1996 Vol. 20, No. 9
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The high-spin states in 198Bi have been studied with the 187Re(16O,5n)198Bi reaction at 16O energies between 85 and 105 MeV.In-beam measurements of γ-ray excitation functions γ-γ-t coincidences and γ-ray angular distributions were carried out with 6 BGO(AC)HPGe detectors and an intrinsic Ge planar detector.A level scheme of 198Bi with 26 γ-rays was established for the first time,and an 15+ isomer was determined with t1/2=8.0±3.6ns.Based on the known level systematics in 200—206Bi,the level structure in 198Bi was qualitatively interpreted.
Spin-polarized fragments 14B and 15B produced in the intermediate energy projectile fragmentation reaction were implanted in Mg single crystal,and the electric quadrupole moments Φ for 14B and 15B were determined by the β-NMR spectroscopy.The results obtained are |Φ(14B)|=29.84±0.75mb and |Φ(15B)|=38.01±1.08mb,which are compared with shell model calculations.
The ratio of factorial cumulant to factorial moment of multiplicity distributions in different pseudorapidity windows has been calculated by using the experimental data of multiplicity production for pp collisions at 400GeV/c.The results show that the ratio Hq exhibits an initial abrupt descent and then an oscillation around zero when the order q is increased.It is coincident with the PQCD prediction.The difference is that the position of the first minimum moves to higher rank when the pseudorapidity window becomes smaller.
Considered two dimensional self-dual fileds,the symplectic structure on the space of sloutions is given.It is shown that this structure is poincare invariant.The Lanrangian of two dimensional self-dual field is invariant under infinite one component conformal group,then this symplectic structure is also invariant under this conformal group.The conserved currents in geometrical formalism are also obtained.
The expression of the matrix element of the reflection matrix of Zn Belavin model is obtained.When it approaches the triangular limit,the non-diagonal reflection matrix of triangular statistical model is obtained.
Starting from the QGP kinetic equation,considered the perturbation of the color electric field of a moving test quark,the distribution function and the color electric potential of the quark in QGP are obtained using the method of the perturbation at the high temperature.The relation between the Debye Length λD or the screening mass ωD and the temperation T is discussed.The results at the rest state agree with the QCD theory.
The flow angles for the final state particles with five kind of mass number(A=1,2,3,4 and 5-8)are determined for 1.2 A GeV An+Au collisions at the Bevalac by minimizing the azimuthal anisotropy in the center-of-mass coordinde systems where the z axis is rotated to various polar angles in the reaction plane.The study of the polar angle distributions for the final state particles with different mass in the systems with the z axis rotated to the flow angles indicates that the degree of concentration around the flow direction and the now value increase with increasing mass number of the particles.
Relativistic correction is considered in the calculation of the heavy quarkonium properties in a thermal environment.The results are compared with the critical properties of QQ states predicted in non-relahvistic quark potential model.
Abstract:Using the closed time-path Green's function technique,we derived the relativistic Boltzmann-Uehling-Uhlenbeck(RBUU)equation for delta distribution function within the same framework used for nucleon's.In our approach,both mean field and collision term of △'s RBUU equation are given explicitly and simultaneously.The results show that the RBUU equation for delta and for nucleon are coupled with each other.
In the framework of Quantum Molecular Dynamics model the individual nucleon behavior(regular or chaotic)in the intermediate energy heavy ion reactions is investigated.The correlation between the nucleon behavior and the reaction fragmentation mechanism is analysed.The nucleon motion in the evolution process of a compound nuclear system showed regular behavior.The coexistance of the regular trajectories and the chaotic ones suggests that the regular regions in the interaction area embed in irregular ones,reflecting the fractal nature of the repellor,and indicating the existance of local stable potential generated by intermediate mass fragment.The appearance of more instable trajectories associated with the decreasing number of nucleon and small cluster emission.The chaotic nucleon motion began earlier than the time when the system may reach the region of mechanical instability characterized by equation of state of nuclear matter.
In the spectral range from 5keV to 6.5keV,absolute calibration of the quantum efficiency of the AXUV-100 silicon photodiodes(as the transfer standard detector)has been derived from the filled Xe total absorbing ionization chamber used as absolute detector at Beamline 4W1B of BSRF.The calibrated efficiency of the AXUV-100 silicon photodiodes is spread to soft X-ray range as the efficiency of the AXUV-100 has a fine linearity from 50eV-6keV.The flux spectrum from Beamline 3B1A and 4B9B has been absolutely measured by the AXUV-100.The sensitivities of some soft X-ray detectors for inertial confinement fusion have been measured with the second standard silicon photodiode (AXUV-100).The measured results of XRD(A1 cathode)are correspondent with ones of LLNL in error range.
The shielding for secondary neutrons has been estimated with the method presented by R.Madey et al.for the reactions of 0.6 and 1.2GeV/u 12C-ion on thick Cu target.The concrete shielding thickness of forward and lateral direction are 9.8,4.8m and 11.5,6.9m respectively when beam current of 0.6 and 1.2GeV/u 12C-ion are 1×1013 ions/s.
Abstract:Application of Moyer Model tor evaluation of shielding design of high-energy heavy-ion accelerators is presented.Selection of Moyer parameters and calculations of shielding thickness in conditions of point and extended beam losses were described.Methods of determination of roof shielding thickness on the basis of sky shine dose are given.The calculations are compared with some results of analogue Monte Carlo calculations.
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