1993 Vol. 17, No. 9

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A Method For Identifying Medium-Heavy Products of Heavy Ion Reaction At SPEG Spectrometer
FENG Jun, SHEN Wen-Qing, MA Yu-Gang, ZHAN Wen-Long, ZHU Yong-Tai, GUO Zhong-Yan
1993, 17(9): 769-774.
A method for identifying medium-heavy products of heavy ion reaction on magnetic spectrometer is discussed.The determination of the charge state,atomic number,atomic mass of fragments of 44MeV/u 129Xe on 90Zr and 197Au target are described.This is the first time to identify such heavy reaction products on the magnetic spectrometer at intermediate energy.
Microstructure of A1/GaAs Interface Studied by Slow Positron Beam
WENG Hu-Min, ZHOU Xian-Yi, XU Ji-Hua, SUN Shi-Jun, ZHU Jing-Sheng, WU Shu-Lan, HAN Rong-Dian
1993, 17(9): 775-783.
A series of interface models were founded,and the expressions of relation between Doppler Broadening S-parameter and implanted energy of positrons were obtained from the diffusion equation of positrons.Interfaces formed between Al and (110) surfaces of GaAs were studied with Slow Positron Beam.The system of A1/GaAs interfaces could be illustrated by perfectly absorbing linear interface model.From the results fitted by the model,the relation between the S-parameter of interfaces and the annealing temperatures or the thickness of films was derivtd and the microstructure of interfaces and its dynamical characters discussed.
The Study of the Silicon Microstrip Detector
MAO Yu-Fang, GUO Zhao-Qiao, ZHANG Xiu-Feng
1993, 17(9): 784-789.
A silicon microstrip detector has been fabricated by the new method of planar process.A high-ohmic (~3kΩ.cm)n-doped silicon crystal,oriented in the <111> direction and 400μm thick is used as base material.The sensitive area of the detector (18mm×12mm)is covered with p+ implanted diode strips and Al contacts (300 strips,20μm width and 40μm pitch).The leakage current is 5×10-9A at the reverse bias voltage of 100V.The distribution of charge collections of the silicon microstrip detector was measured and 5.3μm of the spatial resolution was obtained.
Design and Fabrication of Alpha Magnet for an Microwave Electron Gun
HUANG Yong-Zhang, TENG Ke-Jian, XIE Jia-Lin
1993, 17(9): 790-795.
This paper gives the motion of electrons in the alpha magnet firstly,then represents the physical design of an alpha magnet used in Beijing Free Electron Laser.The measured distribution of field gradient of the alpha magnet is reported.The field region with well distribution of │ΔG/G│<1.5% is from 0 to 13.3cm.The simulation and beam test proved that this magnet meets the requirement of the microwave electron gun.
Quantum Tensor Double and Realization of Quantum Groups
WU Ke, GUO Han-Ying
1993, 17(9): 796-802.
We propose the conception of quantum tensor-product double whereupon we show a simple and explicit relation between a given quantum group and its quantum algebra.
The Motion of an Isolated Gas Group in Expanding Universe
1993, 17(9): 803-806.
The contraction of an isolated gas group in the expanding universe has been discussed.It is found that in addition to the contracted conditions of the statical isolated gas group,the initial gas group is straticulate statistical uniform and the initial radius is larger than a critical value D-1r,the contracted conditions of expanding case also include that the Hubble constant H is smaller than a constant Dt.
One Problem in the Skyrme Model and its Simple Discussion
LI Tie-Zhong
1993, 17(9): 807-810.
This paper has suggested and answered one problem that has used an example of two Higgs doublets.That is due solely to the existence of a pseudoscalar triplet with a Lagrangian of the Skyrme form,then it shall be certainly to existe other type of Skrmions.
Vertex Correction and Phase Structure in (2+1) Dimensional Chiral Gross-Neveu Model
SHEN Kun, QIU Zhong-Ping
1993, 17(9): 811-815.
In 1/N order vertex and fermion mass corrections are calculated in (2+1)dimensional chiral Gross-Neveu model.In terms of the fermion mass spectrum,derived from chiral Ward-Takahashi identities,the phase structure in 1/N order is discussed.It turns out that chiral W-T identities with composite fields are a powerful method to investigate chiral symmetry breaking and higher order corrections.
Color Screening Effect and N-N Scattering
SHEN Xiao-Yan, SHEN Peng-Nian, YU You-Wen, ZHANG Zong-Ye
1993, 17(9): 816-821.
The N-N interaction is studied in terms of the color confinement potential which has the color screening effect.It is shown that by substituting this confinement potential for that of the linear or quadratic type,the problem of the long-tailed color Van de Waals force is solved,and a part of the medium-range attractive force of the N-N interaction obtained.
The Cluster Effect of The Semi-Inclusive Single-Particle Rapidity Distribution
1993, 17(9): 822-828.
In this paper,the theory of the minimum relative information entropy (MRIE) is applied to deduce the semi-inclusive single-particle rapidity distribution of final states of h-h produced in high energy collision.It is found that the cluster effect leads to centre deviate of the curve peaks of rapidity distribution,and the lower the multiplicity is,the more notable the cluster effect becomes.
Antiproton-Nucleus Elastic Scattering at Intermediate Energies
LI Yang-Guo
1993, 17(9): 829-834.
Using the experimental pN amplitudes and multiple scattering theory,we obtained the antiproton optical potential at incident energies from 180 to 1800MeV under the impulse approximation.It is found that the imaginary parts of the optical potential strengths are nearly constant between 120 to 140MeV.By using these optical potentials,We have the calculation results of the elastic scattering differential cross sections from the closed shell nuclei 12C,26O,40Ca and 208pb for five kinetic energies ranging from 180 to 1800MeV.At 180MeV,the experimental data are fitted very well,and the theoretical results at higher energies are predicted.
Mathematical Description of the Process from Initial State to Quasi-Stationary State
GU Jian-Zhong, LING Yin-Sheng
1993, 17(9): 835-838.
The process from initial state to quasi-stationary state is described by using the Fokker-Planck equation in bounded region with inhomogeneous boundary condition.The non-zero fission rate is obtained in the stationary limit for all nuclear temperature cases.
The Soft Dipole Resonance Extremely Neutron Rich Nucleus 11Li
CAI Yan-Huang
1993, 17(9): 839-844.
Giant dipole resonances (GDR) in nucleus 11Li have been studied within a microscopic Vlasov approach.A quite fair agreement with the experimental value is found.The results for both normal and soft modes are very sensitive to the spin-orbit coupling in mean field,while the soft mode is quite dependent on the extension of neutron halo in 11Li.The effects of separation energy of one neutron are also discussed.
QIU Zhi-Hong, CHEN Chi-Qing, WANG Yan-Sen, CHEN Jian-Xin, HUANG Fa-Yang
1993, 17(9): 845-850.
In this paper some effective non-local separable potentials for the interactions between neutron and α are suggested and examined in n-α scattering problem.With those potentials the analytic expressions of the S1/2,P1/2,P3/2 wave phase shifts are obtained.It makes easy to calculate the differential cross sections and polarizations of the scattered neutrons in arbitrary incident energy.Our results are in good agreement with the experiments at neutron energies below 20MeV.
The Moment of Inertia and Energy Spectrum for IBM Intrinsic Ground-State Single Phonon and Double Phonon Excited-States
ZHU Jian-Yang
1993, 17(9): 851-860.
The IBM intrinsic ground-state,single phonon and double phonon excited-states are given,where the double phonon states are different linear combinations of single phonon states.The Hamiltonian is defined as both SU(3) limit and pairing interaction.Using cranking theory,the moment of inertia and energy spectrum for these states are calculated,and rational analytical expressions obtained.As an example,the rationality of these results is also discussed for 168Er.
Improvement of the Parton Evolution Model in the Small x Region
YU Ming-Jian, SHEN Jian-Ping, LI Guang-Lie
1993, 17(9): 861-864.
In this paper,the parton evolution model is improved by using the modified Alteralli-Parisi equation which can describe the nuclear shadowing and anti-shadowing effects in the small x region.Within the theoretical framework of the improved parton evolution model,the unified description of the EMC effect,and nuclear shadowing and antishadowing effects is given without introducing the nuclear shadowing factor.