1991 Vol. 15, No. 4
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The structure of an 1GeV/c wide-range magnetic spectrometer is briefly described.The spectrometer includes the magnet system and the detector & data acquisition system.The momentum formula at extended edge field case for non-focusing magnetic spectrometer has been derived.The momentum resolution,solid angle,momentum acceptance and other parameters for this spectrometer are calculated by Monte Carlo simulation.The effects of the multiple scattering and position resolution of the detectors to momentum resolution of this spectrometer are discussed.
The electron clouds in high vacuum which are confined by electromagnetic fields and sustained by thermionic emission are studied.The distributions of the electron density,the electron temperature,the drift angular velocity of electrons,the diffusion flow density of electrons and the electric potential in the electron cloud are discussed.
In this paper,the quantum cosmology of Einstein-Yang-Mills has been studied.The Hartle-Hawking proposal for the boundary conditions of the Universe is extended to Eight-dimensional Einstein-Yang-Mills theory.A minisuperspace wave function is calculated in the classical limit corresponding to a superposition of classical solutions in which four of the dimensions remain small while the other four behave like an inflationary Universe.
The effect of the evolution of partons in nuclear environment to the structure function of nucleons bound in a nucleus is investigated.Together with the nuclear shadowing effect caused by the spatial overlap of partons from neighboring nucleons in the nucleus in the small x region,the ratio of the average nuclear structure function of nucleus 56Fe to the deuteron structure function is calculated and a good agreement between the calculated results and the experimental data is obtained.
We have calculated the energy spectra of the hypernucleus 9Be up to about 15MeV excitation energy by using an α+α+Λ three-cluster model and using the hamonicoscillator product states as basis function.By analyzing the shape densities in detail,we have determined the most probable shapes in three low-lying ststes of Lπ=0+,2+ and 1－
The relation of isotopic distribution of the heavy ion peripheral reaction products in intermediate energy range to neutron-skin and excitation energy has been studied.The thickness of neutron-skin predicated by the droplet model and emperical one-body disspation in the intermediate energy range has been considered.The experimental isotopic distribution produced by 40Ar and 86Kr as projectiles in the intermediate energy can be reproduced by calculation.
The excitation functions,angular distributions and differential range distributions have been measured for target residues from the reaction of 65Cu induced by 45—96MeV 16O ions with radiochemical techniques.A comparison of the experimental data with Monte-Carlo simulations based on the statistcal model of compound nucleus that the heavy residues are produced by the decay of a compound nucleus formed by complete fusion.Incomplete fusion or massive transfer are the main reaction mechnisms leading to production of the residues with mass number close to that of the target.
Some parameters and the β equation of Johansson mass formula were modified.In the fit to the experimental masses and two-neutron separation energies (S2n) of 640 nuclides in the region of 50≤Z≤71,four free parameters are presented.The root-mean-square deviation of the mass values and S2n are 0.827MeV and 0.406MeV respectively.The characters of transition from spherical to deformed shapes (N>90) are also reproduced by the curves of S2n.
The design of a ECR ion source in a working mode with a ωecr resonance surfaces and a 2ωrf enclosed surface is presented.The 0.8T axial mirror field and 0.8T radial hexapole field are introduced with detailed discussions.The computational results show that the axial length of the ωecr resonance surface in the improved ECR ion source is extended significantly compared with the original CAPRICE one and a closed 2ωrf equigauss surface is also formed.The new topology of the magnetic field in the improved ECR ion source will largely raise the intensity of high charged ion on the basis of the analysis of ionization mechanism.
This paper investigates the mass,shell and even-odd effects of the nonstatistical and statistical processes in the radiative nucleon capture reactions.The (n,γ) cross sections for 33 even-neutron target nuclides were studied at En of 0.1 to 3MeV.The results indicate that the nonstatistical capture cross sections do not present any systematically varying pattern with mass number,except for a weak shell effect.The statistical capture cross sections,which depend strongly on the level density,display obvious mass,shell and even-odd effects.The nonstatistical fractions show prominent downward tendency with mass number,as well as the shell effect.
The current situation on the glueball research is reviewed in this paper.The emphases are some qualitative guidances to identify the glueball and several possible candidate states for the glueball which have been discovered in the experiments.
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