1990 Vol. 14, No. 8
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A simulation method for trajectories of charged particles in the real magnetic fields is introduced for the forward spectrometer in experiments of high energy physics.By using the numerical integrations to the Lorentz equation,simulation tracks with good accuracy have been obtained.
By using BWS-5k II streak camera made in China,we have measured the time structure of Synchrotron Radiation (SR) from the relatrivistic electron and positron beam bunches of Beijing Electron Positron Collider (BEPC).The dependence of SR width to the intensity of beam current and the voltage of RF source was also measured.The main data taken with 30ps time resolution in the experiment are as follows: The length of VR at Ee=1.549GeV is changed from 220ps to 670ps when the average beam current from 2mA to 30mA,the variation range of CR length at 20mA beam current is 500—700ps with RF source voltage varying between 250kV and 500kV.The time calibration uncertainty of the experiment is ±15%.The trigger jitter is less than ±200ps.
We indicate that final state interactions can be neglected if one calculate deep inelastic lepton nucleus scattering in the time-ordered perturbation theory in the infinite momentum frame,or its equivalent,the light-cone perturbation theory in an ordinary frame.We thus extend the light-cone quantum field theory to baryon-meson field to establish a relativistic composite model of nuclei,and then apply the impulse approximation to deep inelastic lepton nucleus scattering in this model.
In non-adiabatic cases the topological action assocaiated with Berry's phase and the corresp onding effective Hamiltonian are obtained by path-integral method.We also give the non-adiabatic transition probability amplitude in the first-order approximation.It is thereby shown that the Berry's phase and the induced gauge structure have universality of existence.As an example,dynamics of induced monople relating to the Bitter-Dubber's experiment is analysed in terms of induced gauge field.
The β function behavior for SU(3)×SU(3) chiral model on 2-demensional random triangle lattice has been studied with Monte Carlo renormalization group method.The behavior is similar to that of the 4-dimensional SU(3) gauge theory,but it has a smoother transition from weak to strong coupling regions.There is no nonperturbative peak structure.The asymptotic scaling starts beyond β=5.8.
Recently,a new effect,which nay be called the mechanical Aharonov-Bohm effect,was suggested and verified experimentally.In this paper,we proceed to study and calculate the mechanical Berry's phase and corresponding topological phase angle.
In this paper,we give a solution to fundamental problems of Wess-Zumino-Witten model for the case j3=1 and the method of solving the fundamental problems for the general case.We find also the explicit connection between the crossing matrix of SU(2)t WZW model and the braid matrix of SL(2,q) quantum group,the latter is just the quantum Racah coefficent.
The effect of multi-pion correlations on two-pion interferomentry in a multi-pion event is studied.A new general two-pion interferometry method is developed,by taking into consideration of the effect of multi-pion correlations.Data for 1.8A GeV Ar+Pb central collisions at the Bevalac streamer chamber are analysed by using this new method.
The saturating chiral breaking field theory are used to study thermostatic properties of nuclear matter for different regions of temperature in the framework of mean-field theory.The results given by Chowdhury et al.are improved and developed.By using the numerical integration for the Fermi integral,we find the low temperature approximation taken by Chowdhury et al.to be valid only when βμeff>2.4.The critical temperature Tc for the liquid-gas phase transition is obtained to be about 23MeV and the phase transition of the nucleon-antinucleon plasma is found in the range from T=150MeV to T=200MeV.
According to the distribution of linear momentum transfer (lmt) obtained from the correlation measurement of fission partner,the events of Incomplete Fusion Fission (ICF) and Sequential Fission (SF) were distinguished.The fission angular distributions of both ICF and SF were obtained,respectively.
With calculating the moment of inertia by Cassinian Ovaloid as the fission shape, the angular distributions were fitted by current procedure.The spins of fission nuclei corresponding to ICF and SF are extracted.The relation between spins and bombarding energy is discussed.Besides,the angular distribution in coincidence with complex particles is discussed.
Cross sections and average forward ranges were determined for 35 target residues from the interaction of copper with 44MeV/A12C ions with nuclear chemistry techniques.From these data the isobaric yield distribution,the mass yield distribution and the longitudinal momentum transfer were obtained.The mass yield distribution and the isobaric yield distribution are in good agreement with those calculated from a modified statistical model and corresponding Monte Carlo technique.
A simple calculation method for charge for charge density distributions of deformed nuclei by using macroscopic model has been proposed.The calculations of charge density distributions for 192Os,154Gd,152Sm,174Yb, and 144,148,150,152Sm nuclei have been performed.The results show that the calculated charge densities are in good agreement with experiments.Consequently,on the base of experimental data of the transition probabilities for ground state to 2+,4+,6+ rotational states or its electric multipole moments,The charge density distributions of deformed nuclei can be predicted theoretically by this method.
The effect of nuclear rotation to the EMC effect is discussed and a method for measuring nuclear collective rotational current suggested.
The S wave phase shifts of N-N scattering are calculated by using the equivalent one meson exchange potential (EOMEP) and equivalent 2π exchange potential (ETPEP) from the quark-antiquark pair creation model.The result shows that EOMEP and ETPEP can provide a part of medium attractive nature of the nuclear force.
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