## 1992 Vol. 16, No. S2

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**Abstract:**

^{57}Fe-Mössbauer spectra of GdBa

_{2}(Cu

_{1-x}Fe

_{x})

_{3}O

_{7-δ}(

*x*=0.005) are studied in a wide temperature range (1.4-700 K), and the valence states and surroundings of iron cations are analyzed. There are four sites for Fe:A,B, C and D. Fe(A), Fe(B) and Fe(C) occupy Cu(l) sites with different O-coordinations. Fe(D) is attributed to a Cu(2) site with only one definite O-surrounding. The Fe cations are identified as high spin 4+ at site B and 3+ at site D. Alignment of polycrystalline powder absorber in a magnetic field leads to small texture effects.

**Abstract:**

By using small Pb emulsion chambers placed at a camping site for a Qomolangma (Everest) mountaineering team with an altitude of 6500 m a.s.l.,the intensity of high energy cosmic ray hadrons was determined. By combining the data with those observed at Mt. Kanbala (5500 m a.s.l.) and the Yunnan Cosmic Ray Observatory (3200 m a.s.l.), the altitude variation of high energy cosmic ray hadrons was obtained.

**Abstract:**

The pseudorapidity distribution of charged particles produced in pp collisions at 400 GeV/

*c*was measured by using LEBC films. The two-particle pseudorapidity correlations at fixed multiplicity were studied. The experimental data were fitted with cluster model. It was found that the average cluster multiplicities as well as the cluster decay widths vary slightly with charged multiplicity.

**Abstract:**

A method for the measurement of the vacuum decay rate

*λ*

_{0}of orthopositronium is presented and the preliminary result is

*λ*

_{0}=7.034 ±0.013

*μ*s

^{-1}. The possibility of improving the experiment is discussed.

**Abstract:**

By using the theory of uniformization of Riemannian surface, we study the properties of the Liouville equation and its general solution on a Riemannian surface of genus

*g*>1. After obtaining Hamiltonian formalism in terms of free fields and calculating classical exchange matrices, we prove the classical integrability of Liouville system on high genus Riemannian surface.

**Abstract:**

With the theory of harmonic maps and the eight-dimensional Riemannian manifold, the completely integrable

*SU*(2) and

*SU*(3) self-dual Yang-mills source-free field equations are described. Sixteen independent Killing vector fields are determined, two transformation groups which map solutions into solutions are constructed, and conjecture on the complete integrability of systems by the inverse scattering method is formulated.

**Abstract:**

By using the Feigin-Fuch integral, we calculate the correlation function, operator product coefficient and crossing matrices of the nonunitary

*SU*(2) Wess-Zumino-Witten model. We also give the modular matrix from the fusion matrix and discuss the relations between the nonunitary

*SU*(2) WZW model and the unitary one.

**Abstract:**

Using new creation-annihilation operators constructed in this work, we are able to determine the eigenvalues and eigenfunctions of the hydrogen by the algebraic method, which is analogous to the well-known method for the harmonic oscillator.

**Abstract:**

An exact Goldstein solution of the Bethe-Salpeter equation for a vanishing total four-momentum in the ladder approximation of the free gluon exchange and the gloun condensating correction is discussed in detail. We find that the gluon condensate correction makes a pair of quark-antiquark more likely to form a bound state.

**Abstract:**

Using the free field representation, we calculate the

*r*-matrix and the classical exchange algebra for WZNW model under the periodic boundary condition, and discuss the quantum counterparts of the exchange algebra as well as the performance of the

*r*-matrix and the classical exchange algebra under Hamiltonian reductions.

**Abstract:**

Based on the Lurie model, a convenient scheme is constructed for calculating the equation of state approximately. The parametric equation of state is given in the Lurie model. The phase diagram of the model shows the existence of a critical point separating first order from second order chiral phase transition. A careful analysis of the isotherms of pressure versus net baryon number density suggests the existence of overheat and overcool metastable state and the coexistence of broken phase and normal phase.

**Abstract:**

The dynamical process of the heavy ion collision in the energy region from 10 to 100 MeV/

*A*is investigated by the quantum molecular dynamics model. According to the calculated mass distribution, the evolution of the mass and density distribution with respect to time is calculated. The reaction mechanism and its characteristics are predicted and compared with those obtained from the BUU model.

**Abstract:**

The high spin states of

^{68}Ge,

^{65}Ga and

^{67}Ga are studied in the in-beam gamma-ray spectroscopy experiment. The reaction

^{46}Ti (

^{25}Mg,

*x*p

*x*n) with the beam energy of 68 MeV is used. In

^{68}Ge, the multiplicity of band structures, crossing transitions among bands and a new band with possible big deformation are observed. The experimental results agree with the calculated result in the new microscopic model (EXCITED FED VAJVIPIR). In

^{65}Ga and

^{67}Ga, some band structures with strong collectivity are observed and the new level schemes are given.

**Abstract:**

Fluctuations of the produced particles in the final states of high energy collisions may be the breakthrough in the investigation of multiparticle dynamics. How to eliminate the statistical noise of the system is one of the most important problems. In this paper, the influence of the statistical noise on fractal structure is analyzed and a method for eliminating the statistical noise is proposed by using the Monte Carlo simulation based on a simple dynamical model.

**ISSN** 1674-1137 **CN** 11-5641/O4

Original research articles, Ietters and reviews Covering theory and experiments in the fieids of

- Particle physics
- Nuclear physics
- Particle and nuclear astrophysics
- Cosmology

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