1996 Vol. 20, No. 12
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The total width of the χc0 was determined by analysing γπ+π－ and γK+K－ final states of ψ(2S) decays based on 3.5 million ψ(2S) events produced from the BES detector at BEPC.The Monte Carlo simulated mass resolution,being normalized by that determined experimentally at the χc2,is used in fitting the observed signal of the χc0 and thus results in a best estimate of the total width of χc0,Γχc0=(15.0+3.2－2.8)MeV.Improved values for the branching fractions of χcJ going to π+π－ and K+K－ are found to be B(χc0→π+π－)=(4.27±0.23±0.60)×10－3,B(χc0→K+K－)=(3.44±0.21±0.47)×10－3,B(χc2→π+π－)=(1.52±0.17±0.29)×10－3 and B(χc2→K+K－)=(5.2±1.1±1.8)×10－4, respectively.
In recent years,some short time enhancements of cosmic ray paticles during large solar flares(GLE)were recorded by neutron monitor at sea level and underground muon detector at different depths.The energy regions concerned were in several hundred GeV,even in few TeV.It is disccused in this paper,that the flux enhancemengt in TeV region may be due to the re-acceleration of the galactic cosmic rays in the period of large solar flares.Because of the very steep energy spectrum of cosmic rays,if only 10% cosmic ray paticles are re-accelerated with energy increment of several hundred GeV,the cosmic ray flux in TeV region could increase considerably.
The off-line calibration system for sub-detectors of BES,including main driftchamber,time of flight counter,shower counter and muon-identification counter,is described.The detector performance during the period of Ds physics runs in 1994 and results of data quality check are presented.
The Nodvik and Holstein-Primakoff realizations for the two-parameter deformed quantum algebra SU(1,1)q,s are given.The deformed mappings between SU(1,1)q,s and a two-parameter deformed oscillator are also presened.
The nuclear spin of grotmd state in 157Tm is I=1/2 This spin may be explained by a non-axisymmetric quadruploe deformation γ of 157Tm The recent experiment of EC/β+ decay of 157Yb does not support this explanation. However,thenon-axisymmetric property of 1/2+ band in 157Tm is confirmed by our systematic analysis of 1/2+ rotational bands in odd-A Tm nuclides.
The isospin-dependent symmetry energy,Coulomb energy and nucleon-nucleon cross sections are considered in the quantum molecular dynamics model. The influence of isospin effects on the emission of nucleons is discussed in the head-on collisions of the system 40Ar+40Ar at the incident energy of 25 MeV/u.It is observed that the ratio of neutron to proton of pre-equilibrium nucleons is higher than that of the reaction system and the symmetry energy enhances the emission of neutron but reduces the emission of proton,at the same time,that the isospin-dependent nucleon-nucleon cross sections favour the emission of both neutron and proton,but they seem to be more beneficial to the emission of proton.
In this paper,the influences of charge carrier concentration(n),mobility and temperature on vacancy concentration(Cd)were studied by positron annihilation in Inp doped with sulphur.The mechanisms of the influences of charge carrier concentration,mobility and temperature in vacancy are discussed.The types of vacancy are discussed too.
A new method using synchrotron radiation source to measure the fluorescent decay properties of inorganic scintillator is introduced here.Using this method the pure BaF2,CeF3(crystal and powder),BaF2 doped with Ia3+、Ce3+ crystals were measured.The results indicate that the slow component of fluorescent decay of BaF2 is suppressed to a certai extent by doping of La3+ or Ce3+.However,for these BaF2 scintillators doped with two kinds of impurities,the mechanism of suppression of slow component are different.
In order to make the concept design of the axial position and the rotation angle of the stripping target of type CYCIAE cyclotrons,the optical property of H－ ion stripped has been investigated. By using the program CYCTRS,the positions of stripping points for the beam with different energies have been calculated and compared with practical positions of CYCIAE30 to show that the theory and the method used in calculation are reasonable.Also,the optical property of the H+ beam in space Under the fringing magnetic field of the cyclotron is investigated.Then,the positions of stripping points for the beam with different energies of CYCLE70 are determined.
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