Cu(n,α)60Co Reaction
Wang Yongchang, Yuan Junqian, Ren Zhongliang, Wang Huamin, Yang Jingkang, Shui Yongqing, Xiang Sicang
1991, 15(S1): 73-77.
The cross sections for 63Cu(n,α)60Co reaction are measured by taking the cross sections of 27Al(n,α)24Na reaction as the reference values and using the activation method in the neutron energy range of 13.6-14.8 MeV. The values of 583 ±3.1,563 ±2.4,53.4 ±2.0,50.8 ±1.9,48.4 ±1.7 and 47.4 ±1.7 mb are obtained at the 13.64,13.79,14.03,1433,14.60 and 14.80 MeV neutron energies, respectively. The results are compared with the published data. Neutron energies in the experiment were determined by means of the method of cross section ratios for 90Zr(n,2n)89Zr and 93Nb(n,2n)92mNb reactions.
Light-Particle Multidetector for the Intermediate Energy Heavy-Ion Reaction
Wang Bing, Zeng Yaowu, Shen Wenqing, Zhan Wenlong, Zhou Jianqun, Feng Enpu, Zhu Yongtai, Feng Jun
1991, 15(S1): 79-84.
A light-particle multidetector system was built for heavy-ion reaction mechanism research in intermediate energies (10-100 MeV/u). It is an array covering large solid angle (θ=5°-20°, φ=0°-360°) composed of 36 units, each of which covers an angular range of △θ=5°, △φ=30°. It can identify light particles (p, α,etc.) and give the information about energy, position and multiplicity of light charged particles. The tentative measurement results show that the satisfactory resolution for light particles identification can be obtained.
Single-Particle and Single Hole Energies in the 40Ca Region
Dou Zhiguo, Jing Xiaogong, Zhao Guoquan
1991, 15(S1): 85-92.
The single particle (SP) energy spectrum of 41Ca and the single hole (SH) energy spectrum of 39Ca are calculated with the SP Green's function. The matrix element of M-3Y force is employed as the equivalent G-matrix element The multi-scattering (MS) correlations of the two-particle-one-hole (2plh) and two-hole-one-particle (2hlp) mechanisms are studied. The result shows that the 2hlp MS correlation is more important than the 2plh MS correlation.
Rotational Effect on Electromagnetic Transitions After Band-Crossing
Xing Zheng, Wu Xingju
1991, 15(S1): 93-100.
The signature-dependence of B(M1)-values and dynamical quadrupole moments Q(1) and Q(2) after the band-crossing are investigated by means of an extended particle-rotor model. The calculated values are in qualitative agreement with the data. It is noted that in 159Tm the γ-value is quite different before and after the band-crossing.