1997 Vol. 21, No. 1
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The light charged particle emission in coincidence with fragmemts in 10.6MeV/u 84Kr+27Al collision is studied.Emphasis is laid on the characters of two-order anisotropy coefficient of Fourier expansion up to two order from fitting particle azimuthal distribution and particle-particle azimuthal correlation.The derived results prove that particle emission is statistically independent with the same azimuthal distribution in each event.It is found that two-order anisotropic coefficient depends weakly on the fragment mass and increases with increasing emitted particle mass.
The structure,operation principle and performance of the bi—dimension position sensitive avalanche chamber (BPAC) used in the study of fusion fission induced by heavy ions at the near and sub-Coulomb barrier energy region are describerd.
The fold angle distribution of fragments in different angle region for 84MeV(Ecm)16O+232Th reaction system was obtained by using BPAC,from which the angle distribution of transfer—fission fragments has been distinguished from that of compound mucleus fission fragments.It is thereby certified that transfer—fission is not the reason of anomalous anisotropies of fragment angle distribution.Meanwhile experimental results supported the preequilibrium fission model,in frame of which the anomalous anisotropies of fragment distribution was explained.
Excitation function fluctuations for projectile-like fragments from 19F+51V dissipative reaction within the energy region of 102.25—109.50MeV are reported.The statistical method is applied to the analysis of energy coherence in the cross rection fluctuations and the strong cross correlation between exit channels is obtained.The dependences on charge number and on mass number are presented.The relation between angular velocity damping and the rotational energy dissipation is discussed.
The results of experimental studies on eadiation damage of CsI(Tl) crystal were reported.There are radiation damage effects on CsI(Tl) crystal.Experimental studies on recovery of damaged CsI(Tl) crystals were made.It seems that after heating at 200℃ for 4 hours,the damaged crystals could be recovered completely.
The oscillator algebra with reflecting boundary is constructed together with its Fock space,and is generalized to the cases with generalized statistics and multicomponent.Such oscillators depend manifestly on the reflection factor and the statistical(exchange)factor.By construction,the Fock space of such oscillator algebras can be obtained by certain projection operation.from that of the usual bosonic oscillator without reflection condition.
Based on the phase-space generating functional of a system with a singular Lagrangion,the Ward identities under global transformation in phase are deduced.The quantum conservation laws under the global symmetry transiormation are also derived which is in general different from classical Hoether's ones.The preliminary application of our formulation to the Yang-Mills theory the Ward-Takahashi identity and BRS conserved quantity for BRS transformation are presented.Applying to non-Abelian-Chern-Simons theory the quantum conserved angular momentum (QCAM) are obtained.The QCAM differs form classical one because the former needs to take into account the distribution of angular momentum of ghost innon-Abelian-Chern-Simons theory.
Incomplete-Fusion-Fragmentation Model is used to analyze the multifragmentation of the projectile remnant in 600MeV/u Au+Au reaction.The theoretical resultsof the mass number,the excitation energy and the thermodynamical temperature of the projectile remnant agree well with experimental data.The backbending structure in the curve of temperature as a function of the excitation energy per nucleon,i.e. the evidence of liquid-gas phase transition,is reproduced and reasonably related to the decay modes phase transformation from dominance of the multifragmentation mode to the vaporization mode.
Using hydrodynamical model of transverse expansion,we investigate the transverse momentum distribution of the final state π on 16O－Au collisions.When the constituent influence of the gas is taken into account the calculated result fits the NA35 data better than that of D.Knsnezov's.
In order to study the dynamics of symmetric fission,the inertia tensor is computed based on towpara meter generaelzed Cassinion oval curve dropter model and the assumiption that nucleus is an irrotational and incompressible fluid.
An improved formulation of the pairing correlation was proposed by introducing a radial correlation factor to reflect more reasonably the short range character of the correlation in nuclei.The experimental fact that the ground state band of 157Tm is built on the Nilsson orbit 1/2+ is explained naturally.
A laser driven photoemissive high-brightness electron source at Peking University is reported.Through a DC accelerating gap of 100kV voltage,the device is capable of delivering high-brightness electron beam of 35—100ps pulse duration when irradiated with a mode-locked YAG laser.The geometry of the gun is optimized with the aid of simulation codes EGUN and POISSON.The results of experimental studies on ion implanted photocathode and cesium telluride photocathode are given.The proposed laser driven superconducting RF gun is also discussed.
This paper describes and demonstrates the scaling law in the lattice design of a storage ring.When the size of the storage ring are enlarged or reduced according to a scale,the operating point ν and the beam emittance ε will be invarible.But while the energy of the storage ring is changed,the emittance will vary with the energy square.
The radiation field around the National Synchrotron Radiation Laboratory (NSRL) is a directive prompt one.It is significant to monitor it and study its characteristics.This paper introduces the monitoring method and results.
The hadronic decays ψ(2S)→ρα2 and K*0K2*0+c.c. have been studied in a sample of 3.6×106 ψ(2S) events.Measurements of their branching fractions are presented.Both channels violate the “15% rule” predicted by perturbative QCD compared with the corresponding J/ψ decays.These results serve as new examples of abnormal suppression of ψ(2S) decays into vector-tensor final states that was first observed in ψ(2S)→ωf2
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