1994 Vol. 18, No. 4

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Relative Information Entropy of Particle Production in High Energy Induced Nuclear Reactions
1994, 18(4): 289-295.
A new characteristic quantity called relative information entropy R is introduced,which is employed to investigate the multiplicity distribution of produced particles in 14.6. 60, 200 A GeV oxygen ions and 200 A GeV sulphur ions induced nuclear reactions. It is found that R is insensitive to energy. R increases with the size of rapidity window and rapidly reaches saturation, which explores the fact that the entropy is concentrated in the central rapidity region. The experimental results are in good agreement with the prediction of the FRITIOF simulation of the Lund model.
Identification of 208Hg
Zhang Li, Jin Genming, Zhao Jinhua, Yang Weifan, Yang Yongfeng, Zhao Zhizheng, Zheng Jiwen, Sun Xiurong, Wang Jicheng, Li Zongwei, Qin Zhi, Guo Guanghui
1994, 18(4): 296-301.
This paper describes in detail the procedure used in identifing the new neutronrich isotope 208Hg and measuring its half-life. The idetification included two-step chemical separations. The first step was the collection of Hg element products from the irradiated target with a high efficiency and good element selectivity, which was realized by means of an off-line melt Ph target device. The second step was to extract periodically the growing T1 element from the collected Hg sample. In the γspectra of the extracted T1 samples a 2614.6keV γ activity with a half-life of 3min was observed, which may only be assigned to the daughter 208T1 of 208Hg β decay.
Application of maximum likelihood method in reconstruction of charged particle tracks
Chen Tingyang
1994, 18(4): 302-309.
By use of the maximum likelihood, a new method to fit space tracks with nonGaussian measurement errors is introduced. Compared with the conventional least squares fit, the resolution has been greatly improved and so does the reliability of distinguishing the false tracks.
Transient Beam Loading Problem in Constant Gradient Accelerator Structure
Huang Yongzhang, Wu Gang
1994, 18(4): 310-316.
This paper starts with the general solution of the transient beam loading problem for a constant gradient travelling wave accelerator structure (SLAC type structure) by using the energy conversation law. In case where the electron beam in the accelerator comes from a thermionic microwave gun, the electron current increases with time, the beam loading problem is treated for the first time, and the analytic solution is used to analyse the linear accelerator of Beijing Free Electron Laser.
An SU(5) Grand Unified Model with Hadrons as Nontopological Solitons(Ⅰ)
Chen Shihao
1994, 18(4): 317-325.
A new grand unified model containing the known three generations of quark and lepton in which hadrons are regarded as nontopological solitons formed from quarks is presented. According to the model leptons and quarks are the same in essence. The differences between them are caused by spontaneous symmetry breaking.When a quark is located inside a hadron, its properties will be the same as those of a known quark and its mass very small. When a quark is outside hadrons, its properties will be the same as those of a known lepton, its mass very large and it Will rapidly decay. Except defining charge Q0 and fermion number F0 which are exactly conserved, we also define interior colour, interior charge and interior fermion number approximatly conserved inside a hadron. The (L-B) conservation in the known SU(5) model corresponds to the fermion number number Fo conservation in the present model.
The Clustered Production of Final Particles and ForwardBackward Correlation in High Energy pp Collision
Zhang Yang, Liu Lianshou
1994, 18(4): 326-333.
In this paper, forward-backward multiplicity correlation in various rapidity windows in high energy p collision is obtained by using Monte Carlo simulation based on Three Pire Ball model with cluster mechanism. The results fit the exprimental data of s=200,546,900GeV, indicating that the model is reasonable. It is shownthat the effect of cluster mechanism makes forward-backward multiplicity correlation increase in short range and decrease in long range.
Multiplicity and Angular Distribution of Projectile Fragments in Relativistic Nucleus-Nucleus Collisions
Liu Fuhu, Tang Xiaowei
1994, 18(4): 334-339.
In this paper the multiplicity and angular distribution of projectile fragments produced in relativistic nucleus-nucleus collisions are discussed. The probability distribution of multiplicities, as well as the probability distribution of angles are given. The calculated results are compared with the experimental data in the energy range from 15 to 200 GeV/N, they are in good agreement within experimentalerrors.
Fission Probability Calculation by Solving Fokker-Planck Equation With Variation Method
Zhong Yunxiao, Hu Jimin
1994, 18(4): 340-346.
A variational method is developed to solve Fokker-Planck (F-P) equation. One dimensional fission probability is calculated and compared with other methods. The relation of F-P equation and Smoluchowski equation is discussed in light of thismethod, which gaves the way to derive the multi-dimensional Smoluchowski equation with varying mass and viscosity and to solve more complicated F-P equations.
Description of Charged Particle Multiplicity Distribution in High Energy Strong Interaction
Qin Keyu
1994, 18(4): 347-352.
With the assumption that the probability for n-charged particles production inhadron-hadron collision is Pn=xPn(1)+(1— x)Pn(2), whithin Pn(1)= andand proper choice of 1, 2, k and x, the true multiplicity distribution in full phase space can be described successfully at the centre fo mass energy GeV. Using the experimental data of non singe-diffractive collisions between proton and antiproton at centre of mass energies of 200 and 900GeV, the supposition had beenexamined and confirmed: it is very good to describe the facts. Had been discussed the theoretical bases of supposition.
A study of spectra of nuclei of three bosons
Zhang Qingying, Chen Xiaolin, Feng Mang, Que Jianzhong
1994, 18(4): 353-360.
The spectra of nuclei of three bosons are calculated with the boson surface delta interaction in the framework of Interacting Boson Model, the E2 reduced transition probabilities B(E2) of some nuclei are also calculated. The agreement between theoretical and experimental results is satisfactory. It is shown that the model is successful.
On Theoretical Analysis of Kramers' Stationary Solution in the Diffusion Model of Fission
Feng Renfa, Wu Xizhen, Zhuo Yizhong
1994, 18(4): 361-365.
According to the non-equilibrium diffusion model of nuclear fission, the fission process can be described by the Fokker-Planck equation (F-P eq.). Through comparison of the exact solution of F-P eq. numerically with the Kramers' stationary results, the success and drawback of Kramers' stationary solution have been pointedout.
The 2νββ Decay Lifetime and the Shell Model Wavefunction in 82Se
Wu Huifang, Song Changliang
1994, 18(4): 366-370.
The 2vββ decay lifetime of 82Se is a first direct laboratory measurement of the double β decay. Its theoretical calculation can be given by using a simplified shell model wavefunction in the two-nucleon mechanism. It is shown that this prediction is good in agreement with the experimental value by adequately adjusting the parameters in the shell-model calculation.
Description of the Properties of nuclei far from βstability line in relativistic Hartree approach
Chen Baoqiu, Ma Zhongyu
1994, 18(4): 371-378.
In the usual relativistic mean field(RMF) calculation of stable nuclei, the tensor coupling of ρ meson is not taken into account. It is necessary to clarify thecontribution of the tensor coupling of ρ meson when the RMF is extended to nucleifar from β stability line. The tensor coupling of ρ meson is included and its effectis discussed in the present work.
Effect of N,Z Dependent Macroscopic Potential to cluster Formation in Quantum Molecular Dynamics
Li Junqing, Liu Jianye, Zhao Enguang, Zhu Quanling
1994, 18(4): 379-384.
Based on the QMD model, in addition to the Skyrme-type, Yukawa and Coulomb interactions, a macroscopic potential, which is dependent on the neutron andproton number N,Z of the cluster and consists of the symmetrical energy of liquiddrop model and shell and pairing correction energies, has been taken into account.It improved the reasonable structure of the cluster formation in heavy ion reactionswith intermediate energy.