1995 Vol. 19, No. 1
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In this paper,the principle of primary vertex fitting of BES has been described. Some modifications to the original program are made and the vertex distributions for the experimental data of Run462—961 are presented.
The behaviour of prompt γ-ray emission in the cold fission of 252Cf was investigated experimentally using a four-parameter correlation technique. A twin gridded ionization chamber was employed to detect the fission signals and to determine the fragment emission angles, and a φ10cm×10cm NaI(T1) detector was used to record the γ-ray energies. The result shows that the angular distribution coefficient of γ-rays emitted in cold fission is twice as large as that in the normal fission.The fact that in the cold fission the number of γ-rays emitted from the light fragments is approximately three times as large as that from the heavy ones can not be explained satisfactorily so far.
The three-step two-body decay process of J/ψ,J/ψ→V+X,X→P1+ Y,Y→P2+P3 is discussed using the generalized moment analysis method. The spin, parity and the ratios of helicity amplitudes of boson resonance X can be determined in terms of the measurement of the corresponding moments except a very special case.
By comparing the results obtained using the same experimental data of CIAE but different theoretical formula fits it is pointed out that the negative value of mv2 is most likely stemmed from inaccuracy of the theoretical formula of the β-spectrum.
The double diffractive J/ψ, hard production processes is discussed. Assuming that Pomeron has parton distributions and dominated by gluons with behavior as 1/x when x is small, the energy dependance of the cross section, for above processes is calculated and compared with both the cross section of single diffractive hard scattering and of Drell-Yan processes . It is shown that the is similar with and increases as (lnS)2 at superhigh energies. It is emphasized that this character may provide a new method for detecting physical particles at energy ranges of SSC.
A Monte-Carlo study for the one-dimensional quantum X-Y model by cluster algorithm is presented. For lattices of L=32, 64 and 128 and at βJ=1.0-10.0 temperature region, the dynamical properties are analysed carefully and the corresponding thermodynamical quantities are computed. This method may be developed to apply for the lattice fermion systems.
Based on the geometrical model and absorption mechanism. transverse energy dependence of the yield of charmonium production relative to muon pairs in the mass continuum region in relativistic heavy ion collisions is analysed. Our results fit the data very well. It is shown that nuclear effect is important in explaining the charmonium suppression.
Using the modified QMD (MQMD), the intermediate-energy heavy ion collision dynamics and the multifragmentation mechanism are investigated. The dynamical ingredients governing the multifragmentation process and collision dynamics in heavy ion collisions are discussed.
A new effective interaction between a neutron and the 9Li core is introduced, and based on the n+n+9Li model, a variational calculation on the neutron rich nucleus 11Li is completed. The one-body density, formfactor and shapedensity are investigated, The RMS radius and the binding energy are also calculated and are in good agreement with the experimental data.
In the framework of shell model the structure properties of Pb nuclei (A=204,205,206) are calculated and stutied using MSDI and Kuo-Hening interaction as a residual interaction between the neutron holes. Overall comparison of the calculation results for MSDI and Kuo-Herling interaction shows that MSDI works well too in describing the properties of nuclei in Pb region. In addition the method for judging the TBME from. experimental data is also discussed.
The matching problem of lattice with transverse coupling has been discussed in this paper. The matching conditions and the related equations of the effective beam emittance are given.
This paper describes the new soft X-ray reflectometer with multilayer monochromator on beam line 3B1 of Beijing Synchrotron Radiation Facility (BSRF). The transmitted spectrum of aluminum filter and reflected spectrum of Nb/Si multilayer in soft X-ray region have been analysed with this reflectometer. The reflectivity of a Nb/Si multilayer manufactured in our group (41 layers, d = 13.45 and wavelength near 17.59um at 42 deg.) has been measured to be 32%.
The spin-orbit interactions between two quarks due to the one-gluon exchange,the confinement potential, the σ exchange of chiral field and the twogluon exchange are all considered in our calculation. As a consequence the spin-orbit splitting of 1P state in the baryon spectrum and the 3P2 phase shifts of the N-N scattering can be well explained simultaneously.
The hadronic decays ,and ωf2(1270) have been studied in a sample of 1.27 million produced.Measurements of their branching fractions are presented. While obeys the "14% rule" predicted by theory, →ωf2 (1270) is suppressed comparing with the corresponding decay. As a vector-tensor pair combination, the ωf2 mode is the first example of a non-vector-pseudoscalar decay of charmonium which violates the above mentioned rule.
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