1999 Vol. 23, No. 10

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Quasi-Elastic Collision and Coupled Channel Analysis in 18O+148Nd
Zhao Kui, Li Tianxin, Guo Jiyu, Lu Xiuqin, Fu Changbo, Cheng Yehao, Li Shuyuan
1999, 23(10): 937-945.
Angular distributions of the elastic and inelastic scattering of 18O+148Nd at 90.72 MeV were measured by using the Q3D magnetic spectrometer as well as the focal plane detector system. The experimental results were reproduced by DWBA and Coupled Reaction Channel calculation code FRESCO. The polarized potential was introduced in the DWBA calculation and the similar results with the Coupled Channel calculation were obtained. The interference effect of nuclear-Coulomb in the inelastic exciting was discussed and the approximate factor describing the interference intensity were reduced.
Measurement of Fission Time Scale and Excitation Energy at Scission for 25MeV/u 40Ar+209Bi Fission Reaction
Zheng Jiwen, Wu Enjiu, Zhang Chun, Xiao Zhigang, Wang Sufang, Yin Shuzhi, Jin Genming, Tan Jilian, Jin Weiyang, Song Mingtao, Li Zuyu, Wu Heyu, He Zhiyong, Yin Xu, Peng Xinping, Jiang Dengxing, Qian Xing
1999, 23(10): 946-953.
Alpha particles detected in coincidence with two fission fragments in the reaction of 25MeV/u 40Ar+209Bi have been measured at the backwards angles of 145° and 95°, respectively. The spectra at each angle are incremented in two different intervals of linear momentum transfer(LMT). These two intervals of LMT correspond to two considesably diffesent initial excitation energies, =472 and 595MeV, in the primordial hot nuclei formed in the reaction. The moving source analysis of the spectate has been used to extract the prescission and postScission alpha particlemultiplicities, as well as other relevant qualities such as the temperatures of the target-like residues and fission fragments. The excitation energies at scission, deduced from the postscission α pasticle multiplicity are about 166 and 179 MeV in the two LMT intervals, respectively. Compared with the considesable difference of initial excitation energies, the near equality shows that the excitation energy at scission are not explicitly dependant on the initial excited state of the fission nuclei. The fission bine scale of hot nuclei with excitation energy of 470-600MeV, deduced from prescission multiplicity, is about 4×10-21 sec, which indicates that the so-called fast fission dominates in the fission channel of hot nuclei in this excitation energy range.
Searching for 1-+ Exotic State in J/ψ Decay Process J/ψ→ρρπ
Shen Qixing, Yu Hong
1999, 23(10): 954-960.
The formulas of moment for J/ψ decay process J/ψ→ρρπ in two-state coupling case are given by using the generalized moment analysis and two-state coupling treatment method. It presents a possible way to search for 1-+ exotic state and determine its character in the J/ψ decay process.
Algebraic Bethe Ansatz for the Supersymmetric t-J Model With Reflecting Boundary Conditions in FBF Background
Xi Xiaoqiang, Shi Kangjie, Hou Boyu, Fan Heng
1999, 23(10): 961-979.
In the framwork of the graded quantum inverse scattering method (QISM),we obtain the eigenvalues and eigenvectors of supersymmetric t-J model with reflecting boundary conditions in FBF background. The corresponding Bethe ansatz equation are also obtained.
The Extention of Berry's Theory on Geometric Phase
Zhang Zhongcan, Fang Zhenyun, Hu Chenguo, Sun Shijun
1999, 23(10): 980-991.
To the cyclic Hamiltonian system, where we have done the parameter transition t→R(t), we study the problem of the acquirement of Berry geometric phase γn (C) by the "strict" evolution from the non-adiabatic to the adiabatic-limit. Our results show that there exist four types of evolution states, all of which can satisfy the above "strict" evolution along the same closed curve C in the space formed by the parameter R and can obtain the same Berry geometric phase γn(C). When Berry first found the geometric phase γn(C), he only considered one evolution state, which is just the adiabatic approximation case of one of the four "strict" evolution states mentioned above. So Berry's theory on geometric phase can be extended into the four types of strict evolution shown in this paper.
Multifractal Dimension and Dynamical Fluctuation Strength in High Energy Multiparticle Final States
Fu Jinghua, Wu Yuanfang, Liu Lianshou
1999, 23(10): 992-997.
relation between the multifractal dimension and the strength of dynamical fluctuations is studied in some detail. A parameter "effective fluctuation strength" is proposed to characterize the strength of dynamical fluctuations in the multiparticle final states of high energy collisions. Its application region and the method for extracting its value from the experimentally observed data is given.
An Algorithm for Increasing the Ratio of QGP Candidate Events in Relativistie Heavy Ion Collision Data Sample Using Factorial Moment Technique
Cheng Qinghua, Hu Yuan, Liu Lianshou
1999, 23(10): 998-1003.
The formation of quark-gluon plasma (QGP) in relativistic heavy ion collision, is expected to be accompanied by a background of ordinary collision events without phase transition. In this short note an algorithm is proposed to select the QGP candidate events from the whole event sample. This algorithm is based on a simple geometrical consideration together with some ordinary QGP signal, e.g. the increasing of K/π ratio. This algorithm increases the "signal to noise ratio" of QGP events in the selected sub-sample in shown explicitly by using Monte-Carlo simulation.
Theoretic Calculation and Analysis for Neutron Induced Reaction on 12C Below 20MeV
Cao Ligang, Sun Xiuquan, Zhou Jinfeng, Han Yinlu, Zhang Jingshang
1999, 23(10): 1004-1009.
A new method for light nucleus reaction has been developed based on the unified Hauser-Feshbach and exciton model. The nuclear data calculation for n+12C reaction, as example, has been performed in order to study the mechanism and the characteristic. The comparisons of total outgoing neutron and alpha particle with the measured experimental data indicate that the way of calculation for light nucleus reaction are successful.
Collective Rotation Effect in Heavy Ion Collision and the Characteristics of Reaction
Lu Zhongdao, Ye Wei, Shen Wenqing
1999, 23(10): 1010-1014.
The effect of collective rotation and the reaction characteristics are studied for intermediate energy heavy ion Collision. The maximum impact parameter, the reaction centrality, the average collective rotation energy and the angular velocity,which characterize the heavy ion collisions, are deduced. For 10.6 MeV/u 84Kr+27Al→111In fission reaction, it is found that this reaction has high degree of collision centrality. the average collective rotation energy is larger than one-third of the total excitation energy, and the composite nuclear system rotates about 8.8 turns before breakup.
Analysis on Superdeformed Bands by Using I(I+1) Expansion
Zhou Xianrong, Xu Fuxin
1999, 23(10): 1015-1023.
The superdeformed bands in the A-190 and 150 regions are systematically analyzed using four-parameter rotational spectra formula of Bohr-Mottelson's I(I+1) expansion. The result shows that the superdeformed bands in the A-190 and 150 regions can be described very well with four-parameter ABCD-formula. The theoretical values of J(2) of most of nuclei accord with the experimental extracted values. The four-parameter value relation doesn' t support the theoretical expected values of ab and Harris formula, but comparatively the theoretical expected value of ab formula agrees with the experimental extracted values better than that of Harris formula.
Potential Well Distortion Effects and Bunch Shift Compensation
Wang Lanfa, Lin Yuzheng
1999, 23(10): 1024-1032.
An analytic treatment of multi-bunch potential well distortion for general bunch distribution case along one storage ring is presented. Resulting simple analytic formulas describe the mode loss and the synchrotron tune shift experienced by a given bunch within the beam, as a function of the resonance frequency. We can know how to modify the existing configuration of parasitic cavity resonance (via frequency tuning) so that the resulting potential well distortion effects are minimized. We can also know how to compensate the bunch shift by using sub-RF cavity.