1999 Vol. 23, No. 4
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Using the data of the Sun's shadows for the 10 TeV cosmic ray flux, which are obtained in the period of June 1990-August 1996 by the Tibet air shower array, the correlation betWeen the deviahons of Sun's shadows and the strength of the mean solar magnectic field at the same period has been studied. One simple model used to calculate and explain this relations is also presented.
The radioactive decay of 72Ga has been investigated by means of NaI-HpGe Compton-suppress spectrometer,and γ-γ coincidence measurements Performed with two HpGe detectors coupled to three-parameter(γ-γ-T) data acquisition system. 2.3×107 coincidence events are collected. A new decay scheme of 72Ga including 26 levels,87 γ-rays is established. The extensive coincidence relationships are used to identify the γrays and levels of 72 Ge, such as new γ-rays of 225. 92, 826.97, 1349.71,1475. 32, 1667.91, 2105.28, 2247.39keV and new levels of 3248.01, 3396.27, 3806.10,3864.56keV. The unsure transitions of 112.59, 937.97, 2402.25, 2939.95keV and level of 2939.83keV are confirmed in thes work. No evidence has been observed for the existences of 113.5, 1155.7, 1192.4keV γ-rays and level of 3707.1keV. The transitiou of 317.72keV γ-ray is moved from 3757.26-3439. 51keV level to 3565.85-3248.01keV level.
The angular distributions of intermediate mass fragments with Z=3-19 emitted in 30 MeV/u 40Ar+58,64Ni and 115In reactions over an angular range of 5°—140°have been measured.Exponential distribution function: dσ/dΩ=N·exp(-θ/a) was used tO fit the measured angular distributions.We have extracted the decay factor a that can be connected with the interaction time τ, and the factor N that is related to the intensity of the emission source.The relationships of a(Z) with Z and N(Z) with Z for different reaction systems and different angular ranges have been discussed. The dependence of angular distributions on isospin and the symmetry of reaction system have also been discussed.
The angular distribuhon in the range of 0cm=50°—90° and excitation funchon of the reachon products in heavy ion dissipahve reachon 27Al+27Al were measured, in the incident energy region from 114MeV to 120MeV with 200keV step. The statishcal property of the fluctuation of the excitation funchon in heavy ion dissipative reaction was discussed based on the integration of the macro outgoing channels.
Adopting connected graphs as independent graphs, the(2+1)-D SU(3) 0++ glueball wavefunction is calculated using scheme of truncating eigenvalue equations.
The Wilson fermion Condensates in 1+1 dimensional Lattice QCD are calculated by using the improved Hamiltonian and the variational method.The results are consistant with the predictions from continuum theory,and are almost independent of the Wilson parameter r. The three-links terms give important contribution to<ψψ> in the improved Hamiltonian theory.
in the scheme of Migdal-Kadanoff renormalization group transformation, the Phase structure of Z3 lattice gauge theory coupled with the Higgs field in four dimension space is studied.The phase diagram shows that among the three of the Higgs egion, confined region and free charge region,the first two regions are smoothly connected with each other.
According to our recent studies, we derive a new mass formula for strange quarks at zero temperatUre. We apply it to inveshgating the Propelles of strange quark matter and obtain similar results to those in the MIT bag model. A different point in our results is that the variation of sound velocity with energy density becomes a little slower.
A concept of copulative degree is Proposed in this Paper.Using the method of particle-group correlation's unction,the effects of the Particles with different correlative degrees on collective sideway now are studied for 1.2A GeV Ar+BaI2 collisions at the Bevalac stream chamber.Our studies indicate that correlative degree is an important parameter on describing collective sideward flow Properties. The minority of correlative Particles(or fragmentS) with larger correlative degrees can produce the effect arising from the collective sideward now, but the effect arising from high-order collective flow correlations can not be dominated by these minority of Particles (or ragments).It is results from the collective contribution of the majority of collective particles(or fragments) with various correlative degrees.
Considered the Drell-Yan background,the rapidity dependenec of the dilepton production in the baryon-rich quark-gluon matter from 197Au+197Au cental collision has been studied based on a relativistic hydrodnamic model. It is found that the dilepton yield is strongly suppressed with increasing rapidity.Such a characteristic signaling the formation of the baryon-rich quark-gluon matter can be tested in future experimentS at CERN and Brookhaven.
In this paper the nuclear structure of hypernucleus 5ΛHe and its effect on the binding energy BΛ of A hyperon are systematically studied. The Polarization effect of the core a is explored. The binding energy BΛ of 5ΛHe including D-state mixing component is calculated. The results show that the core α suffers a serious distortion by the interaction with Λ hyperon and has no longer the structure of a free Alpha Particle. The D-state mixing can improve the BΛ calculated value about 0.5MeV. A Possible three cluster structure is further explored. The Λ+d+d model can give a BΛ value close to the experimental one. The further exploration is necessary.
A lattice with negative momentUm compaChon faCtor (αp<0) for a tauchann factory is proposed and stodied. The bunch length at the designed currnt by simulation is shorter than the naed rms bunch length, that aught be an advantage for adophng the αp<0 lanice in colliders.
For the Proposed Lanzhou Heavy ion Cooler Storage mug (HIRFL-CSR), stochastic cooling is studied tO improve the beam quality and increase the luminosity. The longitodinal stochastic cooling Process of a stored beam with Palmer method is simulated,based on the Fokker-Planck equation. Optimum gain is obtained and applied during the simulation with the designed hardware Parameters. The resultS are discussed.
Under the interaction of incident proton with 150 MeV, the neutron yields and spectrum of the lead spallation target, as well as the radiation activity deposited on the target,are studied by means of SHIELD code.
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