1989 Vol. 13, No. 9

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Review
POSITRON ANNIHILATION STUDY OF PHASE TRANSITION IN HIGH-TEMPERATURE SUPERCONDUCTOR Y-Ba-Cu-O
ZHANG Duan-Ming, LI Guo-Yuan, WANG Jian-An, HE Yuan-Jin
1989, 13(9): 769-771.
Abstract:
The resistance,positron lifetime spectra and the Doppler broadening energy spectra of high Tc supercondoctor Y-Ba-Cu-O are measured simultaneously near the phase transition temperature.It is shown that the critical temperature of the material is about 90°K,and the positron annihilation mean lifetime m as well as the Doppler broadening parmeters H and S are in a state of irregular vibration within the phase transition region.This pheuomenon may probaley relate to the instability of the crystal structure,and seems supporting the uperconducting mechanism in which the bipolaron theory a major role.
CALCULATION AND EVENTS GENERATION OF Bhabha SCATTERING AT LEP/SLC ENERGY
YE Jing-Bo, MA Wen-Gan, ZHANG Zi-Ping, XU Zi-Zong, DAI Qing-Hai
1989, 13(9): 772-780.
Abstract:
We give here the one loop results of the numerical calculation and events generation of Bhabha scattering at LEP/SLC energy.EM radiative correction and hard collinear photon effect have been taken into consideration.
RESULTS OF COSMIC RAY TESTS WITH THE BES MAIN DRIBT CHAMBER
MA Ji-Mao, MAO Hui-Shun, BAI Jing-Zhi, XIE Pei-Pei, YAN Jie, WANG Yao-Hui, LIU Rong-Guang, SONG Xiao-Fei, WU Zhen-Dong, FAN Qun
1989, 13(9): 781-788.
Abstract:
The structure of the BES main drift chamber and arrangement of cosmic ray tests have been described briefly,The main test results of the chamber performance have been given.There are S-T relations with good linearity in the cells.The spatial resolution of 210—240μm has been obtained for single wire.The energy resolution corresponding to 40 samples in the chamber is 8.7%.
ON THE CHOICE OF THE TRIAL ACTION IN VARIATIONAL CUMULANT EXPANSION APPROACH ON LATTICE
WU Ji-Min
1989, 13(9): 789-795.
Abstract:
We take lattice φ4 theory as an example to illustrate one of the principles for the choice of the trial action in variational-cumulant expansion approach on lattice.
EFFECT OF NUCLEAR EFFECT ON THE NUCLEON STRUCTURE FUNCTIONS UPON HIGH PT DIRECT PHOTON PRODUCTIONS IN p-Al COLISIONS
CHEN Ying-Yang, HE Zhen-Min, HOU Yun-Zhi
1989, 13(9): 796-802.
Abstract:
Using the empirical formula on R(x)=FN2(D) proposed by the authors and generalizing the method used in calculating the processes p+p(p)—γ+X,the differential cross sections and the total cross sections for high pT direct photon productions in p-Al collisions are calculated,and some new predictions are obtained.These theoretical results are to be checked by future experiments.
BARYON PRODUCTION IN e+e ANNIHILATION
LIU Xi-Ming
1989, 13(9): 803-807.
Abstract:
It is poined out that the relative weight between (3/2)+ and (1/2)+ baryons has no effect on the yield of long-lived baryons in final states,but changes the yield of (3/2)+ baryons considerably.By analysing the experimental data we show a very strong suppression factor of (3/2)+ baryons of the order 0.3, and as a result the yield of the final state baryons and their ratio all agree with experiment.
INVESTIGATION OF THE HIGH ENERGY LIMIT IN HADRON-HADRON COLLISION USING MEM
WU Yuan-Fang, LIU Lian-Shou
1989, 13(9): 808-813.
Abstract:
Using the Maximum Entropy Method (MEM),we investigatied the high energy limit in hadron-hadron collisions.Different kinds of entropy are defined and the role of physical constraints in maximizing the entropy are emphasized.Definite prediction for the average multiplicity in high energy limit and the interpolation between this limit and the existing data are obtained.
A PROBABLE EXPLANATION OF THE 5He OVERBINDING PROBLEM
LIU Ji-Feng, SHEN Jian-Ping, LI Guang-Lie
1989, 13(9): 814-821.
Abstract:
In this paper,based upon analysing the various factors which might cause the overbinding of 5He,we make a proper adjustment for the wave function of the core nucleus 4He.With the adjusted core wave function and various Λ-N interactions,we calculate the Λ-hyperon binding energy BΛ(5He) of the 5He ground state and obtain a reasonable agreement between the theoretical and experimental values of BΛ(5He).Thus, the 5He overbinding problem could be explained.
EFFECT OF THE PAULI EXCLUSION PRINCIPLE IN MULTI-PARTICLE AND HOLE STATE DENSITIES
ZHANG Jing-Shang, YANG Xian-Jun
1989, 13(9): 822-832.
Abstract:
A method to calculate the effect of the Pauli exclusion principle in multiparticle and hole state densities has been proposed.As the physical application,the exact Pauli exclusion correlation values have been calculated in the equidistant spacing model.The exact Pauli exclusion correlation values are obviously larger than that used before,such as the kalbach's values.Correspondinyly the internal transition tates and equilibrium exciton number have been changed.
ON RELIABILITY OF THE LOCALLY HARMONIC APPROXIMATION METHOD FOR SOLVING THE FOKKERPLANCK EQUATION
SUN Zhe-Min, WU Xi-Zhen, FENG Ren-Fa, ZHUO Yi-Zhong, XING Jing-Ru, ZHANG Shu-Fa
1989, 13(9): 833-836.
Abstract:
By comparing the results calculated by the locally harmonic approximation methed and the numerical solution for the FOKKER-PLANCK equation with a nonlinear force,the reliability of the locally harmonic approximation has been examined and discussed in a considerably wide range of nuclear temperature and viscosity.
ELECTROMAGNETIC TRANSITIONS OF NUCLEI IN ANGULAR MOMENTUM PROJECTION HARTREE-FOCK METHOD
LIAO Ji-Zhi
1989, 13(9): 837-841.
Abstract:
In this paper the formula for the matrix elements of an one-body tensor operator of the many-particle system between two PDHF states is given.The B(E2) values of the electric quadruple Gamma transitions between the low-lying states of even-even titanium nuclei are calculated,and the evidences exhibiting the band intersection in the yeast are found.
THE STUDY OF THE STRUCTURE OF 10Be HYPERNUCLEUS
WANG Xi-Cang
1989, 13(9): 842-848.
Abstract:
The Structure of hypernucleus 10Be is studied by using 9Be+Λ two cluster model.Using the transition density matrix of 9Be,the folding potential of ΛN interaction is obtained.Taking into account the glue-like role of Λ-hyperon in the hypernucleus,a contraction factor S is introduced into the density matrix of 9Be.The eigenvalues EI of 10Be are obtained by solving the channelcoupled equations.
GROUP CHAIN CHECK ON THE PROTON-NEUTRON INTERACTING BOSON MODEL COMPUTER CODE NPBOS
LONG Gui-Lu, SUN Hong-Zhou
1989, 13(9): 849-855.
Abstract:
In view of the proton boson and neutron boson coupling,all possible dynamical symmetries in the proton-neutron interacting boson model are discussed.The symmetries are found to be in four types,of which some are newly discovered.The commonly used IBM2 computer code NPBOS is checked through group chain method.It is found that most NPBOS calculations are correct,except in cases where Qπ Qπ and Qv Qv is included in the Hamiltonian.Using NPBOS,150Sm and 152Sm are studied.
INTERACTIONS OF NUCLEI AND LASER (2) ——LASER ENHANCED EFFECTIVE NEUTRON WIDTH FOR NUCLEAR RESONANCE
HUO Yu-Kun, PAN Zheng-Ying
1989, 13(9): 856-859.
Abstract:
This paper investigates laser-induced meutron radiative capture reaction.There exist great discrepancies between the existing theoretical and experimental studies on this subject.From Einstein's general theory about emission and absorption of photon,a formula to calculate the laser enhanced neutron width for nuclear resonance has been given with a feature that the width is expressed in terms of model-independent measurable parameters.The measured widths have been analysed and compared with the calculated.The possibility to observe the effect in the near future has also been discussed.
EXACT CALCULATION OF STRING TENSIONS OF LATTICE SCHWINGER MODELS
ZHENG Bo
1989, 13(9): 860-864.
Abstract:
In this paper string tensions of both the modified Naive and Susskind lattice Schwinger models which have the solvable exact ground states are calculated exaqctly.The linear potential between quark and antiquark infinitely seperated is derived for both Naive and Susskind lattice Schwinger models.No phase transition occurs when a tends to zero and this coincides with the continum theory.