1992 Vol. 16, No. 7

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Experimental Investigation for the Decay Rate of Orthopositronium
ZHANG Tian-Bao, YANG Guang-Ming, GUO Bao-Nian, WANG Hai-Dong
1992, 16(7): 577-581.
A method for the measurement of the vacuum decay rate λ0 of orthopositronium is suggested and the preliminary result is obtained λ0=7.034±0.013μs-1.The possibility for the improvement of the experiment has been discussed.
Theoretical Calculation on the Adjustment of Double Crystal Monochromatic Beam Line
QIAO Shan, XIAN Ding-Chang
1992, 16(7): 582-587.
Calculation has been made when we adjust 4W1B beam line in Beijing Synchrotron Radiation Facility.The relation among the intensity,energg dispersion,energy accuracy of the monochromatic beam and all adjustable freedoms is acquired.The reasonable procedure and the precision requirement of adjustment for each freedom are given.
The Phase Transition in Z(N) Potts Spin Model: An Analytical Analysis
SONG Yong-Shen, CUI Jian-Ying, YANG Ji-Min, LU Gong-Ru, LIU Wen-Sheng
1992, 16(7): 588-595.
We study the phase transition in Z(N) Pots spin model by an analytical approach—the generalized cumulant expansion with mean field approximation.As a test,we perform the expansion to the third order correction for Z(3),Z(4),Z(5) and Z(60 cases.The critical points turn out to be closer to the exact values when higher corrections are taken into account.
Path Integral Light-Cone Quantization of a Gauge Theory of Self-Dual Fields
MIAO Yan-Gang
1992, 16(7): 596-599.
For a gauge theory of self-dual fields,whose S-matrix element manifestly including the self-duality constraint is obtained by using the path integral light-cone quantization.
Soliton Star in FL-non-topological Soliton Model and Its Behavior at High Temperature
SIONG He-Jin, LI Jia-Rong
1992, 16(7): 600-608.
In this paper.based on the FL-non-topological soliton model,we discussed the possibility of the formation of the FL-soliton star and its behavior at high temperature.We find that the stable,cold and spherical FL-soliton star can be formed,under the necessary condition W>3B.At high temperature,the FL-soliton bag disappears by the phase transition,but there may be some stellar configuration.
On the Exchange Algebra of Periodic WZNW model
1992, 16(7): 609-614.
Using the free field representation,we calculate,the r-matrix and classical exchange algebra for WZNW model under periodic boundary condition,and discuss the quantum counterparts of the exchange algebra as well as the performances of the r-matrix and classical exchange algebra under Hamiltonian reductions.
Glant Monopole and Quadrupole States in a Chiral Breaking Field Theory
ZHANG Qing-Lan, QIU Xi-Jun
1992, 16(7): 615-622.
The saturating chiral breaking field theory are used to study the compressibility of the Fermi-liquid and the excitation energies of the giant monopole and quadrupole states in the framework of mean-field theory.It is found that the compressibility of the Fermi-liquid in the nuclear system,and the excitation energies of the giant monopole and quadrupole states are more close to the experimental values in comparison with the results of the σ-ω model.
The Influence of Nuclear Target on “Small” Mass Lepton Pair Production of High Energy Hardon-Nuclei Collision
GAO Yong-Hua, HE Zhen-Min, HUANG Rui-Wang, PENG Hong-An
1992, 16(7): 623-632.
Based on Drell-Yan Mechanism modified by pertubative QCD and taking account of the contribution of vector meson states,we analyzed and explained the data of the WA-78 group ni (π,P)+A→μμ+X process at 2mμμμ<1.5GeV and 0.1F<0.6 with the use of the rescaling model and the recent accurately measured data of the NMC Group for the ratio of structure functions RA(x,Q2) in 1-A deep inelastic scattering process at 0.00352<90MeV2/c2.In our analysis,after comparison with the data of the CIP group for the same process but at different mll and xF regions,we gave a good explanation for why the influence of nuclear target displays a strong shadowing effect in former case while a strong antishadowing effect in latter case.By the rescaling model and other reasonable assumptions,we showed it is intimately connected with the above mentioned the RA(x,Q2) and thus further revealing the essential connection for the influence.
Monte Carlo Investigation of Fractal Structure of Multiparticle Production in High Energy Collision
YU Lian-Zhi, LIU Lian-Shou, CAI Xu
1992, 16(7): 633-639.
Fluctuations of the produced particles of the final states in high energy collisions may be the break through for investigating multi-particle dynamics.How to eliminate the statistical noise of the system is one of the most important problems.In this paper the influence of the statistical noise on fractal structure is analysed and a kind of method for eliminating statistical noise is proposed by using the Monte Carlo simulation based on a simplt dynamical model.
Measurement of the Complets Fusion Excitation Function for the 16O+28Si Reaction
ZHENG Ji-Wen, ZHENG Zi-Ping, LIU Guo-Xing, CHEN Ke-Liang, WANG Su-Fang, BAI Xing-Ping, YU Xian, ZHANG Huan-Qiao, XU Jin-Cheng, LIU Zu-Hua, RUAN Ming, LV Jun, XU Kan
1992, 16(7): 640-646.
The complete fusion excitation function for the 16O+28Si reaction is measured in the range of 50—90MeV with step of 1.0MeV.It is analysed by using some theoretical models and the model parameters are extracted from this analysis.Gross structure is found in the excitation function when ECM<46MeV.The energies of peaks are 34.5,38.5 and 43.0MeV,respectively.The structure vanishes gradually when ECM>46.0MeV.
Preliminary Observation of Proton-rich Isotope 65As
XU Hu-Shan, JIANG Cheng-Lie, BAI Xi-Xiang
1992, 16(7): 647-650.
The proton-rich isotope 65As was observed preliminarily by 20.11A MeV 64Zn beam bombardment on a 17.2mg/cm2 Be target.The detecting system comprising a magnetic facility RIPS,a PPAC,an ionization chamber,and a PSSD was used to identify the charge states,atomic numbers,and masses of the reaction products.
The Shape and Potential of Hot Nuclei in Symmetry Ternary Fission
DAI Guang-Xi
1992, 16(7): 651-657.
A symmetry ternary fission (STF) shape with a spherical residue plus 3 rose-leaf-like rotating bodies (SRRL) has been proposed to describe the large deformation process from sphere to scission point with one deformation paramenter.By LDM,the relative Coulomb and surface potential with sharp surface have been calculated; as a example in several nuclei we present STF collective potentials,from which the shape and barrier height in saddle point and TKE determined by coulomb energy in scission are given.Also the shift of C.M.for each prefragment in STF process and the deformation energy for new born fragment are obtained.Considering the dependence of nuclear surface tension on nuclear temperature,the STF barrier height for hot nuclei would be decreased and then the STF probabilities over the barrier would increase too.The calculated results in the SRRL have been compared with previous results by oblate shape model.
Evolution of Heavy Ion Reaction Mechanism is the Energy Region of 10 to 100MeV/A
ZHU Quan-Ling, GE Ling-Xiao, LI Zhu-Xia
1992, 16(7): 658-665.
The dynamical process of heavy ion collisions in the energy region of 10 to 100MeV/A has been investigated by Quantum Molecular Dynamics model.According to the calculated mass distribution of clusters,the time evolution of mass distribution and density distribution,the reaction mechanism and its characteristic are predicted and compared with those obtained from the BUU model.
Excitation Energy in Heavy Ion Collisions
ZHANG Feng-Shou, GE Ling-Xiao
1992, 16(7): 666-669.
With Hartree-Fock approximation,the relation between excitation energy and temperature has been obtained and discussed for both infinite nuclear matter and finite nucleus Pb208.
Solutions in Riemannian Space-Time of Arbitrary Dimension
LI Fu-Bin
1992, 16(7): 670-672.
By analysing specific examples,it is shown that the Schwarzchild solution and the Booth's solution are a genus of solutions in space-time of arbitrary spatial dimension.