1998 Vol. 22, No. 10

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Experimental Studies on Radiation Damage of China Made CsI(TI) Crystals
Zhu Yongsheng, Chen Yu, Shi Huanhang, Yu Chunxu, Liao Yihua, Xia Xiaomi, Lai Yuanfen, Zhang Zhuxiang, Zhong Xuechu, Zhang Caidi, Zheng Linsheng, Zhang Changchun, Chen Gang, Ren Shaoxia, Zheng Yanning, Liu Hu
1998, 22(10): 865-872.
The radiation damage of CsI(TI) crystals after irradiation in radiation fields formed by 1.3 GeV electron beams and Cobalt-60 radiative source are investigated. The variations of the light yield and the transmittance, the natural recovery and the heat annealling recovery of the radiation damage are measured.
Chaotic Behavior of Multiparticle Production in pp Collisions at 400GeV/c
Wang Shaoshun, Wang Zhaomin, Liu Ran
1998, 22(10): 873-877.
The entropy indices of QCD branching process are calculated from the data of 400GeV/c pp collisions. The nonzero values of entropy indices are obtained. The entropy indices are increased with decreasing average multiplicity's of the final states. It means that the is a chaotic sign in pp collisions at 400GeV/c.
Strange Particle Production in S+W Central Collisions
Chen Zhi, Ye Yunxiu, ruan Tunan, Sa Benhao, Tai An
1998, 22(10): 878-884.
The event generator LUCIAE has been used to simulate relativistic nucleus-nucleus collisions. The strange meson K0s and strange baryons A and A production in S+W central collisions at 200A GeV has been analyzed. The transverse mass spectrum for them and relative production rates of strange meson to strangebaryon are obtained and compared to the data of experiments.
Octupole Deformation in Neutron-rich 144,146Ce Nuclei
Zhu Lingyan, Zhu Shengjiang, Li Ming
1998, 22(10): 885-890.
The high spin states and octupole deformation collective bands of neutron-rich nuclei 144,146Ce have been established through measuring the prompt γ-rays from spontaneous fission of <252/sup>Cf. The highest spin state is up to 15. The characteristics of octupole deformation for the two nuclei are discussed.
The Calculation of the Fermion Condensates by Using the Improved Hamiltonian
Jiang Junqin
1998, 22(10): 891-895.
The Wilson fermion condensates in the lattice Schwinger model is calculated by using improved Hamiltonian and variational method. The calculated result depends on the Wilson parameter much weaker than before.
Effect of the Internal Line Particle's Finite Width on the Energy Loss of a Fast Moving Parton Penetrating Through QGP
Liu Xiaofei, Li Jiarong
1998, 22(10): 896-902.
Within the framework of linear response theory, we use the effective propagator including the internal line particle's finite width to study the energy loss rate of a fast moving parton's caused by the inducive field when it penetrates throught QGP, A reasonable interpretation to the numerical result is provided.
Three-Pion Interferometry at Small Relative Momentum in Relativistic Heavy-Ion Collisions
Chen Xiaofan
1998, 22(10): 903-909.
With the power series expansion of the three-pion correlation function at small relative momentum, the relation between the three-pion correlation and root-mean-square radius of pion source is Obtained analytically. The relations between the space parameters of the pion source from 3π interferometry and 2π interferometry are also obtained when multi-pion correlation in three-pion events is or is not considered,The distortion of the two-pion coherence factor caused by the multi-pion correlation in three-pion events is calculated. And comparison is made between the results of 2π interferometry analyses at small relative momentum and the experimental measurements of the central relativistic heavy-ion collision 1.8A GeV Ar+Pb.
Quantum Statistical Effect in Production of K and π Mesons
Lu Zhongdao
1998, 22(10): 910-914.
The quantum statistical effect for K and π production in 200A GeV S+S and S+Ag collisions is studied. The calculated results reproduce the experimental data well. The extracted freeze-out temperature is ~110MeV and the baryon density is ~0.05ρ0.
Descriptions for Nuclear System with Only One Geometrical Symmetry Plane
Luo Wendong, Li Xunjun
1998, 22(10): 915-919.
The descriptions for nuclear shapes in a general case are discussed, and the symmetry properties for nuclear systems of different shapes are presented. The corresponding numerical algorithms are constructed.
Dependence of the Nucleon Mean Free Path and Relativistic Microscopic Optical Potential on Temperature and Density in the Relativistic Model
Sun Xiuquan, Zhang Zhengjun, Zhang Jianshu, Han Yinlu, Shen Qingbiao
1998, 22(10): 920-927.
The relativistic microscopic optical potential,the Schrodinger equivalent potenlial and mean free paths of a nucleon at finite temperature in nuclear matter with different nuclear density are initially studied on the basis of Walecka' s model, the thermo-fielddynamics and the relativitic Dirac-Brueckner-Hartree-Fock approach. The calculatted results show that the dependences of the Schrodinger equivalent potential and mean free path of a nucleon on nuclear density are fairly sensitive and the dependences on nuclear temperature become more sensitive when nuclear density is larger.
Systematic Evolution of Projectile Fragmentation Process with Incident Energies
Wu Zhongli
1998, 22(10): 928-931.
The reduced widths of the momentum distribution of the projectile-like-fragments from the fragmentation process are calculated for fitting the experimental data in a wide energy domain based on a quantum statistic physics model. The systematic evolution of the fragmentation process with incident energies is discussed.
A Novel Control System for RF Power System of LINAC
Li Fengtian, Xie Jialin, Wang Yanshan, Wang Bosi
1998, 22(10): 932-936.
This control system is used to flatten the flat-top of the amplitude and phase macro-pulses of the high power klystron output.This is of critical importance in improving the electron beam quality for FEL and other applications. The self-adaptive feed-forward control system is adopted to stabilize the RF power supply for the LINAC, which utilizes linearization and matrix algebra to simplify the computation. The system is operational and some experimental results have been obtained, which demonstrate that the system is effective to improve the beam quality.
The RF Quadrupoles in the RFD Structure
Zhang Mutian
1998, 22(10): 937-942.
The character of the newly developed RFD structure is studied by means of lens approximation. The equations of particle motion functions, transfer matrices of RF lens and stability conditions of particle acceleration are presented.
Simulation of Halo Formation in Breathing Round Beams in a Uniform or Periodic Focusing Channel
Huang Zhibin, Chen Yinbao
1998, 22(10): 943-950.
It is shown that beam self-field effects induce nonlinear resonances and chaotic behavior in uniform or periodic focusing channel by means of particle-core model and Poincare mapping technique. In order to explore self-consistently the fundamental properties of breathing round beams propagating in a uniform channel, the initial phase-space distribution of a beam injected into a linac is adopted to be a sufficiently realistic distribution such as Gaussian, waterbag and parabolic distribution Multiparticle simulations are performed and a series of results such as halo intensity and emittance growth are obtained.
Radiation Character of 3W1 Permanent Magnet Multipole Wiggler
Tang Esheng, Huang Yuying, Wu Yingrong, Yi Futing
1998, 22(10): 951-954.
The beam intensity and its distribution from the new installed 3W1 Wiggler at Beijing Synchrotron Radiation Facility of BEPC were measured. The experimental results quite consist with the theoretical calculation.
Searching for Dibaryon With Pion-Nucleus Double Charge Exchange Reaction
Ma Weixing
1998, 22(10): 955-958.
The dibaryon mechanism is suggested for Pion-Nucleus double charge exchange reaction. The calculations within this mechanism are performed for 18O(π+) 18Negs reaction at the energy of 164MeV.The principal finding from this study is that the dibaryon mechanism may exclusively be responsible for solving many long-standing puzzles of 164MeV double charge exchange reaction on the target 18O.
New Heavy Neutron-Rich Nuclide 209Hg
Zhao Jinhua, Zhang Li, Zheng Jiwen, Wang Jicheng, Qin Zhi, Yang Yongfeng, Zhang Chun, Jin Genming, Guo Guanghui, Du Yifei, Guo Tianrui, Wang Tongqing, Guo Bin, Tan Jinfeng
1998, 22(10): 959-960.
The new neutron-rich nuclide 209Hg has been identified for the first time. An on-line, gas-thermochromatographic technique was developed for rapidly separating mercury isotopes produced by 600MeV 18O+(thick target) reaction. A special detection method was used to detect the - delayed rays from neutron-rich mercury isotopes. The half-life of 209Hg was determined to be 35+9-6s.