1999 Vol. 23, No. 12
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120Ba was produced by irradiation of 92Mo with 171MeV 32S via fusion-evaporahon reaction channel. The reaction preducts were camed to a low-background region using a He-jet recoil fast tape transport system. Two planar High-Purity Germanitim detectors were put at oppsite sides of the tape so as to make a coincidence measurements. Based on the data analysis, the previously Published γ rays in 120Ba decay were proved and other nineteen y rays with weaker intensity and lowerenergy were also assigned to 120Ba decay. A new decay scheme of 120Ba was proposed.It includes 35 γ rays and 25 energy levels.
The bunching parameters and bunching correlators have been calculated by using the pseudorapidity and azimuthal angle distribuhons of charged prides produced in pp collisions at 400GeV/c. The results show that the values of bunching parameter depend not only on the width of mulhplicity distribuhon. but also on the correlation of particles. The bunching parameters η2 (M) and η3 (M) follow the same power-law behavior in pseudorapidity and azimuthal angle spaces indicating that the multifractal structure in pp collisions at 400GeV/c is observed. The values of the second-order bunching correlators in pseudorapidity space depend on the width of multiplicity distribuhons and decrease with increasing bin-bin disuse D.
This paper, by experiments, describes the properties of lead tungstates (PbWO4 or PWO) which are in different post procession conditions, such as excitation and emission spectra, transmission spectra. fluorescence decay bine, light yield, and irradiation damage. At the same bine the resultS are discussed.
This paper presents a study on radiation damage of lead tungstate crystals (PbWO4),including experimental setup, experimental method and results. Four PbWO4 crystals were irradiated and the light yield of PWO crystal before irradiated and after irradiated were measured. The changes of light yield of PbWO4 with an exponential attenuation was found.
The truncated eigenvalue equation is derived from the improved U(1) lattice gauge field Hamiltonian.The vacuum wave function in 2+1 dimensional U(1) model is computed. The numerical results conform our expectation that the scaling behavior of the vacuum wave function can be greasy improved by improving the lattice Hamiltonian.
We calculate the new contribuhons to the charmless B decay B→Xsη′ via the QCD gluon anomaly and the enhanced b→sg decay due to the charged technipions appeared in Technicolor Model. Widen the considered paraxneter space the new physics contribuhon can result in a large enhancement to the inclusive η′ produchon and in tUrn to account for the CLEO data of Br(B→η′Xs).
By making urs of the diagonal solution of the reflechon equation of the An－1(1) IRF model and the face factorized L operator, we obtain a nondiagonal solution with n+1 pafameters tO the reflechon equahon for the An－1(1) face model.
The method of trUncating eigenvalue equations is used to study glueball mass and glueball wavefunchon. The results of calculahon are (1) the fifth order glueball mass shows no good convergent behavior as μ0 of fifth-order vacuum wavefunction. At region 1/g2>0.8, the glueball mass descends gedully. (2) At region 1/ g2>0.8, the gluball wave funchon μ0F,μ2F become steady, and shows good scaling.
Squeeze-out of nuclear matter in An+ An collisions at 600A MeV are studied. Based on azimuthal distribuhon analysis, a new type of analysis is presented to measured the squeeze-out quantitatively. The influence of dispersion of the azimuthal angle of the estimated reachon plane to the measurement resultS can be removed.
The scaling property of factorial moments in the mulhpanicle final-states of e+e－ collisions is studied in both the laboratory and the thrust-axis coordinate systems by using the Jetset generator. It turns out that in both of the two cases, the 3-dimensional InF2～InM are approximately stndght lines when the phase space are divided isotropically in different direchons, showing that the dynamical fluctuations in the multiparticle final-state of e+e－ collisions are approximately isotropic. In the lab system, the three γ parameters obtained by fitting F2～M of px, py, pz to Ochs formula respechvely are approximately equal. In the thrust system, the three γ values obtained by fitting F2(y)～M,F2(pt)～M and F2(φ)～M are also close to each other provided the starting point in fining F2(φ)～M is chosen appropriately. All of these provide further evidence for the above assertion. Our resultS show that the essential feature, i.e. anisotropy of (approximate) isotropy, of the dynamical fluctuations in soft and hard processes can be revealed by studying the scaling property of factorial moments in the collisions. Therefore, further inveshgation of the scaling properties of factorial moments in various kinds of collision processes is significant for the understanding of the essenhal charetarishcs of collision dynamics.
Within the framework of Hartree-Fock approximation an isospin-dependent nuclear equation of state is obtained by using the extended Skyrme effcehve interachon.The nuclear equation of state is analyzed at different relative neutron excesses. It is found that the binding energy increases with increment of the relative neutron excess,and the nuclear matter critical temperatUre, satUration density and the incompressbility at saturation decrease as a function of the relative neutron excess. It is indicated that the properties at satUration as a function of relative neutron excess sahsfy the parabolic law.
Within the framework of Hartree-Fock theory by using the extended Skyrme effective interaction, the density dependence of symmetry energy is derived analytically with parabolic approximation at zero-crmperature. It is shown that the parabolic approximahon is applicable within a rather large density region and almost for all relative neutron excess. The symmetry energy depends on density terms of ρ2/3,ρ, ργ+1, ρ5/3 and ργ5/3. At finite temperatures, the Parabolic approximahon between symmetry energy and relative neutron excess is still appropriate. In addition, the temperature dependence of symmeny energy is predicted. It is found that the symmetry energy decrease with increment of tempendre and the Parabolic law between symmetry energy and temperatUre is satisfied at lower temperatures.
The effect of in-meditim isobar in strange hadronic mattert(SHM)is studied wilson the framework of the relativishc mean field(RMF). As far as the effect of the in-medium isobar is concerned, we find a second stable state comes intO being in the higher density scope in SHM and thes effect promotes the producing of Ξ hyperons through the reachon AA-ΞN This effect is consistent with the conclusion that Ξ hyperons are conshtuents of SHM.
The influence of the fluctuation in γ-transition energies and the I=1 staggering on the spin assignment of superdeformed band is inveshgated for the doubly odd nuclei in mass A≈190 region. The extracted fluctuations in γ-transition energies are not too large, implying a weak innuence on their spin assignments except for the fitting parameters and precisions. In addition, the I= staggering in superdeformed signature partner pairs of doubly odd nuclei behaves differently from that in odd-A nuclei and can be understood in the framework of the collechve model.The existence of I=1 staggering also exefts no influence on the spin assignment except for a renormalizahon of fithng parameters. A modified ab-expresion valid in doubly odd nuclei is proPOsed. The smoothed ti'ansihon energies are employed to assign the spins of these superdeformed bands by the ab-fitting and itS modification.
The Vlasov equahon is solved by expansion in terms of generalized Laguerre polynomials. Some stUdies on microwave instability are done based on the code and some resultS are obtained.
If the identical cavity tanks are applied to coupled-cavity drift tube linac (CCDTL) structure in a proton linac, the fabrication and tuning procedures of the CCDTL will be simplified, and the cost of the linac construction can be reduced. In this paper new definition of particle dynamics coefficients is introduced, a design method of identical cavity CCDTL tanks is discussed, some calculation results are presented.
The nonlinear space charge effect of bunched beam in linac is one of the important reasons that induce the emittance growth. The general formulas for calculating the potential of space charge with nonuniform distribuhon in surrounding structure are presented. For a bunched beam with different distribuhon in waveguide of linac, the expresses of the nonlinear field energy of a cylinder model of space charge are derived, and the numerical results of the nonlinear field energy for different density distributions are given. The emittance growthes caused by these nonuniformities are discussed.
The technique of the geometric design and graphic displaying of GEANT3 is adopted in the SHIELD code. Some examples of complicated spallation targetS are designed and discussed. With the proton beam energy of 150MeV, our results show that the best thickness of W spallation target is scm, 5.0-5.8 neutrons can be produced per GeV of beam energy for properly designed W target the material damage and the radiation deposits are concentrated in the beam axes of about 2cm long, scattered proton beam may alleviate the concentration, but may also lower the neutron production.
Single crystalline silicon specimens are irradiated at room temperatUre with 750MeV argon ions. Positron lifetime, electron paramagnetic resonance as well as infrared optical absorphon measurementS are conducted tO study the radiahon induced defects in the specimens. It is found that neutral divacancies are the main vacancy clusters induced by the irradiations. UP to 4.3×1014ions/cm2 no amorphous phase is detected. At the end of the range the divacancy concentrahon increases dramahcally with increasing dose whereas in the electronic processes dominating area the concentration of divacancy saturates. It is therefore proposed that the radiahon induced defects can be annealed by the energy deposihon through electronic processes.
It is shown that the Pomeron could be regarded as a Reggeized Tensor Glueball with a trajectory of ap(t)=1.08+0.2GeV-2t. Under mis theory, the total cross section measured for pp elastic scattering at high energies is reproduced successfully. The best fits to experimental data lead to a Γξ→pp=9±3MeV and Γξ>50MeV J=4 for spin of the tensor glueball mξ(2230) is precluded.
A new relativistic and singularity free form factor for baryon vertex is suggested.The form factor sahsfies the crossing symmetry of scattering axnplitude transfered from t-channel to s-channel for strong interaction Processes.
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