1992 Vol. 16, No. 4
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Under the assumption of mixed primary cosmic ray composition and using a hadron-hadron interaction parametrization model to describe hadron-hadron nuclear interaction,the behavior of superhigh energy cosmic ray particles in the atmosphere is simulated,and the simulated results compared with experimental data of Mt.emulsion chamber in details.The influences from the mean transverse momentum value of secondary particles in fragmentation region on simulated results are discussed also in details.
In order to meet the needs of measuring high energy γ-rays produced in heavy ion reactions at intermediate energies,a large cylindrical BGO detector has been assembled by using China-made crystal and photomultiplier tube.This report presents the light collection method and the relative light yield of the crystal,and the energy and time resolution of the detector.A comparison was made about using defferent kinds of photomutiplier tubes.The possibility of applying detectors of this kind to heavy ion experiments has been discussed.
In this paper the axisymmetrical self-sustaining magnetically confined electron clouds are studied by means of the numerical computational method on the basis of the fluid theory.The electron density distribution,electric potential distribution,drift angular frequency and electron temperature can be calculated with a simplified method in which the near-equilibrium state approximation is necessary.The results are,in principle,in agreement with the experiments.
The motion of ions generated from the electron-atom ionization collisions in the self-sustaining magnetically confined electron cloud is studied.It is shown that the motion is chaotic.The method to determine the electric potential idstribution in the electron cloud by measurements of the ion current is discussed.
Based on the Waleck's models QHD-Ⅰ and QHD-Ⅱ describing the nucleon-nucleon interaction,the Boltzmann-Uehling-Uhlenbeck (BUU) equation,which is the time evolution of the nucleon distribution function including the Hartree and Fock self-energy terms as well as the Born collision term and its exchange term,has been derived by using the closed-time path Green's function technique and assuming that the Green's functions and the self-energy terms are slowly varying functions of the centre-of-mass coordinates.Our result shows that the BUU equation for proton and that for neutron are simultaneous each other.
By using the theory of uniformization of Riemann surfaces,we study properties of the Liouville equation and its general solution on a Riemann 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 Riemann surface.
Based on the most important "hard" production mechanism,the production rate of Bc(or Bc) meson being accompanied with one c(or c) and one b(or b) heavy quark jets through Z0 decay is computed in this paper.It is pointed out that at LEP up to next run,quite a lot of events with one Bc or Bc meson may be obtained,so that it becomes accessible to study the properties of Bc and Bc mesons throngh Z0 decay experimentally.
The multiplicity distribution of charged secondary particles and correlation between shower particles and heavy particles of alpha-particle interaction with nuclear emulsion at 12A GeV are discussed.The results indicate the mean multiplicity of heavy particle increase with shower particle numbers.
Based on the Lurie model,a convenient scheme is constructed for calculating the equation of state approximately.The parametric equaion of state is given in the Lurie model.The phase diagram of the model shows the existence of critical point separating first order from second order chiral phase transition.The careful analysis of 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.
The method for constructing the spectrum-dependent solutions to the Yang-Baxter equation,according to Jimbo's theorem,is based on the existence of the representation matrix of e0,corresponding to the lowest negative root,in an irreducible representation of a quantum eveloping algebra.In this paper a conjecture for the existent condition of the representation matrix of e0 is made.As an example,the adjoint representation of Uq C2 is discussed where the representation matrix e0 does not exist because the existent condition is violated.
A model for describing the target fragmentation in high energy hadron-nucleus collisions on the bases of intranuclear cascade is suggested.The analysis of the correlation between grey and black particles shows that the phenomena of saturation about mean number of grey and/or black particles observed in experiments result from the limitation of charge number in the nucleus.
Energy spectra of light charged particles and complex fragments emitted in the interaction of 46.2MeV/u 12C with different target 58Ni,64Ni,12C,197Au and 209Bi have been measured by telescopes,consisting of CsI(Tl) and surface barrier detector stacks.These telescopes for light charged particles and complex fragments have good energy resolution and mass identification.The inclusive data have been analysed within a moving source parametrization.The complex fragment yields from different targets have been compared at several angles.The systematic variation of deduced isotope yields ratios with different reaction systems is used to detemine the N/Z degree of freedom equilibration of the system achieved.
A formula is derived for the density of particle-hole states in the equidistant spacing model.The effect of the Pauli exclusion principle is exactly taken into acount.The pairing effect as well as two energy constraints are involved.The formula is suited for calculating.Comparisons of the results imply that the Pauli effect and the pairing effect play an important role in particle-hole state density.
The mixed symmetry states in nuclei of 150Gd、152Gd and 154Gd are numerically studied with the theory of the neutron-proton interacting boson model.
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