1997 Vol. 21, No. 2
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Using the BES data collected at √S=4.03GeV.the QED processes of e+e－→e+e－,μ+μ－ have been studied. Our measurements agree with the QED prediction,and luminosities obtained from these two final states are compatible at a level of 4%.The total integrated luminosity of 23.1pb－1 was given for all data collected at this energy region from the calculation.
The level schemes of neutron-rich nuclei,141Xe、152Ce、153Nd and 160Sm have been established for the first time through measuring the prompt γ-rays from spontaneous fission of 252Cf.The highest spin state is up to 16+.The collective band structures in these neutron-rich nuclei are discussed.
High spin states of 146Sm have been experimentally studied by using 13C(95MeV) beam bombarding natural Ba target.Seventeen new γ-rays and eleven new levels were found and assigned to the level scheme of 146Sm which extends up to 10.2MeV excitation energy.Level structure still shows the characteristics of particle configurations.No long-lived high spin isomer was found up to such high excitation region.
The events of multicore shower with zenith angle tgθ>4 are found in the emulsion chamber at Mt.Kanbala.Possible mechanisms leading to these,which may predict a new phenomenon in cosmic ray experiments,are discussed.
The coupling problem of the three different intermediate processes J/ψ→ωf2(1270),f2→π+π－ and J/ψ→b1±(1235)π+,b1±→ωπ± included in the hadronic decay process J/ψ→ωπ+π－ is discussed.The consideration of the coupling effect is very important for measuring the parameters of the resonances f2 and b1± and the helicity amplitude ratios of these reactions precisely.
The influence from the transverse momentum conservation of the final particles to the scaling of factorial moments is studied in some detail.The experimental results on the “falling down”of factorial moments in azimuthal angle variable are explained successfully.Two new methods are proposed for calculating the factorial moments in order to eliminate the influence of momentum conservation partly and resume the inherent scaling of the fractal system.
The “Cone algorithm”for the identification of jets is studied in some detail.Two methods are given to identify jets using the momenta of final state particles.Making use of the data sample produced by the LUND-PYTHIA Monte Carlo generator hadron-hadron collision events,the two methods are tested and compared with each other.An effective and pratical method to identify jets is obtained.
In consideration of the lowest order non-perturbative effect due to the quark condensate
The thermalization,expansion and radial flow are discussed in the processes of intermediate energy heavy ion collisions via BUU model.Our results show that at lower energies,the thermalization is reached for the collision system,but at higher energies the global thermalization is violated and only local equilibrium exists.The expansion process in the heavy ion collision at medium energies is also discussed.
Using the two-body correlation dynamics and the time dependent variational principle the equations of nonrelativistic two-body correlation transport theory(TBCTT) for heavy ion collisions are established.This theory is used to discuss Fermionic Molecular Dynamics (FMD) and Antisymmetrized Molecular Dynamics (AMD).The collision effects can naturely appear in the time-evolution equations of its single particle states.
In order to demonstrate the usefulness of Two Body Correlation Transport Theory (TBCTT),by using the Quantum Molecular Dynamics (QMD) without collision term,the numerical study for the semiclassical approximation of TBCTT is carried out.The calculation results show that the TBCTT can well describe the transport and dissipative process in heavy ion collisions.
Based on the non-axial rotor model given by davydov and Filippov,the deformation parameter β and non-axial parameter γ of even-even Er isotopes are determined from the energy of the first 2+ level and the energy ratio of the second 2+ level and the first one.The present work indicates that this model is consistent with the experimental results in the transitional region.It also shows that the non-axial effects on 157Tm nuclide are of importance.
This paper designed a 9—cell RF superconducting accelerating cavity for the TeV electron linear accelerator collider in next century.The ratio,Epk/Eacc,of the maximal surface electric field to the accelerating gradient has been reduced to 2.024 and the cell to cell coupling keeps high to 1.95%.Distribution of the HOM passbands is reasonable.There is no overlap between the bands,therefore no trapped modes.The CSE type structure guarantees the mechanical hardness.According to present state of the art technigue of Niobium surface processing,it is possible to reach 25—30MV/m for the accelerating gradient with beam load.
High spin states in 170Ta have been studied via 159Tb(16O,5nγ)170Ta reaction at 105MeV.Three rotational bands are observed,among which one coupled band and an unfavored ΔI=2 E2 squence are newly found in this owrk.The possible quasiparticle configurations of these bands are discussed.
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