1995 Vol. 19, No. S1
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Excited states of 117Xe were populated via the reaction 90Mo(28Si,2pn) at beam energy 115 MeV. The emitted prompt γ-rays were measured by using in beam γ-ray experimental techniques. Five bands of 117Xe have been identified, two of them are observed for the first time, and the three known bands are extended to higher spins.
The theoretical results of the atmospheric Cherenkov image of a muon on the focal plane of a reflector are given under the ideal conditions. The application to calibrate second-generation atmospheric Cherenkov imaging telescope is introduced briefly.
The splitting of hot nuclei into three massive fragments is analyzed by using a minimization procedure of difference between relative velocity and Coulomb repulsive velocity. It is utilized in 40Ar+209Bi, 197Au, l59Tb reactions at 25 MeV/u. The kinematics of ternary fragments emitted from excited nuclei with 3 MeV/u excitation energy produced by central collisions are presented. It is shown that the ternary fragments originate from two successive independent binary splitting. This result is also supported by the fact that experimental angular distributions of ternary fragments are nicely reproduced by sequential decays.
Based on the three-fireball model and the picture of hadronic resonance decays, the transverse momentum and pseudorapidity distributions of negative particles in relativistic heavy ion collisions are obtained and compared with the experimental results of 200 and 60 GeV/N 16O-Au interactions.
The boson resonance state X is produced along with f0(975) in the J/ψ hadronic decay process. If the X particle decays into a pair of pseudoscalar mesons its spin-parity is JPC=(odd)--. The helicity formalism of angular distribution of the process is presented. How to discriminate 1-- meson from 3-- meson for the X particle is discussed. We think that the X1(1573) which has been observed in the four prong channel (K+K-π+π-) and in company with f0(975)(→π+π-) by BES collaboration may be a new resonance state.
The p+p( )→p+J/ψ(γ)+X processes for energies ranging from ISR to SSC are discussed. Assuming that the structure of the Pomeron (P) is dominated by gluons with behavior of l/x at small x, the cross section for the above hard diffractive processes taking into account two main sub-diagrams and the cross section for "background" Drell-Yan processes are calculated in the lowest order of QCD. In contrast to the background cross section, which increases with InS, the diffractive hard cross section increases with (InS)2, hence the latter would be far larger than the former at TeV energies. It is shown that this property is universal for other hard diffractive processes. This would provide a new method for detecting physical particles at super-high energies by choosing suitable hard diffractive processed, provided that our above assumption of the Pomeron is correct.
The three-step two-body decay process of J/ψ, J/ψ→V+X, X→P1+Y, Y→P2+P3 is discussed by using the generalized moment analysis method. The spin, parity of the boson resonance X and the ratios of helicity amplitudes of the process can be determined in terms of the measurement of the corresponding moments except for very special cases.
The hard double diffractive production processes p+p( )→p+p( )+J/ψ(γ)+X at high energies are discussed. Under the assumption that gluon distribution with a behavior of l/x at small x in Pomeron is dominant, the dependence of cross section on energy √ is calculated. Comparisons with single diffractive hard process and corresponding non-diffractive Drell-Yang process are made. The present results show that the hard double diffractive processes are similar to single diffractive process, i.e., at extra-high energies the cross section basically increases in a manner of (In S)2. The importance of this discovery for experiments is also pointed out.
A Monte Carlo study for the one-dimensional quantum X-Y model by cluster algorithm is presented. For chains of L=32, 64 and 128 at βJ=1.0-10.0 temperature region, the dynamic properties are analyzed carefully and the corresponding thermodynamic quantities are computed. This method many be developed to apply to the lattice fermions systems.
The phase diagram of the lattice system of the SU(2) gauge field coupled with the fixed length Higgs field in the fundamental representation has been calculated analytically to the fourth order of the cumulant expansion. The variational parameters have been determined by scanning method. The obtained phase diagram is in fine agreement with the Monte Carlo result. The calculation also has been made for the Polyakov line <L> of the SU(2) Higgs and the pure SU(2) models at finite temperature (Nτ=1). The best (up to now) approximate analytical result βc for the pure SU(2) model is obtained.
The multiparticle Bose correlations of bosons emitted from dispersed thermal droplets of quark-gluon plasma are simulated by Monte Carlo. Multiparticle Bose correlations can offer more sensitivity to probe the granularity of the Boson-emitting source than two-particle Bose correlations. A promising signal of the existence of a mixed phase of quark-gluon plasma and hadronic gas can be obtained from multiparticle observable.
Starting from the shell model configuration and effective nucleon-nucleon interaction, a microscopic approach is applied to study the high-spin states of the isotopes 126Ba, 128Ba and 130Ba. The low-lying states and the band built upon aligned h11/2 proton pair configurations are considered. Energy levels and backbendings are well reproduced. For the yrast band, the dependence of the strength of interband interaction on coupling operator is discussed.
A comparison of two different nuclear structure models is made through 12C+12C scatterings. The comparison shows that the a-particle model of 12C gives the better results.
The transverse energy dependence of the yield of charmonium production relative to muon pairs in the mass continuum region in relativistic heavy ion collisions is analyzed based on the geometrical model and the absorption mechanism. Our results fit the data very well. It is shown that the nuclear effect is important in explaining the charmonium suppression.
The collision dynamic and the multifragmentation mechanism of the intermediate energy heavy ion have been studied by means of improved quantum molecular dynamics (IQMD) via studying dynamical observables which identify dynamical properties of the intermediate energy heavy ion collisions, such as the time development of the transverse momentum, collision number, density of nuclear matter and thermalization. At the same time, the dynamical ingredients governing the collision dynamics of heavy ion collisions, such as the equation of state, momentum dependent interaction and medium effect, have been analyzed and discussed.
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