1989 Vol. 13, No. 4
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A brief description of muon identifier for BES was given.The on-line tesing results of a 8-tube muon module with electronics show that both the muon module and the electronic system are stable and satisfy the requirements of muon identifier:good linearity,about 250V plateau,standard deviation of charge division <3cm and padestal walk of electronic system is about ±1 channel.
This paper presents a trigger scheme which has been used in a cosmic ray experiment with a sample-hold readout system.The experiment shows that this trigger scheme can fully collect the whole output signals of the wire chamber for the random cosmic ray events and get rid of the problem of signal loss caused by the delay of sampling gate.Some disscussions about using this scheme for cosmic ray test of BES are also provided.
The focusing properties of a space-charge lens depend on the size,shape and density distribution of its electron cloud.In this paper these parameters are discussed by both numerical and analytical methods.
In this paper,the general transformation of non-abelian gauge field is derived from the in variance reguirement of the effective lagrangian function.It is shown that when the group parameter θ(x) is the product of the anti-commuting ghost field and an infinitesimal number anticommuting ξ which is independent of the component indices space,the B.R.S.transformation is obtained.When θ(x) is equal to the ghost field C(x) times an infinitesimal tensor ξi which is commuting with respect to the upper index b,we get another transformation.Both transformations are proved to be equivalent.
In this paper,the authors find a transformation which connects the covariant formalism with the light-cone formalism in bosonic open string theory,which leads to the connection between covariant statevectors and light-cone statevectors,and yields an orthogonal complete set of states in covariant formalism and a physical projective operator for arbitrary space-time dimension D and intercept of Regge trajectory α(0).The later reduces to the result given by L.Brink and D.Olive in the case of D=26,α(0)=1.Finally,we explicitly show that in covariant formalism,the mass square operator M2≥0 except for the tachyon of ground state.
By combining Monte Carlo method and variational method,we calculate the mass gap of SU(2) lattice gauge theory in 18*18 lattice of 2+1 dimensions by means of the icosaheral subgroup (Y120) using a hamiltonian of which the ground state is exactly known.In the range 0<1/g2,we obtain the results which are in good agreement with analytical calculation of SU(2) group.The scaling behaviour of mass gap am=2.3g2 is confirmed.
This paper shows a new symmetric transformation——C transformation in super principal chiral model and discover an infinite dimensional Lie algebra related to the Virasoro algebra without central extension.By using the Riemann-Hibert transformation.The physical origination of C transformation is discussed.
By incorporating the exact ground state of pure gauge theory and the variational fermion vacuum state,the vacuum structure of 2+1 dimensional SU(2) LGT with fermions is studied.We calculate the fermion condensate <ψψ>,and obtain a good scaling behavior.
The connections between geometric quantization and path integral quantization of bosonic strings are investigated.The Polyakov path integral formulation and its measure are manifestly deduced from the Blattner-Kostant-Sternberg(BKS) kernel of geometric quantization.
The thermodynamical quantities of SU(2) pure lattice gauge field have been simulated first time on the asymmetric lattice (ξ>1).The finite size effect and continuum physics limits have also been studied.The results show that the use of asymmetric lattice is of benefit to calculate the thermodynamical quantities and study the behavior of continuum physics limits.In addition,it is explained that the efficiency of the whole Monte Carlo simulation and the calculation of heat capacity will be improved quite a lot by using bias sampling technique.
A microscopic approach for studying the collective states of odd-mass nuclei is proposed from the viewpoint of interacting boson-fermion model Hamiltonian is derived and used for calculating the spectrum of 157,159Tb and 155,157Gd isotopes.Numerical results are it qualitative agreement with experiment.
The cross section for 107Ag(n,2n)106mAg has been measured by using the activation method relative to the cross section of 27Al(n,α)24Na in the neutron energy range of 13.50—14.73MeV.The values of 469±22,480±22,503±24,538±25,555±25,572±26mb were obtained at the 13.50,13.60,13.90,14.10,14.35,and 14.73MeV neutron energy,respectively.The results are compared with the published data.The neutron energies were determined by activity ratios of Nb and Zr foils.
In this paper a modified surface delta interaction with an angular momentum correction term is proposed.By using this interaction the deformed Hartree-Fock and the approximate angular momentum projection calculations are performed for even-even nuclei in mass region A=56—74.The single particle energy spectra of the ground state configurations obtained are more reasonable than that calculated with KB matrix elements.The agreement of the calculated binding energies and projection energy spectra with experimental ones is fairly good.
The accurate solutions for the low-lying eiginvalues and eigenstates of the single-j CSM hamiltonian have been obtained and are compared with the HFB approximation.There exist a world of difference between the two,especially the behaviour of the yrast and the yrare bands near the bandcrossing and the band interaction strength.The theoretical foundation of the CHFB method for treating the rotating nuclei needs reexamination.
Taking into account the pairing correlation plus the quadrupolequadrupole interaction,the intrinsic properties of the low-lying bands (even parity) and the related E2 transition probabilities in 168Er were calculated in the frame of Bohr-Mottelson-Nilsson model.The agreement between the calculated and the observed results is satisfactory.Some difficulties encountered in the IBM prediction do not appear in the present calculation.
The effective moment of inertia,charge density distributions of the fissioning nucleus 170Yb and 254Fm at saddle point are calculated by using the continuous medium model with variable densities.
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