1995 Vol. 19, No. 9
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650 thousands of EAS events recorded by Huairou EAS Array have been analysed carefully. The Size spectrum and primary energy spectrum in the region from 1015 to 1016eV are obtained. The energy spectrum shows a clear and smooth "Knee" structure around 3×1015eV. Except the smooth steep feature of "Knee", it is consistent very well with Akeno spectrum. Under the assumption of so-called rigidity dependent cut model, by adjusting the breaking energy Ec of primary proton spectrum in the Monte Carlo simulation and comparing with the experimental spectrum, we found that the proper value of Ec is in the energy range from 160 to 240TeV.
In this paper, the results of the time correlation have been given between optical signals and electrical signals in gas avalanche for both the Limited Proportional mode and the Self Quenching Streamer mode. There exists a weak optical emission simultaneously with the LP avalanche and the duration of the optical pulse is about 4ns at Vtr. The streamer development in SQS mode has a delay (a few ns) relative to the primary avalanche and there is a spread of delay of a few ns.
The cross sections for Ba(n, x)134Cs,134Ba(n, 2n)133Ba,140Ce(n, 2n)139Ce,142Ce (n,2n)141Ce and 23Na(n,2n)22Na reactions have been measured by the activation method relative to 54Fe(n,p)54Mn reaction in the neutron energy range of 13.50-14.80MeV. The measured results are compared with published data. Neutron energies are determined by the method of making cross section ratios of 90Zr(n, 2n)89m+gZr and 93Nb(n,2n)92mNb reactions.
Accelerator mass spectrometry has ultra-high sensitivity and can be used to detect extremely low impurity contents in samples. 10Be is a cosmogenic nuclide. As a tracker, it has been widely applied to earth, environmental and cosmographic sciences. 10Be is a pure β emitter with low end-point energy and long half-life.Therefore 10Be formation cross section can hardly be determined by the method of measuring the radioactivity of the product nucleus. This article describes a method to determine 10Be formation cross section by AMS technique and discusses the possible applications of AMS to other rare event measurements in nuclear physics.
The momentum distribution of multiparton system is derived from PQCD in Lund model, whileits color string configuration among parlous is assigned by phenomenological model. Using recursive formulation of matrix elements for e+e－→m (qq)+ng, the effective Hamiltonian is found and some of its properties are given as the basis for the study of color interaction and color string configuration among partons.
The process e+e－→J/ψ→V+X(JPC), X(JPC)→3P is studied using the generalized moment analysis method. The complicated structure of the resonance peak is discussed by use of multi-states coupling modes and some relations of moments are obtained. The coupling mode of the wide resonance peak can be determined by analysing the experimental data. The masses, widths and spins and so on of these states can also be determined.
In this paper, the general structure of the N=4 supersymmetric quantum mechanical system is given using the Clifford algebra. Some examples of its application are discussed.
Considering the arbitrariness for choosing vacuum wavefunction caused by unimodular condition, we replace the disconnected graphs by connected graphs and recalculate the values of μ0 and μ2. The results obtained are very satisfactory.
Using the three-fireball model, the multiplicity distributions for mean transverse momentum in hardon-hardon collisions at s=22GeV is investigated. We find that the change from negative to positive with increasing the transverse momentum cutoff comes from the following fact the rising scope of mean transverse momentum of hardon produced by side-fire balls with increasing the cutoff is greater than that of central fire balls.
The construction of a paired state of a quantum many-particle system is closely connected with its symmetry. There are three types of construction of paired state in axially symmetric deformed nucleus, i. e., monopole pair, ±Ω pair and signature pair, which are the eigenstates of (J2, J3), J3, and (J32, R1(π)), respectively.When only the pairing force is involved, the energy spectra of all three pairing Hamiltonian are identical. However, in the case of Cranked Shell Model, since the three types of paired states behave differently under space rotation, the energy spectra and the w variation of other relevant features differ to certain extent.
In the framework of quantum hadron dynamical theory(QHD), a more general relativistic Vlasov equation (RVE) is derived. Using this type of RVE, we study the isovector dipole giant resonances built on ground state in several spherical nuclei such as 16O, 40Ca, 90Zr and 208Pb. The main results show that the resonance energies for each nucleus are in good agreement with the experimental ones. Some arguments for our calculations are also given.
The microscopic structures of the ground and low-excited states of 12C are investigated via an analysis of symmetry based on the three α-cluster model. Some interested results are obtained.
The density dependent coupling constants of nucleon-meson interactions are adopted to incorporate the self-energy of relativistic Brueckner-Hartree-Fock calculations in the relativistic mean field approach. The density dependent interaction takes the N-N correlations into account. This density dependet interaction is employed to study the ground state properties of finite nuclei such as single particle levels, charge raddi and the binding energies per nucleon. The results calculated are in a good agreement with the experimental data. A comparison with the results obtained by other models is also presented.
The triangular crystal is used as monochromator on 4W1C beamline at Beijing Synchrotron Kadiation Facility. Three crystals of Si(111), Si(220) and Si(422) with an oblique-cut angle of 12.16° are employed at the same Bragg angle 23.65°to select monochromatic X-rays with wavelengths of 0.252nm, 0.154nm and 0.089nm,respectively. The triangular crystal is bent to a cylindrical shape to focus the beam in the horizontal direction and to provide focusing monochromatic X-rays for the diffuse scattering station. The theoretic calculations and SHADOW ray-tracing of the optical system are in good agreement with the experimental results.
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