1993 Vol. 17, No. 5

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The Monte Carlo Simulation for the Performance of the Yangbajing EAS Array,Tibet
1993, 17(5): 385-390.
An analysis of the performance of the Yangbajing EAS array,Tibet,has been done with the Monte Carlo simulation in this paper.Selection criteria on EAS events have been defined.The accuracy of EAS core position determination is 3.4m.The angular resolution of primary particle arrival direction is better than 1.1 degree.The energy response function of the array has been given,i.e. lg(E0)=lg(0.45ΣNi)±0.226,where E0(TeV) is the primary energy of the incident particle,ΣNi is the sum of detected particle number on FT detectors.
The Calibration of β-Scintillation Energy Spectrometer Using Monoenergetic γ-Rays
PAN Qiang-Yan, XU Shu-Wei, YUAN Shuang-Gui, ZHANG Xue-Qian
1993, 17(5): 391-395.
In this paper,a simple,convenient,precise and practical method for the calibration of β-scintillation energy spectrometer is introduced.the β-scintillation energy spectrometer is calibrated precisely by using four sources of 22Na,137Cs,54Mn and 207Bi.The half high points of the response curve of the spectrometer on the right hand side of the Comption peaks are chosen as the energy calibration points.According to this calibration result,the β-energy spectrum of 90Sr-90Y source is analysed.Its end-point energy is 2.298±0.90MeV.
Pseudorapidity Gap Length Distributions in pp Collisions at 400GeV/c
WANG Shao-Shun, ZHANG Jie, XIAO Chen-Guo, YE Yun-Xiu, LUO Qi, CHENG Zheng-Dong, XIONG Wei-Jun, YANG Chun
1993, 17(5): 396-402.
The distributions of the pseudorapidity gap length between two particles,which included (K-1) particles between them,and many-particle pseudorapidity correlation functions have been calculated by using the experimental data of the charged particles pseudorapidity distributions produced in 400GeV/c pp collisions.The Monte Carlo simulations for the experimental data have been mede based on a cluster model.The average cluster size has been estimated.
Beam Centre Monitoring of 4W1A Beam Line at BEPC and The Observation of XRF Spectra Signal to Noise Ratio
HONG Rong, WU Ying-Rong, CHAO Zhi-Yu, XIAO Yanan, LI Xue-Jun
1993, 17(5): 403-406.
The vertical distribution curves for incident and scattering intensity from the wiggler white beam line 4W1A of BEPC have been measured.The signal to noise ratio observation of the XRF spectra at beam centre and the maximum position of the scattering curve have been made.
BFV Quantization of the Bosonized Schwinger Model
MIAO Yan-Gang
1993, 17(5): 407-411.
The bosonized Schwinger model is quantized by using the Batalin-Fradkin-Vilkovisky(BFV) formalism.The quantized versions of the model, which are equivalent to those obtained in terms of the path-integral and Dirac's method,are derived through appropriate choiees of the Fermi function.
A New Symmetric Transformation of the Static Axizlly Symmetric SDYM Fields
HAO San-Ru
1993, 17(5): 412-416.
By means of the solutions of the Lax pair of the static axially symmetric self-dual Yang-Mills (SDYM) fields,a new symmetric transformation of the static axially symmetric SDYM fields is constructed.
Yukawa Potential at Finite Temperature and Finite Density
QIAN Zhi-Xin, ZHONG Wan-Heng, SU Ru-Keng
1993, 17(5): 417-422.
By means of the real time Green's function method,the yukawa potential is extended to finite temperature and finite density.It is found that the effective mass of sigma meson will decrease as the temperature and/or density increase.The results given by the real time Green's function method and the imaginary time Green's function method are compared.
Irreducible Representation of Quantum Algebra SUq(4)
YANG Ya-Ping, YU Zu-Rong
1993, 17(5): 423-430.
Irreducible representations and a recurrent formula to calculate reduced matrix elements has been obtained through a tensor-like method.Some of the reduced matrix elements are tabulated.
From Integrability to Conformal Symmetry: Bosonic Superconformal Toda Theories
1993, 17(5): 431-443.
In this paper we study the new conformal integrable models obtained from conformal reductions of WZNW theory associated with second order constraints,these models are called bosonic superconformal Toda models due to their conformal spectra and their resemblance to the usual Toda theories.From the reduction procedure we get the equations of motion and the linearized Lax equations for such systems in a generic gradation of the underlying Lie algebra.Then,in the special case of principal gradation,we derive the classical r-matrix,fundamental Poisson relation,exchange algebra of the chiral operators and find out the classical vertex operators.The result shows that our model may play a similar role with respect to the ordinary Toda theories in which one may obtainvarious conformal properties of the model from its integrability.
Instantaneous Probability Distribution and Nonequilibrium Entropy of Nuclear Exciton States
PAN Zhong-Cheng, JIANG Shao-Zhou, GAO Liang-Jun, LONG Sheng-Dong
1993, 17(5): 444-447.
In this paper the Laplace transformations and the continued fraction method are used to handle the problem of the probability distribution in the model nuclear exciton.The algebraic expressions of all the transformation matrix elements are given,and the excited state probability distribution and instantaneous entropy are calculated.
Study of Antihydrogen Atom Formation in Collisions of Antiprotons with Positronium
CHENG Zi-Tao, QIAN Qing, FU Yun-Chang, CHEN Xue-Jun
1993, 17(5): 448-454.
Enhancement of K++ Ratio in High-Energy Proton-Nucleus and Nucleus-Nucleus Collisions Due to the Secondary Collisions
1993, 17(5): 455-461.
The pion meson secondary collisions with surrounding nucleons in the nucleus can change the K++ ratio.We calculate this effect in proton-nucleus-nucleus collisions by the Glauber model and find that the final state interactions are important.
K+-Nucleus Scattering and Nonlinear Densitydependent Correction
MIN De-Fen, NING Ping-Zhi, LI Qing-Run, JINAG Shao-Zhou, WU Xiu-Wen, CHEN Xia-Xian
1993, 17(5): 462-468.
Microscopic calculations of the K+ elastic scattering on 4He,12C,40Ca and 120Sn at 800MeV/c are performed,in which non-linear density-dependent corrections are included.The influence of the corrections in K+ scattering on different nuclei are discussed.
Is the Eikonal Approximation Certainly Bad at Larger Angles?
YANG Yong-Xu, LI Qing-Run
1993, 17(5): 469-471.
The eikonal approximation is considered to be valid only for high energy and smaller angles.It is generally accepted that the eikonal approximation is certainly bad at larger angles.We show that the above view is a customary misunder-standing.
The Color Screening Effect on Heavy Quarkonia
DONG Yu-Bing, YU You-Wen, WANG Ying-Cai
1993, 17(5): 472-475.
In this paper,by taking the confining potential with the color screening effect as a color confinement between quark and antiquark,the effect on heavy quarkonia (cc and bb) is studied.It shows that the effect may give different predictions for orbital angular momentum of high excited energy levels of ψ(cc),and make improvement in the widths of leptonic decay mode.
Influence of Finite Collision Time on Energy Density in Relativistic Heavy Ion Collisions
ZHAO Wei-Qin
1993, 17(5): 476-480.
The space-time development of the energy density in relativistic heavy ion collisions is analyzed based on Monte Carlo code ODIN.The result shows that the actually reached energy density is much lower than Bjorken's estimation due to the finite collision time.