1989 Vol. 13, No. 10
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Multiplicity distributions and pseudo-rapidity distributions of charged particles from oxygen-induced nuclear reactions at 14.6 and 60MeV/nucleon are presented.The data were taken from the EMU-01 emulsion stacks and compared to simulations from the Lund Monte Carlo Model (FRITIOF).
The test and calibration of the detectors of the BES luminosity monitor were performed at KEK Japan.In the momentum region from 0.25GeV/c to 4.0GeV/c,the properties of the shower counter,such as energy resolution,energy linearity,homogeneity and time resolution were measured.The energy resolution of the shower counter σE is approximately 13% at 1.5GeV/c.The time resolution is 660ps.The performance of the defining counter and the complementary counter was also measured,and the energy resolution was 30—40%,the time resolution was about 300ps.The experimental results show that the properties of all these detectors are satisfactory for the BES luminosity monitor.
On the basis of one simple grain boundary model,the trapped states of positrons at grain beunaries in pure Aluminium are solved and the corresponding positron annihilation lifetime spectra are calculated.The correlations between the atomic density distributions of grain boundaries and the lifetime spectra are discussedand the existing experimental results are explained theoretically.
We analyse in detail the advantage and disadvantage of the Quark Combination Rule in the explanation of BB correlations.Under the assumption that quarks and antiquarks in one jet must be in pairs.the BB correlations calculated are consistent with the experiment on the whole.
By joint possessing quarks model,we studied the effect of quarks in nuclear weak interactions,calculated the width of Λ non-mesonic decay in different hypernuclei,and compared the results with the measurements and other existing calculations.
Higher moments of the multiplicity distributions in high energy hadron-nucleus collisions are calculated in the framework of the Multisource Model.The results are in agreement with the data presented by N.N.Biswas et al.It naturally explains the break down of the universality of KNO scaling in high energy hadron-nucleus collisions.
The cumulant expansion is used to calculate the mean-plaquette internal energy for d-dimensional SU(3) gauge theory.We use the methods of series expansion and steepest descent to calculate SU(3) one-link invariant group integral.These two methods agree accurately with each other.The results show that the cumulant expansion is effective for 3-dimensional lattice gauge theory.
Based on the α-cluster models,variational calculations for 9Be,6Be AND 10Be have been completed with the aid of the harmonic oscillator expansions and the generalized Talmi-Moshinsky transformations.Under uniform α-α and Λ-Λ potentials,the unified descriptions for 9Be,6Be AND 10Be are achieved by introducing a modified Λ-α potential.We have also studied the structures and correlations between particles in the calculated states of these hypernuclei and obtained some interesting results.
A quark model calculation for the short-range contribution in the pion double charge exchange (DCX) reaction is presented.In the framework of this new model the angular distributions of 18O(π+,π－)18Ne(g.s.) at low energies are calculated and compared with the experimental data.It is found that this model can explain the "anomalous" increasing behavior for the DCX reaction around 50MeV quite well.
By using the Jastrow correlation wave function,the role of nucleon-nucleon short-ranage correlations in the nuclear structure function is reanalzed.The result shows that,with the correct single-particle energies and the proper momentum density distribution of nucleons in the nucleus including the effect of nucleon-nucleon short-range correlations,the experimental data of the nuclear structure function in the x>1 region could not be well explained.
The main formulae of finite temperature semiclassical method are presented for a local potential.The properties of hot nuclei,especially the heat capacity and incompressibility,are calculated and discussed.Some results are compared with finite temperature HF ones.
The measurements of fast neuton capture cross sections of Eu relative to Au at six neutron energies were carried out by using a large liquid scintillator detector.The neutron capture cross sections of 151Eu and 153Eu were calculated in the range of 0.1 to 2.0MeV using the optical model and statistical theory.Present results are compared with other experiment and discussed.
Exciton of a composite system at high energy is divided into two subsystems which consist of memory particle m and non-memory particle r.After introducing an the collision factor of m-particle in state n,the coupled master equitions of the occupation probability of stateangle of m-particle and r-particle are established.The expression of state density,taking into account the distinquishability between m-particle and r-particle,and the formulas of the rate of β-particle emission of m-system and r-system in state n are also given.The calculation results show that the fit with experimental data is improved conspicuously and is much better than that obtained from the generalized exciton mdel.
In this paper a new form of the Hamiltonian of the massive lattice Schwinger model is proposed and its exact ground state is found.The string tension is calculated exactly and the result is 1/2e2 for both Naive and Susskind fermions.
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