1990 Vol. 14, No. 12
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The role and selection procedure of the trigger system of BES are introduced The physical considerations and construction of its various parts are described respectively.
In this paper the distributions of the electron density,the electron temperature and the drift angular velocity in the axisymmetrical self-sustaining magnetically confined electron clouds are studied.The influence of the ions produced by ionization of the electron cloud is discussed.The scaling relations and the numerical computational method of the physical quantities of the electron clouds and the electromagnetic fields are introduced.
We use the requirement of the chirality and complementarity in grand unified preon models to search for possible models.The general requirements to SU(N) grand unified preon models are:1) satisfying the requirement of the chirality;2) satisfying complementarity;3) giving at least three families of quarks and leptons.We mainly discuss the requirement of the chirality.We find that the model which satisfies the above three require ments is SU(10) grand unified preon model and we discuss this model in detail.
The finite temperature real time Green's function method with normal pair cutoff and abnormal pair cutoff approximation is applied to derive the equation of state and the energy gap equation for nuclear matter with the Gogny D1 effective interaction.The critical temperature for liquid-gas phase transition and for superconducting phase transition are found to be 14.8MeV and 0.2MeV respectively.The energy gap is determined by the finite range part of the Gogny D1 interaction only.
A systematic derivation of the general formulas used in the EFV (short for Excited few determinants VAMPIR) method for the microscopic description of the nucleor structure is presented.
The formation of η-meson-nucleus bound states is investigated,using a standard Green's function of many-body problems.Within physically reasonable range of the parameters (coupling constants and harmonic oscillator potentials),we find that the η-16O bound state is indeed possible and depends crucially on the ηNN*(1/2,1－/2) interaction being attractive.Our results indicate that the widths Γ are larger than the η binding energy in 16Oη,which would make the observation of such states defficult.
The 153Dy level structure has been investigated through in-beam γ-ray spectroscopy experiment.The reaction 122Sn(36s,5n) was studied at beam energy 165MeV.The highest spin was 81/2.Above I=47/2 isomer,extremely complicated single-particle character was shown.Nuclear shape changes with N and I in the neutron-deficient Dy nuclei were discussed.
Thick-target recoil ranges of the residues from the interaction of 93Nb with 46MeV/A 12C ions have been measured by off-line γ-ray spectroscopy.From these data the maximum linear momentum transfer and the mean linear momentum transfer were obtained.A comparison with other results indicates that the maximum linear momentum transfer,corresponding to central collisions is independent of the target mass mumbers for light and intermediatmass targets.However the mean linear momentum transfer shows a strong dependence of the projectile-target asymmetry.
The cross sections for 62Ni(n,α)59Fe have been measured by using the activation method relative to the cross sections of 27Al(n,α)24Na in the neutron energy range of 13.6—14.8MeV.The values of 17.4±1.1,19.5±1.5,21.9±1.9,22.4±1.6,25.4±1.4,26.1±1.1 and 26.0±1.1mb were obtained at the 13.64,13.79,14.00,14.05,14.33,14.60 and 14.80MeV neutron energies,respectively.The results are compared with the published and to be published data.The neutron energies were determined by the method of cross section ratios for the reactions 90Zr(n,2n)89m+gZr by 93Nb(n,2n)92mNb.
A light-particle multidetector system was built for heavy-ion reaction mechanism research at intermediate energies (10—100MeV/u).It is able to discriminate light particles (p,α etc.)and give the information about energy,position and multiplicity of light charged particles with 36 units,θ:5°—20°,φ0°—360°,every unit covers a solid angle of Δθ=5°,Δφ=30°.The result of a tentative measurement shows that satisfactory resolution for light particles can be obtained.
Using a model of relativistic quantum field theory (QHD-I) and Thomas-Fermi approximation,the formula of the effective radius R=R0A1/3 has been studied in the region of nuclear interaction force.It is found that the theoretical results are in agreement with experimental results of α partcle-nucleus scattering data.
The signature-dependence of B(M1)-values and dynamical quadrupole moments Q(1) and Q(2) after the band-crossing are investigated by meams of the extended particle-rotor model.The calculated values are in qualitative agreement with the measured data.It was noted that in 159Tm the γ-value is quite different before and after the band-crossing.
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