1995 Vol. 19, No. 1

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Primary Vertex Fitting in BES
Jiang Zhijin, Wang Taijie, Huang Tao
1995, 19(1): 1-7.
In this paper,the principle of primary vertex fitting of BES has been described. Some modifications to the original program are made and the vertex distributions for the experimental data of Run462—961 are presented.
Behaviour of Prompt Gamma-Ray Emission in ColdFission of 252Cf
Han Hongyin, Li Anli, Chen Jinhua, Huang Shengnian
1995, 19(1): 8-15.
The behaviour of prompt γ-ray emission in the cold fission of 252Cf was investigated experimentally using a four-parameter correlation technique. A twin gridded ionization chamber was employed to detect the fission signals and to determine the fragment emission angles, and a φ10cm×10cm NaI(T1) detector was used to record the γ-ray energies. The result shows that the angular distribution coefficient of γ-rays emitted in cold fission is twice as large as that in the normal fission.The fact that in the cold fission the number of γ-rays emitted from the light fragments is approximately three times as large as that from the heavy ones can not be explained satisfactorily so far.
Study of the Boson Resonance Produced in the Three-Step Two-Body Decay Process of J/ψ
Shen Qixing, Yu Hong, Zhang Lin
1995, 19(1): 16-26.
The three-step two-body decay process of J/ψ,J/ψ→V+X,X→P1+ Y,Y→P2+P3 is discussed using the generalized moment analysis method. The spin, parity and the ratios of helicity amplitudes of boson resonance X can be determined in terms of the measurement of the corresponding moments except a very special case.
Possible Explanation of the Negative Values of m_ve~2Obtained from the β-Spectrum Shape Analyses
Qing Chengrui, He Zuoxiu, Liang Dongqi, Mao Yajun, Chen Shiping, Sun Hancheng
1995, 19(1): 27-33.
By comparing the results obtained using the same experimental data of CIAE but different theoretical formula fits it is pointed out that the negative value of mv2 is most likely stemmed from inaccuracy of the theoretical formula of the β-spectrum.
Double Pomeron Exchange and J/ψ,γ Production Processes in High Energy p+p(p)Collisions
Peng Hongan, Qin Kecheng, He Zhenmin
1995, 19(1): 34-41.
The double diffractive J/ψ, hard production processes is discussed. Assuming that Pomeron has parton distributions and dominated by gluons with behavior as 1/x when x is small, the energy dependance of the cross section, for above processes is calculated and compared with both the cross section of single diffractive hard scattering and of Drell-Yan processes . It is shown that the is similar with and increases as (lnS)2 at superhigh energies. It is emphasized that this character may provide a new method for detecting physical particles at energy ranges of SSC.
Cluster Monte-Carlo Algorithm for the Study of Quantum X-Y Model
Ji Daren, Ying Heping, Chen Feng, Zhang Jianbo
1995, 19(1): 42-48.
A Monte-Carlo study for the one-dimensional quantum X-Y model by cluster algorithm is presented. For lattices of L=32, 64 and 128 and at βJ=1.0-10.0 temperature region, the dynamical properties are analysed carefully and the corresponding thermodynamical quantities are computed. This method may be developed to apply for the lattice fermion systems.
Transverse Energy Dependence of Yield of Charmonium Production in Relativistic Heavy Ion Collisions
Chao Weiqin, Liu Bo
1995, 19(1): 49-52.
Based on the geometrical model and absorption mechanism. transverse energy dependence of the yield of charmonium production relative to muon pairs in the mass continuum region in relativistic heavy ion collisions is analysed. Our results fit the data very well. It is shown that nuclear effect is important in explaining the charmonium suppression.
Dynamical Study on Processes of Intermediate-Energy Heavy Ion Collisions
Liu Jianye, Zhang Shaoguang
1995, 19(1): 53-58.
Using the modified QMD (MQMD), the intermediate-energy heavy ion collision dynamics and the multifragmentation mechanism are investigated. The dynamical ingredients governing the multifragmentation process and collision dynamics in heavy ion collisions are discussed.
Three-Body Model of 11Li
Duan Yiwu
1995, 19(1): 59-63.
A new effective interaction between a neutron and the 9Li core is introduced, and based on the n+n+9Li model, a variational calculation on the neutron rich nucleus 11Li is completed. The one-body density, formfactor and shapedensity are investigated, The RMS radius and the binding energy are also calculated and are in good agreement with the experimental data.
Structure of Pb Isotopes and Residual Interaction
Gu Jinnan
1995, 19(1): 64-72.
In the framework of shell model the structure properties of Pb nuclei (A=204,205,206) are calculated and stutied using MSDI and Kuo-Hening interaction as a residual interaction between the neutron holes. Overall comparison of the calculation results for MSDI and Kuo-Herling interaction shows that MSDI works well too in describing the properties of nuclei in Pb region. In addition the method for judging the TBME from. experimental data is also discussed.
Matching Problem of Lattice with Transverse Coupling
Xu Jianming
1995, 19(1): 73-81.
The matching problem of lattice with transverse coupling has been discussed in this paper. The matching conditions and the related equations of the effective beam emittance are given.
New Soft X-Ray Reflectometer on Beijing Synchrotron Radiation Facility and Some Basic Results of Physics Work
Cui Mingqi, Wang Jun, Miao Jianwei, Huang Yuying, Tang Esheng, Xian Dingchang, Shao Jinghong, Xue Song, Xu Zhengliang, Sun Jianhui
1995, 19(1): 82-86.
This paper describes the new soft X-ray reflectometer with multilayer monochromator on beam line 3B1 of Beijing Synchrotron Radiation Facility (BSRF). The transmitted spectrum of aluminum filter and reflected spectrum of Nb/Si multilayer in soft X-ray region have been analysed with this reflectometer. The reflectivity of a Nb/Si multilayer manufactured in our group (41 layers, d = 13.45 and wavelength near 17.59um at 42 deg.) has been measured to be 32%.
Zhang Jianhua, Qi Lijie, Shen Pengnian, Zhang Zongye, Yu Youwen
1995, 19(1): 87-92.
The spin-orbit interactions between two quarks due to the one-gluon exchange,the confinement potential, the σ exchange of chiral field and the twogluon exchange are all considered in our calculation. As a consequence the spin-orbit splitting of 1P state in the baryon spectrum and the 3P2 phase shifts of the N-N scattering can be well explained simultaneously.
New Suppression Mode of the ψ(2S) Hadronic Decay
BES Collaboration
1995, 19(1): 93-96.
The hadronic decays ,and ωf2(1270) have been studied in a sample of 1.27 million produced.Measurements of their branching fractions are presented. While obeys the "14% rule" predicted by theory, →ωf2 (1270) is suppressed comparing with the corresponding decay. As a vector-tensor pair combination, the ωf2 mode is the first example of a non-vector-pseudoscalar decay of charmonium which violates the above mentioned rule.