1990 Vol. 14, No. 7
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The principle and development of the thermionic cathode microwave electron gun used as the injector of a high brightness RF linac are introduced.The numerical computations of the beam current,energy spread and emittance are given.The set-up to test the gun is described and some experimental results are reported.Finally,the article concluded with a discussion of the existing problems and the possible improvements of its performance.
An approximate analytical expression for the radiatively corrected cross section of the resonances in e+e－ collision has been derived with the accuracy to the order of 0.1% for the Z boson as well as the J/ψ and Υ family particles within the experimentally scanned energy range.It is recommended using this analytical expression to treat the resonances which have to be folded with the accelerator beam energy spread in the experimental data analysis.This provides an alternative to the previous method of Jackson and Scharre.It possesses much higher accuracy.
In this paper,the one-gluon exchange interaction between quarks is taken into account in the hamiltonian of the soliton bag model to the zeroth in gs.Can be formed,thus resulting in a soliton bag model with pion cloud.The analytical expressions for the static physical properties of hadrons is derived,and the calculated results agree in the main with the experimental data.
In this paper high-order adiabatic approximate method is proposed to study the evolution of degenerate quantum systums with slowly-changing parameters and varying symmetry.We ont only prove the quantum adiabatic theorem for degenerate cases and discuss the corresponding non-abelian induced gauge structure,but also point out the non-adiabatic corrections resulting from higher-order approximations.With nuclear quadrupole resonance as an explicit example,we use this method to analyse observable effects of non-abelian Berry's phases in adiabatic and non-adiabatic experimental process.
The mixing mechanism of three axial-vector meson f1(1285),f1(1530) and E/f1(1420) is discussed in this paper.The results show that the main component of E/f1(1420) is the glueball.On this basis we calculate the ratio of the helicity amplitudes and expect an experimental test for this result.
The influence of EMC effect on the large-pT direct photon production is discussed.Starting with the statistical model of partons,we make use of the rescaling model to estimate nuclear parameters fitting experimental data of the EMC effect,and calculate the ratio of the cross section for large-pT direct photon production which manifests the EMC effect.It is shown that the EMC effect affects the process slightly,the deviation of the Fe to deterium ratio from 1 is expected to be about 3—－3% in the region of 5≤pT≤10GeV,s=40GeV.
Considering the flavor SU(3) symmetry-breaking in Λ hyperon and using the relativistic two-quark-cluster theory,the ΛN interaction and phase shifts of elastic ΛN scattering have been studied in the quark potential model with the coupling between the quark and mesons (σ+π) taken into account.
The velocities and angular distributions of fission partner emitted from reaction in 28Si+197Au system with energies from 5.5 up to 21.7MeV/A are measured.These results show that when the in cident energies are larger than 10MeV/A,the in complete fusion-fission (ICF) associated with in-complete momentum transfer (LMT) appears.Furthermore,when Ecm>200MeV,as a companion of ICF,the sequential fission (SF) with lower LMT than that of ICF,has apparent yields.By the difference of LMT for ICF and SF over total fission cross-section has been obtained.Meanwhile,the distribution around the reaction plane of one fragment with a standard deviation has been obtained.It seems that there is a simple linear global relationship between the deviation and excitation energy per nucleon in heavier composite systems.
4 symmetric and 6asymmetric BGO Compton shielded HpGe detectors which constitute the Joined In-Beam Gamma Equipment have been completed and measured at the Institute of Atomic Energy (Beijing) and Institute of Modern Physics (Lanzhou) respectively.The first set of experiments has been carried out by using the equipment.This paper describes the experimental set up and the general case of the measurements.A discussion about the Compton suppres sion is given.The observed 25/2+ of the ΔJ=1 band built on the 9/2+ (1g 9/2 proton hole) state of 121Cs is the highest level among the similar bands of other Cs isotopes.
Analytical expressions of some isoscalar factors for U6 SU3,UN (U1)N and SO7 (SU2)3 are derived.
The contribution of the 2H-1P multiple scattering and the TH TDA self-screening to the low energy spectra of 17O and 15O is investigated in various approximations by the method of Green's function and the partial summation of multiple scattering.In our calculation,the nuclear force employed is the Paris potential and the energy dependence on G matrices has been taken into account rigorously.
In this paper,BCS method is applied to reproduce the mass-number dependence on the intrinsic hexadecapole moments (Q40) of deformed even-even nuclei in the rare earth region,and it is shown that the pair correlation is an important factor for explaining such a dependence.The analysis of the intrinsic Copper-pair shows that the nucleon pairs with angular momentum equal to four (G-pairs) make a considerable contribution to the intrinsic hexadecapole moments although the component of such pairs is small.
In this paper a statistical model is successfully used to describe the disassembly of hot nucleus created in intermediate energy heavy ion collisions (15—45MeV/A12C+63Cu).The results of the dependence of mass yield distribution of the fragments on the incident energy are consistent with experimental data quite well.
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