1986 Vol. 10, No. 1
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The exploring results of the possibility on detecting cosmic ray particles by acoustic way are reported. It shows that the ultrasonic background noise is very complicated and there are some individual and transient ultrasonic signals in the natural wide water. The mechanism producing these signals may be the sound radiation of the microbubbles in water. There is no evidence for the possible correlation between these signals and cosmic ray particles. The threshold energy of acoustic detection of EAS core is above 3﹒1016eV at sealevel and the threshold energy of acoustic detection of the local showers produced by cosmic ray particles is above 1014eV
By means of the surface Lagrangian and gauge invariant charge current, we make a detailed discussion to the physical meaning of each quantity in the boundary condition of the dyon-fermion dynamics; It is shown that adding the surface Lagrangian to the system is equivalent to selecting suitable boundary condition; By gauge trans-forming the Lagrangian by a charge generator, We get a corresponding U(1) charge current density which is both gauge invariant and spherosymmetrical. Ause of the canonical method and a careful treatment of surface terms show that the S-wave Hamiltonian given by Yamagishi requires amendment by a surface energy term.
The plasma effects of gauge theories are investigated and the one-loop contributions to self-energy part of the photon at T≠0 and μ≠0 are calculated. It is shown that only electric fields give photon an effective mass, but magnetic fields don's contribute.
The relation between the saddle point approximation and the action variational method in the lattice gauge field theory is discussed. It is expounded that in the thermodynamical limit by using a trial action composed of mean fields, the variational approach leads to the results as well as the higher order corrections obtained in the saddle point approximation. It is also pointed out that order by order corrections to the variational approach can be worked out systematically in an improved variational approach.
In this paper, the quark-antiquark one gluon exchange potential corresponding to the annihilation channels is calculated to the order of p2/m2 by means of Fierz reordering transformation. The nucleon-antinucleon effective potential obtained from one gluon exchange potential has a strong attraction at a short distance as expected in the meson-exchange theory.
By means of the Cloudy Bag Model (CBM), the contributions of pion field to nucleon-nucleon potential are calculated. It is shown that the results given by CBM are in good agreement with One-Pion-Exchange-Potential (OPEP) at large distance. Futhermore, in order to take into account the contributions of vector meson to nuclear force, we extend the CBM to include the vector meson and quark-antiquark-vector meson interaction. Using the Extended Cloudy Bag Model (ECBM) and Breit-Fermi equation of two nucleon system, through Foldy-Wouthuysen transformation, we get the nucleon-nucleon interaction which is in good agreement with naive One-Vector-Meson-Exchange-Potential (OVEP) in nonrelativistic limit, but effects of nucleon structure to nuclear force (form factor) are given.
Based on the two-chain model by A.Capella et al. the rapidity distributions of the multiplicity in high energy heavy-ion collisions, especially in head-on collisions, are discussed. The energy density at the center region in head-on collisions is estimated for different incident energies and different heavy ions. It is shown that the condition of the phase transition to the quark-gluon plasma can be realized in heavy-ion collisions at several tens of GeV.
The α-particles induced by 84.5MeV and 62 MeV 16O on 27Al are measured using ΔE-E semiconductor telescope. The energy spectra, the angular distributions, the contour plot of d2σ/dE﹒dΩ in the E-θ plane of the emitted α particles and the variation of the nuclear temperature with the emission angles are obtained. The mechanism of the direct α particles is discussed.
The energy spectra and angular distributions of Li, Be, B particles emitted from the 12C+112Sn and 12C+124Sn reactions at EL=70.0MeV are measured. The angular distributions of the Li, Be, and B particles are found to be peaked around the grazing angle, without any forward peaked component.
The experimental results also showed that the cross section for emission is larger in 12C+112Sn reaction than that in 12C+124Sn reaction, in contrast with the cross sections for Li, Be and B emissions. The indicates the effect of the neutron number of the target nucleus on the emission probability.
Branching formulas for SO(n) SO(n－1) tensor representations are given from the branching rules for SO(n) SO(n－1) which described in F.D.Murnaghan's. Furthermore, these formulas are extended to the spinor representations by using the method of kronecker products. In this way a pair of complete branching formulas for SO(n) SO(n－1) is give in this paper.
A concept of the quasi-composite system in the process of the pre-equilibrium emission is presented in this paper. On the basis of the principle of detailed balance, the existence of the factor, [γβω(πβ, 0,νβ, 0, E—U)/gπ,ν, has been proved with an account of the distinguishability between protons and neutrons. A formula for the rate of the complex particle emission in the pre-equilibrium process there by can be obtained. The theoretical calculation results fit the experimental data quite well, especially in the high energy part of the energy spectrum the agreement are much better than ever before.
Based on the experimental data of even-even nuclei in rare earth region, a further study on the interplay between subshells of two kinds of nucleons has been carried out. Emphasis is placed on the characteristice and N, I dependence of Z=64 subshell. Theoretical explanation is given in terms of the Nilsson diagram and a simplified calculation of n-p interactions.
The rotation-vibration spectra of nuclear molecule 12C+12C is chassified by the irreducible representations of group U(5). It is shown that the symmetry of rotation-vibration levels of nuclear molecule 12C+12C are discribed by means of dynamical symmetry U(5)U(4)O(4)O(3).
It is reported that the dependence of BGO light output on treatment of the surfaces of BGO crystal has been tested. The results indicate that the light output of BGO is larger when the coupling surface of BGO is more roughenned, and the other five surfaces are optically polished and wrapped with white paper.
The evolution of mean field of the two-center shell model was discussed according to full deformation process for symmetric fission and a unified description of both deformation and transfer processes was proposed.
Operating the drift chamber with the gas mixture of Ar+CH4, some performances of the drift chamber such as the pulse heights, the energy resolutions, the counting rates and the thresholds of the counting rate plateau have been measured under the different components of the nitrogen, oxygen and air in the gas mixture respectively. The permeability of different materials which used to make the gas pipeline have also been compared.
Using the renormalized quark mass m(g) obtained by fixing the ρ meson mass, we calculate the masses of the baryon states as a function of 1/g2 in lattice gauge theory with fermions by variational method. The results are in agreement with experimental values in the range of 1/g2 between 0.1 to 0.9.
A newly developed multipole permanent magnet structure is suggested. In this structure, the required multipole field can be formed by gradually varing the depth of the permanent magnet pieces. 2-dimensional space expression of the magnet field of this structure is also given.
Formulae for the meson exchange are deduced by using the spherical wave expansion in the nonrelativistic approximation. They will be convenient for calculating the corrections to the nuclear electromagnetic matrix elements of the meson exchange current operator.
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