1994 Vol. 18, No. 2
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The effect of surface diffuseness of neutron distribution on total reaction cross section σR is discussed based on coulomb－modified Glauber model． Considering a relation of surface diffuseness of neutron distribution with the neutron separation energy of nuclei， the large increasing of nuclear total reaction cross section for exotic nuclei (such as 6He, 8He, 11Li, 11Be) on 12C target can be reasonably explained.The total reaction cross section for a large number of stable nuclear systems can also be reproduced over an energy range beginning witb the coulomb barrier to a few GeV/nucleon.
In this paper,the results of two-proton interferometry obtained in the experiment of 46.7 MeV/u 12C+58Ni,115In,197Au have been discussed. The influnce of nuclear force, Couloumb force and Fermi statistics on the correlation function is discussed also. The source radius parameters ro obtained from the experiment increase withincreasing of the target nuclei mass. In the experiment, the p-p correlation function seems to have a strong dependencs on the sum energy of two correlated protons. The ro parameter decreases with increasing of the sum energy, indicating that the high energy protons are mainly from the nonequilibrium emission process.
The research results of a thin multiwire chamber operating with strongly quenching gas and its discharge mechanism are presented in this paper. It is indicated by experiments that high gas gain and fast time response could be achieved simultaneously because of operating in the saturated mode. The effect of space charges and the emergence and action of ionizing photons are essential factors in its discharge mechanism, but the latter factor is restrained by the strongly quenching gas.
On the basis of the research of the transformation groups in beam optics, some problems such as the periodic field focusing, beam batching, chromatic dispersion and aberration are discussed.
The Hamiltonian reductions of supersymmetric self-dual Yang-Mills theory are analysed. Under the left-right dual constant constraints, this theory is reduced to the four dimensional supersymmetric nonabelian Toda model. The corresponding actionand linear systems are also obtained as the result of Hamiltonian reductions. In the case of first order constraints under the principal gradation of the underlying Lie superalgebra, the reduced theory is shown to be the four dimensional supersymmetric Toda model. The reduction procedure apply to any Lie superalgebra without requiring a purely odd simple root system.
We present the pseudo-scalar solutions of the equal-time equation for the quarkantiquark bound states in QCD in the background fields. The kernel includes both of perturbative and nonpertubative interactions. The perturbative part is usual onegluon exchange, nonperturbative part comes from the contributions of the lowest order quark and gluon condensates. With the reasonable parameters, we obtain the mass spectrum in good agreement with the data.
In this paper, the removability of the topological term in the 1+1 dimension CP1 model is studied. The unitary transformation which removes the topological term in the CP1 model is obtained. The relation of the topological term to the a vacuum and geometric phase is found.
The target mass dependence, α，on the yield of charged particles as a function of pseudorapidity n has been investigated for p, 16O and 32S induced central collisions at 200A GeV. It is pointed out that α(η)≤0.4 if we only consider the simple linear superposition of nucleon-nucleon collisions. The experimental data α→1 in the target fragmentation region show the importance of nonlinear collective effect even at present incident energy. Our results from a hydrodynamical model can describe the target mlass dependence well for different projectiles in the whole rapidity ragion.
By means of the imaginary-time Green's function method in the finite-temperature field theory, the η-meson and nucleons interaction coupling constant, the effective mass of η-meson and the one η-meson exchange potential for the pseudoscalarcoupling at finite temperature are given. The results are compared with that given by the pseudovector coupling case.
The dynamics of linear momentum dissipation in the reaction of 50MeV/u 12C with 209Bi has been studied within the BUU approach. For the peripheral collision,deep inelastic reaction process similar to what observed at lower energy region seems to persist, indicating an important effect of the mean field. For the central collision, complete momentum transfer is inhibited from the preequilibrium particle emission. The predictions of BUU equation reasonablily agree with the experimental data.
Two examples are presented to show that the probability distributions of the probabilities, with which the particles fall into the corresponding rapidity intervals, are not sure to lead to the power law behaviour of the fractorial moments of the rapidity distribution, and hence are not a sufficient condition to get the intermittency behaviours.
In this paper, the time development of high energy heavy ion collision are described by the relativistic kinetic equation. The rapidity distribution of the final state particles under 200A GeV 16O and 32S particles beams are analysed in the central rapidity region. The various system relaxation time are determined.
By using the Chapman-Enskog method, we calculate the transport coefficients ofhadron matter in the central rapidity region for relativistic heavy-ion collions, and establish the corresponding viscous hydrodynamical equation. The numerical solution of the equation shows that viscous effects slow down the cooling of pion matter in the central rapidity region.
We calculate the effect of secondary collisions in the K+/π+ ratio by an eikonal approximation and find that the secondary collisions are important.
The distorted wave of antiproton is obtained by an optical potential derived from the multiple scattering theory In the framework of the distorted wave impulseapproximation, we discuss the antiproton-nucleus inelastic scattering at intermediate energies. The inelastic differential cross sections of 2+, 3- states at antiproton energies from 180 MeV to 1800 MeV are calculated. It is shown that DWIA fitted the experimented data quite well, and theoretical results of inelastic cross sections at higher energies are predicted.
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