1998 Vol. 22, No. 10
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The radiation damage of CsI(TI) crystals after irradiation in radiation fields formed by 1.3 GeV electron beams and Cobalt-60 radiative source are investigated. The variations of the light yield and the transmittance, the natural recovery and the heat annealling recovery of the radiation damage are measured.
The entropy indices of QCD branching process are calculated from the data of 400GeV/c pp collisions. The nonzero values of entropy indices are obtained. The entropy indices are increased with decreasing average multiplicity's of the final states. It means that the is a chaotic sign in pp collisions at 400GeV/c.
The event generator LUCIAE has been used to simulate relativistic nucleus-nucleus collisions. The strange meson K0s and strange baryons A and A production in S+W central collisions at 200A GeV has been analyzed. The transverse mass spectrum for them and relative production rates of strange meson to strangebaryon are obtained and compared to the data of experiments.
The high spin states and octupole deformation collective bands of neutron-rich nuclei 144,146Ce have been established through measuring the prompt γ-rays from spontaneous fission of <252/sup>Cf. The highest spin state is up to 15－. The characteristics of octupole deformation for the two nuclei are discussed.
The Wilson fermion condensates in the lattice Schwinger model is calculated by using improved Hamiltonian and variational method. The calculated result depends on the Wilson parameter much weaker than before.
Within the framework of linear response theory, we use the effective propagator including the internal line particle's finite width to study the energy loss rate of a fast moving parton's caused by the inducive field when it penetrates throught QGP, A reasonable interpretation to the numerical result is provided.
With the power series expansion of the three-pion correlation function at small relative momentum, the relation between the three-pion correlation and root-mean-square radius of pion source is Obtained analytically. The relations between the space parameters of the pion source from 3π interferometry and 2π interferometry are also obtained when multi-pion correlation in three-pion events is or is not considered,The distortion of the two-pion coherence factor caused by the multi-pion correlation in three-pion events is calculated. And comparison is made between the results of 2π interferometry analyses at small relative momentum and the experimental measurements of the central relativistic heavy-ion collision 1.8A GeV Ar+Pb.
The quantum statistical effect for K and π production in 200A GeV S+S and S+Ag collisions is studied. The calculated results reproduce the experimental data well. The extracted freeze-out temperature is ～110MeV and the baryon density is ～0.05ρ0.
The descriptions for nuclear shapes in a general case are discussed, and the symmetry properties for nuclear systems of different shapes are presented. The corresponding numerical algorithms are constructed.
The relativistic microscopic optical potential,the Schrodinger equivalent potenlial and mean free paths of a nucleon at finite temperature in nuclear matter with different nuclear density are initially studied on the basis of Walecka' s model, the thermo-fielddynamics and the relativitic Dirac-Brueckner-Hartree-Fock approach. The calculatted results show that the dependences of the Schrodinger equivalent potential and mean free path of a nucleon on nuclear density are fairly sensitive and the dependences on nuclear temperature become more sensitive when nuclear density is larger.
The reduced widths of the momentum distribution of the projectile-like-fragments from the fragmentation process are calculated for fitting the experimental data in a wide energy domain based on a quantum statistic physics model. The systematic evolution of the fragmentation process with incident energies is discussed.
This control system is used to flatten the flat-top of the amplitude and phase macro-pulses of the high power klystron output.This is of critical importance in improving the electron beam quality for FEL and other applications. The self-adaptive feed-forward control system is adopted to stabilize the RF power supply for the LINAC, which utilizes linearization and matrix algebra to simplify the computation. The system is operational and some experimental results have been obtained, which demonstrate that the system is effective to improve the beam quality.
The character of the newly developed RFD structure is studied by means of lens approximation. The equations of particle motion functions, transfer matrices of RF lens and stability conditions of particle acceleration are presented.
It is shown that beam self-field effects induce nonlinear resonances and chaotic behavior in uniform or periodic focusing channel by means of particle-core model and Poincare mapping technique. In order to explore self-consistently the fundamental properties of breathing round beams propagating in a uniform channel, the initial phase-space distribution of a beam injected into a linac is adopted to be a sufficiently realistic distribution such as Gaussian, waterbag and parabolic distribution Multiparticle simulations are performed and a series of results such as halo intensity and emittance growth are obtained.
The beam intensity and its distribution from the new installed 3W1 Wiggler at Beijing Synchrotron Radiation Facility of BEPC were measured. The experimental results quite consist with the theoretical calculation.
The dibaryon mechanism is suggested for Pion-Nucleus double charge exchange reaction. The calculations within this mechanism are performed for 18O(π+,π－) 18Negs reaction at the energy of 164MeV.The principal finding from this study is that the dibaryon mechanism may exclusively be responsible for solving many long-standing puzzles of 164MeV double charge exchange reaction on the target 18O.
The new neutron-rich nuclide 209Hg has been identified for the first time. An on-line, gas-thermochromatographic technique was developed for rapidly separating mercury isotopes produced by 600MeV 18O+(thick target) reaction. A special detection method was used to detect the - delayed rays from neutron-rich mercury isotopes. The half-life of 209Hg was determined to be 35+9－6s.
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