1990 Vol. 14, No. 10
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A simple method is introduced here to correct the bends of the charged tracks,due to the fring effect of the magnet in a forward spectrometer.
Because of the irregular magnetic fields caused by the fringe effect,the track of a charged particle will be twisted when it passes the magnet.By numerical integration,the slope corrections of the track both before and after the momentum analysis magnet have been made.With this method the before and after magnet track matching has been greatly improved and the background,due to the wrong matching,has been reduced.
In this paper the influence of the shape of the exit edge of the single-direction sweeping magnet of its performance is studied.The proper change of the shape of exit edge can improve the sweeping homogeneous degree and decrease unfavourable focusing effect of the magnet.
In this paper we give the helicity formalism of the angular distribution for process e++e－→J/ψ→V+X,V→P1P2 or P1P2P3 and X→pp simultaneously.By using this formalism the moment analysis and some relations have been obtained,which is helpful in determining the spin Jx of the boson resonance X and the helicity amplitude ratios of the process J/ψ→V+X.
In this paper,we calculate anomaly of the left-handed current in the two-dimensional linear σ model by using Bjorken-Johnson-Low limit.We have got the results which are quite consistent with those from non-perturbation functional integration.
The variational cumulant expansion treatment of lattice gauge theory at finite temperature is developed to the lattice SU(2)-Higgs system.The mothod is demonstrated by calculating the expectation value of Polyakov line
The correlated effect arisen from excitations of six-quark clusters in the nucleon-nucleon interaction is studied in the RGM framework and the six-quark configuration effect on the wave function of the relative motion in 1S0 state is analyzed.It is shown that this effect is strong around 1fm and negligible at the distance longer than 2fm.Moreover,this effect pushes the wave function of the relative motion between nucleons outward in some extent in the small RN region and enhances the amplitude of the wave function around 1fm.
Collisions of 1.2A GeV Ar on KC1 in the Bevalac Streamer Chamber are studied using two methods:azimuthal distribution analysis and azimuthal correlation function alalysis.Comparing with the Vlasov-Uehling-Uhlenbeck model predictions for different nuclear equations of state,the stiffness of the high density nuclear matter matter is estimated.The maximum azimuthal anisotropy inferred from the azimuthal distribution method is decreased by about 30% because of dispersion of the azimuthal angle of the reaction plane.This distortion can be eliminated by using the azimuthal correlation function analysis proposed in this paper.
The Linear Momentum Transfer (LMT) in 28Si+238U system with incident energies of 15.0 and 21.7MeV/A have been measured by fission partner fragments.By cutting different regions in LMT distribution,the Sequential Fission (SF) and the incomplete fusion fission events could be separated; as a result,the ratio of SF yield over total fission yield is obtained.Around the reaction plance,the standard deviation of fragment distribution,due to the recoil effect of particle emission on the fragment has been measured and discussed.
The cross sections for 63Cu(n,α)60Co have been measured by using the activation method relative to the cross sections of 27Al(n,α)24Na in the neutron energy range of 13.6—14.8MeV.The values of 58.3±3.1,56.3±2.4,53.4±2.0,50.8±1.9,48.4±1.7,47.4±1.7mb,were obtained at the 13.64,13.79,14.03,14.33,14.60 and 14.80MeV neutron energies,respectively.The results are compared with the published data.The neutron energies were determined by activity ratios of Nb and Zr foils.
The cross sections for 60Ni(n,p)60Co have been measured by using the activation method relative to the cross sections of 27Al(n,α)24Na in the neutron energy range of 13.6—14.8MeV The values of 184.4±12.2,178.8±10.5,171.4±10.3,161.9±9.6,157.0±9.3,147.5±8.9mb were obtained at the 13.64,13.79,14.03,14.33,14.60, and 14.80MeV neutron energies,respectively.The results are compared with the published and to be published data of several authors.The neutron energies were determined by the method of cross section ratios for the reactions 90Zr(n,2n)89m+gZr by 93Nb(n,2n)92mNb.
In heavy ion feaction mechanism experiment,a phoswich array consisting of 20 ΛE-E elements has been used for the measurement of light charged particales emitted at forward angles.The full angular coverage is θL±20°,φL±9°,Different α-particle energies were obtained by degrading the beam with aluminium foils of appropriate thickness for energy calibration.Our experimental data were fitted well by using a fairly simple expression.The obtained α-particle energy spectrum is in good agreement with that,measured by a sillicon by a silicon detector telescope.
The average energies of isovector giant resonances and the widths of isoscalar giant resonances are evaluated with the help of a selfconsistent semiclassical Sum rule approach.The comparison of the present results with experimental ones justifies the self consistent semi classical sum rule approach to the average properties of giant resonances.
The excitation function and isomer ratio of 52Cr(d,2n)52Mng,m reaction have been analyzed by using the Hauser-Feshbach formalism and exciton model considering the conservation of angular momentum and parity.By summing over the calculated contributions of statistical model and deuteron break-up effects with reasonable parameters for optical model,level density and pre-equilibrium model,a good agreement with experimental data not only for the cross section but also for the isomer ratio is obtained.
The micro-correction to the nuclear macroscopic model is studied with a simple liquid drop model by fitting the nuclear masses.It is found that the micro-correction given by Moller and Nix is generally applicable with satisfactory results.Possible regions for improvement are indicated.Sampling calculations indicate that their corrections are also applicable to the continuous medium model proposed by the authors.For nuclear ground state,it is suggested that simplified method of micro-correction calculation may give similar results.
Based on the new form of the distribution density of the reservoir oscillator frequencies,the analytical expression of the density matrix ρ(x,x,t) for a dissipative quantum system has been obtained.The quantum and Non-Markovian effects on the quantum Brownian motion have been studied quantitatively and the Fokker-Planck equation including the quantum effects has been primarily derived under the Markovian approximation.
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