1988 Vol. 12, No. 2
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By using plastic nuclear track detector CR-39 interleaved with various targets,nucleus-nucleus interaction cross section of high energy Fe nuclei (E≥3.6A GeV) with C,Al,Fe and Cu nuclei at balloon level in Beijing area are measured and the dependence of intaraction cross sections on the atomic weight of targets is obtained.
A high multiplicity cosmic ray event observed in Chinese satellite emulsion is presented.The incident energy and the kind of projectile particle are estimated by using the Castagnoli method and the effective nuclear interaction model.
Beam test results of the 45 degree prototype of the central drift chamber for BES using 0.5 and 1.0GeV/c e+,π+ and p provided by beam K2 at the KEK 12GeV proton synchrotron in Japan are described.The spatial resolution is about 160μm.The integrating nonlinearity of position sensing of charge division is better than 0.5%.The resolution in z direction is 2.3% at the middle of sense wire when the output charge is 1.4±0.2pC.
A composite model with the gauge group SU(3)sc×SU(6) is proposed to explain the family problem.Quarks and leptons are composed of two kinds of massless spin-1/2 preons.Applying Fermi principle and 'tHooft consistency conditions to supercolor-singlet preon composite systems,three generations of quarks and leptons,as required by the experimental observations and the expectation of the Big Bang theory are constructed.Weak bosons are also composed of the same set of preons.This model interprets the low energy weak interaction and does not leads to any difficulty of proton decay.
In the scheme of the improved MK renormalization group transformation,the phase structures for ZN(N=2—6) lattice gauge theories are discussed.Considering the most general plaquette action,the phase diagrams in whole coupling parameter space are obtained,and some results are more elucidating then those obtained by Monte Carlo simulation.The results of this work show that the improved MK transformation is convenient to non-perturbative studies of gauge fields.
By decomposing the distribution function flattice gauge system into the product of single link distribution functions,we obtained a mean field solution to the Fokker-Planck equation in Lattice Gauge Theories.
A paramatrization of KM mixing matrix was proposed by observing the regulari ties of the matrix exposed by experiments.Some physical implications on these new parameters are discussed.The phenomenological constraints on the down-quark mass matrix in the weak interaction base were investigated.A model of the down-quark mass matrix was suggested.in which the KM mixing matrix elements can be estimated in terms of the down-quark masses.The Results obtained in this model agrees with experimental data.
It is suggested that there is internal temperature inside bound nucleons.The relation between this temperature and the bag constant is deduced.It is further assumed that EMC effect could be a result of this temperature,and the values of the internal temperature of nucleons bound in some nuclei are thus obtained.Finally,a value of phase transition temperature is given,and the existence of limiting nucleus is predicted.
We generalize the infinitesimal transformations obtained in the Ernst fields of vacuum previously to the including electromagnetic fields to form a larger infinite symmetric group which is isomorphic to the Virasoro group without a central term.Wherein we find a subgroup,the enlarged Cosgrove group.It is pointed out that new solutions of the electronic fields can be genereated from old ones by means of our new transformations.
Transport theory approach to the parton muliple hard scattering in nucleus and the corresponding Monte Carlo techniques have been developed.The puzzle of Q2 dependence is overcome by bias sampling method.As an example the ratio of π+ production in p (Ep=400GeV)+W reaction to p+p reaction has been calculated.The agreement with data reasonably good.
We have studied the transparency of heavy ion collision at high energy by using Glauber Multiple scattering theory.Good agreement between our calculation results and data available strongly emphasizes the dominance of nucleon-nucleon interaction in nucleus-nucleus collision at high energies.
By using meson cloud bag model we calculate the short range nuclear force in the formulation of the relativistic many body theory.Combination of the contributions from gluon exchange,pion exchange and others,leads to a soft repulsive core of a strength about 250MeV.
The principle for measuring the loss impedance of a storage ring,which is caused by the energy loss of the stored bunched beam in passing through discontinuous parts of the vacuum chamber of the ring,is discussed and the set up to measure the loss impedance of HESYRL storage ring is described.
The measurement results of the energy loss and loss impedance of the dicker vacuum chamber,the septum vacuum chamber and other parts to be installed on the HESYRL storage ring are given.Some of the results are consistent with those measured in DESY.
Yield were determined for 57 fission products from 77gGe to 151Pm in the 14.7MeV neutron-induced of 232Th by γ-ray spectrometry and by chemical separation followed by γ-ray spectromentry.From these data,the total chain vields for 44 mass numbers were obtained.Twelve fission yields are presented for the first time.The yields determined in this work are compared to all known literature values.
γ-γ coincidence and γ-γ angular correlation measurements of 73Br produced in 64Zn(12C,2np) reaction have been performed.The energies and relative intensities of 27 γ-rays are obtained,among them 9 lines and 3 levels have not been reported before.The level scheme of 73Br has been established.The spin of 90.4keV level is inferred to be 3/2－ or (5/2－).
The simulation of quasi-fission reactions induced by 238U was performed by using a simple model,Based on the experimental data,it was proved by such simulation that there is a universal relaxation time in the mass drift mode for 238U induced reaction.The cross sections of the complete fusion reaction and the mass function without the dispersion can be extracted also from the experimental data by such simulation.
An effective and feasible method which is used to measure half-life of short-life nuclei is described.Half-life of the nuclide 26P was measured and its result is 20+35ms. The observed half-life is in good agreement with theoretical calculation.
The nuclear collective motion is described as the variation of the non-hermitian mean field,and the corresponding collective hamiltonian is obtained.
The optical potential and mean free paths of nucleons at finite temperatures in nuclear matter are studied based on the effective Skyrme interaction.The results for nuclear matter are applied within the local density approximation to finite nuclei at various temperatures.The calculation are expected to be limited to nucleon energies between －30MeV below and 60MeV above Fermi energy and to nuclear temperature of less than 8MeV.
In this letter it is shown that even in mπ≠0 case the Goldberger-Treiman relation is still hold in the Skyrme model.The mean square radius of strong interaction of nucleon mπ≠0 is computed in the Skyrme model.
A variational approach is proposed to solve the 5-body Schrodinger equation and an analysis of the ground state wave function is made to extract qualitative features of geometric structure and internal motion of that state.
An alternative way through changing lattice action to calculate glueball masses in SU(2) lattice gauge theory on a 43×8 lattice at β=4.4.The preliminary upper bounds are obtained m(0+)≈(1.38±0.28)GeV,m(2+≤(1.39±0.41)GeV,the ratio m(2+)/m(0+) is near 1.0 or a little small.
Dirac wave functions in six-dimensional Abelian monopole geomentry show a singularity around r=0,in contrast to the five-dimensional theory.Field equations for fermions in soliton background of a six-dimensional pure Kaluza-Klein theory are derived and illustrated by the spherically symmetric soliton case.Neutral fermion equations are decoupled into ordinary differential equations which agree with those obtained by the nulltetrad formalism in the Schwarzschild black-hole case.
We treat baryons as solitons and compute static properties of them in a SU(2)×SU(2) non-linear σ model which contains only a sixth-order term to stabilize solitons.The prediction values in this model are better than that in the Skyrme model,especially the pion decay constant Fπ and the axial coupling constant gA.
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