1996 Vol. 20, No. 1
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The energy response characteristics of the barrel shower counter (BSC) of BES in energy region of J/ψ and Ds has been analysed,and a good energy linearity of BSC successfully obtained after eliminating the overlapping effect of the deposited energies in BSC of electrons and radiative photons.This demonstrates that the energy linearity of BSC is credible.
Particle-particle correlation functions have been measured for 40Ar+197Au collisions at E=25 MeV/u.Emission time of light particles has been extracted from correlation functions using the three-body trajectory model.The average emission time varies with the energy of particles. It decreases from about 300 fm/c for low energy particles to about 100fm/c for energetic particles.
By using off- line γ-ray spectroscopy in conjunction with thick target-thick catcher foil techniques,the mean forward recoil ranges have been measured for the residues produced from interaction of copper with 20—46MeV/u 12Cions.From these data,linear momentum transfer for central collisions has been extracted. The linear momentum transfer per incident nucleon attains a maximum value of 155MeV/c at approximately 27.5MeV/u.The maximum excitation energy of the composite system is found to be 2.5MeV/u.
The yields of known hafnium isotopes produced in 6.3-24.6MeV/u 40Ar+natW reactions were determined by γ-ray spectroscopy following radiochemical separations.The excitation functions,FW values and isotope distributions of hafnium were obtained.It is indicated that synthesis of new heavy neutron-rich isotopes is possible through the reactions induced by heavy ions at HIRFL energy region.The thick target is favorable for increasing the yields of neutron-rich nuclides far from the β-stability. However, further increasing incident energy is not always helpful to synthesize neutron-rich isotopes.
A big muon sample with wide momentum range is obtained by a time correction procedure applying to cosmic ray events collected by Beijing Spectrometer.The sample has been used in Ds Physics analysis.
Spectra and angular distributions of the(α,d)reactions on 56Fe 57Fe and 59Co have been measured with the △E-E telescopic systems and Q3D magnetic spectrometer at a bombarding energy of 35MeV from the HI-13 Tandem,and analyzed with microscopic DWBA.Among the angular distributions of nine levels strongly populated by 56Fe(α,d)58Co reaction, the experimental data of 6.79MeV and 6.4MeV levels in 58Co were analyzed and discussed. The highest stretched configuration (1g9/2,1g9/2)9 was found and Jπ=1+ of 6.4MeV level was determined for the first time. No isolated stretched states were observed by 57Fe 59Co(α,d)reactions.This probably means that the strength of the stretched configuration spreads on a number of states.
A two-parameter deformed two-dimensional interacting boson model with Uqp(U3) Uqp(U2) Uqp(SO2)symmetry is constructed.It is found that the energy spectrum and transition matrix elements depend very sensitively on the second parameter of deformation.
The processes J/ψ→X+f0 (980), X→K+ K－,f0 (980)→π++π－ are discussed using the generalized moment analysis method. It is suggested that in terms of the obtained moment expressions the spin-parity of the boson resonance X can be determined by further measurements.
With the aid of generating-functional technique and in the framework of correlation dynamics,we establish the constrained correlation dynamics of QED in the temporal gauge and canonical quantization form,and obtain a closed set of equations of motion for correlation Green's functions.
In this paper,the glueball mass of 0++ is calculated in the (2+1)－D SU(2) lattice gauge theory with connection graphs.The result shows a good scaling behavior.
Charged particle multiplicity distributions for e+e－ annihilation are shown to be very well described by a negative binomial distribution in high energy collisions.The factorial moments F2,F3 and F4 are given in terms of 3k.
The self-affine α-model in 2-dimensional phase space is discussed in some detail.The analytic expression of the normalized probability moments,C2N and C3N,are deduced for the self-similar analysis of a self-affine fractal object with Hurst index equal to 0.5.The Levy stability indices for both the self-similar and the self-affine analyses of 2-D self-affine model are calculated. The result of Monte Carlo simulation is shown to be consistent with that of analytic calculation.The recent experimental data from NA22 collaboration are explained qualitatively.
Starting from cranking shell model,a collective vibrational and rotational Hamiltonian(cranking Bohr-Mottelson Hamiltonian CBMH)is derived,in which the rotational frequency is not quantized.Introducing a reasonable collective potential,the formula for the rotational spectrum can be obtained.The formula is applied to analyze the rotational bands of even-even nuclei with satisfactory results.
Properties of the low-lying positive-parity states in 157,159Tm are investigated ly using the triaxial rotor plus particle model with the variable moment of inertia (VMI) of the core.The good agreement between theory and experiment shows that 157Tm and 159Tm may be triaxiality.Furthermore,it is suggested that an excitation rotational band in 157Tm probably already exists in the experimental data.
A 3-fermion system with spin S=1/2is examined.It is found that the quantum mechanical symmetry plays a decisive role in determining microscopic structures.
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