2002 Vol. 26, No. 4
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The newly developed single trajectory quadrature method is applied to solve the ground state quantum wave function for Coulomb plus linear potential. The general analytic expressions of the energy and wave function for the ground state are given. The convergence of the solution is also discussed. The method is applied to the ground state of the heavy quarkonium system.
Using the dynamical transport approach RQMD, the radial collective expansion in relativistic heavy-ion collisions is studied at RHIC energy. The prediction of the radial flow is presented by analyzing the transverse mass spectra for Au+Au central collisions at the center of mass energy s=200AGeV. We conclude that the average radial flow velocity is 0.6c and the freeze-out temperature is 160MeV in Au+Au reactions.
We show that the ξ(2230) must have a width much broader than the reported 20MeV. A broader width does not necessarily rule out the ξ(2230) as a glueball, but it does explain why the meson cannot be seen in p p experiments. Therefore, the controversy between different experimental results does not rule out the existence of the tensor glueball ξ(2230).
In virtue of the simple physical picture of quark combination model and the probability for the production of a qfqf of a flavor f which is given by treating the pair creation of the qq as a quantum mechanical tunneling effect, an universal mass relation for direct hadron production rates,
A supersymmetric vector-like standard model without leptons is suggested to investigate the unification between gauge interactions and gravity under two loop approximation for gauge interactions and one loop string correction for gravitation. It is found that two intermediate mass scales are needed where the lower mass scale may be accessible in laboratory in future and the higher mass scale is of the order of 1016GeV.
The generator of gauge transformation for spinor QED with Chern-Simons (CS) term has been constructed. According to the rule of path integral quantization for constrained system in Faddeev-Senjanovic scheme, the phase-space generating of Green function is obtained, and canonical Ward identities for such a system is also derived. The quantal conserved angular momentum for spinor QED with CS term is studied. The property of fractional spin of the system is pointed out.
In this paper, the excited odd q-coherent state a+m qα> oq and excited even q-coherent state a+m qα> eq are constructed. The q and m dependences of mean photon number and sub-Poissonian character and antibunching effect are numerically studied. It is shown that when the q is far from 1, the second-order q-correlation function exhibits oscillating phenomenon, whose amplitude and period are independent of m; but the mean photon number and the Mandel Q q parameter increase greatly as m increases; and the sub-Poissonian character is not equivalent to the antibunching effect unless q→1.
The new supercharges are constructed and the weight function is defined to study the N=2 one-dimensional supersymmetric quantum mechanics. Several examples are discussed in the new realization.
We discuss about the nature of f0(400-1200) which we decompose into three parts, i.e., t-channel ρ meson and f2(1270) meson exchange plus an additional s-channel resonance f0(X). Below 1.2GeV of ππ invariant mass, t-channel ρ meson exchange can explain the I=2 ππ S-wave scattering very well. However, the f2(1270) meson exchange must be considered for the ππ invariant mass above 1.2GeV. With the t-channel ρ meson and f2(1270) meson exchange fixed by the isotensor ππ→ππ S-wave scattering, we re-fit the CERN-Mülich(CM) data on ππ scattering to get parameters for the f0(X). We find that it is necessary to introduce a broad 0++ resonance with a pole about 1.6-1.7GeV.
The level structure of doubly odd nucleus 142Pm has been studied via the 128Te(19F,5nγ)142Pm reaction in the energy region from 75 to 95MeV. In-beam γ rays were measureed including the excited function, γ-ray singles and γ-γ coincidences in experiment. The level scheme of 142Pm has been extended up to excitation energy of 7030.0keV including 25 new γ rays and 13 new levels. Based on the measured γ-ray anisotropies, the level spins in 142Pm have been suggested.
High-spin states of 143Tb have been studied via the 118Sn(32S,1p4n)145Tb reaction by means of in-beam γ-ray spectroscopy. Measurements of γ-ray excitation functions and γ-γ-t coincidences were performed with 12 BGO(AC)HPGe detectors. A level scheme for 145Tb including 41 γ-rays which come from the deexcitations of the 24 levels, has been established for the first time based on an analysis of the γ-ray excitation functions, γ-γ coincidence relationships, intensity balances and cross-over transitions. The spins for most of the levels in the scheme are assigned according to the results of the measured γ-ray anisotropies. Considering the structure similarity between 143Eu and 145Tb, the low-lying levels in 145Tb are interpreted by coupling a h9/2 proton to the excited states in 144Gd core.
The double Q2-rescaling model is used to calculate the variation of K-factor with x2 when the nucleus A-nucleus A collision (for example, C, Ca, Fe, Sn) occurs at different values of x1, where x1 and x2 are momentum fraction variables. In this calculation, the contributions of annihilations and Compton scattering have been taken into account in the Drell-Yan process. The numerical results show that the plots of K-factor versus x2 are somewhat dependent on the values of x1 and that K-factor could not be regarded as a constant because it changes with A-nucleus to some extent. These results can be used to test the validity of the nucleus model and the adaptability of QCD theory.
Using the Particle-number Conserving (PNC) method for treating the cranked shell model, the high K multi-quasiparticle bands in odd-A deformed nuclei 173,175Hf are analyzed, including the variation with rotational frequency of the moment of inertia, angular momentum alignment and occupation probability of each cranked Nilsson orbital. No free parameters are involved in the PNC calculation and the experimental results are reproduced well. The microscopic mechanism of the difference between the multi-quasiparticle high K bands and the yrast bands in neighboring even-even nuclei is investigated, where the blocking effects of high j intruder orbitals near the Fermi surface play a crucial role.
The role of momentum dependence equation of state on the nuclear stopping for the isospin dependence and the isospin independence of in-medium nucleon-nucleon cross section is studied by using the isospin dependence quantum molecular dynamics. The nuclear stopping depends strongly on the isospin dependence of in-medium nucleon-nucleon cross section and weakly on the isospin dependence of the mean field-symmetry potential from above the Fermi energy to about 150MeV/u for the small impact parameters. A detail study indicates that the difference between the nuclear stopping for the isospin dependence and the isospin independence of in-medium nucleon-nucleon cross section depends sensitively on the momentum dependence interaction, namely, the difference between the nuclear stopping for the isospin dependence and the isospin independence of inmedium nucleon-nucleon cross section in the present of momentum dependence interaction is larger than that without the momentum dependence interaction (MDI) for the mass symmetry and mass asymmetry reaction systems, neutron-rich and neutron-poor reaction systems. Namely, MDI increases the sensitivity of the nuclear stopping on the isospin dependence nucleon-nucleon cross section. Therefore, the knowledge on the isospin dependence of in-medium mucleon-nucleon cross section can be extracted more accurately from nucleon stopping as a probe if the momentum dependence interaction is taken into account.
The effect of collective flow on two pion interferometry is studied using two pion interferometry at small relative momentum. The analytical relation between the apparent radius and real radius of the pion source is given.
The φ meson production in relativistic nucleus-nucleus collisions is investigated systematically using a hadron-string cascade model LUCIAE. Within the framework of the model and relying on the collective effects in the gluon emission of string and the reduction of the s-quark suppression, the NA49 data of φ meson enhancement in the 158 A GeV/c Pb+Pb collision relative to that in p+p collision at the same energy is reproduced in certain extent.
TEXONO collaboration adopts CsI(T1) crystal to measure the energy spectrum and abnormal magnetic moment of reactor neutrino. The paper describeds the principle of measurement, the structure of detector and its electronics, and the performance. Because of good position and energy resolution the detector can be used to measure both energy spectrum and neutrino hit distribution. The good PSD of detector provides strong ability to identify the neutrino events from backgrounds.
Lie algebraic method is used in the analysis of nonlinear transport for the relativistic charged particles in cylindrical symmetrical electrostatic fields, and particle orbits of third order approximation in the six dimensional phase space (x, x′, y, y′, τ, p-τ) are obtained. In the analysis, we take the electrostatic accelerating tube as an example, and divide the electrostatic accelerating tube into three elements: entrance thin lens, uniform accelerating field and exit thin lens, on which Lie map is applied, and the solutions through third order of particle orbits are obtained finally. This method can also be used for the electrostatic lenses.
The dependence of the performance of the rotating coil magnetometer on its parameter and fabrication error is studied. The expressions of the measurement error due to the fabrication error are given. The results show that, the rotating coil magnetometer is an effective instrument to measure the field distribution of the multipole magnets, by measuring the dipole field the position ot the magnetic center of the magnet relative to the rotating center of the magnetometer can be determined, and the magnetization curve of the magnets can be measared by it also but the measurement accuracy is limited by its fabrication error.
The theoretical analysis of the DC K-modulation of quadrupole for the beam-based alignment method is presented. It is shown that the shift of the orbit,when the focussing strength of one quadrupole magnet is changed,can be described by the perturbed or unperturbed linear lattice parameters. The beam-based alignment system is constructed using DC K-modulation of quadrupole. In order to use the beam-based alignment method one must be able to individually adjust the strength of the quadrupole magnet. So,a switchable shunt resistor is installed on quadrupole to bypass 1%-2.5% magnet current and some solid-state relays are used to switch the shunt resistor in this beam-based alignment system. To improve the measurement accuracy,two methods are used. First method is that beam positions in measured quadrupole magnet are moved by local bump of beam closed orbit using the corrector magnets. Second method is that the root-mean-square of difference in closed orbit is fitted by a parabola function. The system can be not only used to position the beam in the magnetic center of quadrupoles,but also to measure the β function in quadrupole magnets. Some preliminary measurement results are given for Hefei 800MeV electron storage ring. These experimental results show that this system is valid to position the beam to the center of the quadrupole magnets and measure the β function at Hefei Light Source.
According to the storage ring injection requirements of Shanghai Synchrotron Radiation Facility (SSRF),an eddy current septum magnet prototype has been firstly constructed in China. All measured specifications of the magnet are very well satisfied with the requirements of the storage ring injection. In this article,some key issues of the design and construction of the septum magnet are discussed,the measured performances of the septum magnet are given and some constructive suggestions to improve the performance of the septum are proposed.
Tumor treatment with heavy ion is characterized by the depth-dose curve of heavy ions. So,it is a key to develop physics model for calculating dose. In this paper, the media for calculation have been selected from the chemical component of biological cells,characters of radiobiology and demand of physical dose calculation. A method to calculate does-depth distribution has been developed by using the semi-empirical functions of nuclear fragmentation reaction cross section and total nuclear reaction cross section,and also considering other factors which affect the results of calculation. The results of calculation tally with experimental data and show that the theoretic calculation can be used in the tumor treatment and radiobiology effect research.
Polycarbonate films were irradiated with 2.1GeV Kr ions at room temperature in vacuum and in atmosphere,respectively. The ion beam induced effects were studied by means of Fourier transform infrared (FTIR) and ultraviolet visible (UV/VIS) spectroscopies in reflective mode. FTIR measurements indicate that the main effects are bond breaking,chain scissions and bond rearrangement. The creation of alkyne is the result of bond breaking and bond rearrangement. UV/VIS measurements indicate that at wavelengths of 380,450 and 500nm,the normalized absorbances follow approximately a linear relationship with the energy deposited density.
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