Vacuum Corrections for Nuclear Matter in Weak Momentum Dependence of Self-Energy

-The contributions of vacuum fluctuations to energy density in a weak momen-tum dependence of self-energy are calculated in Walecka model.After adjusting modelparameters and introducing momentum dependent form factors at meson-nucleonvertices to reproduce the empirical nuclear matter saturation properties,Hartree-Fockresults including vacuum effects at low to moderate densities are similar to those in therelativistic Hartree approximation.

Free-Energy and Emittance Growth Caused by Bunched Beam with Nonuniform Distributions in Both Longitudinal and Transverse Directions in Linac

The nonlinear space charge effect of bunched beam in linac is one of theimportant factors that induces the emittance growth due to the conversion of thefield energy to kinetic energy. Using a cylinder model of space charge in a linac,we derive the internal energy for a bunched beam with some nonuniform spacecharge distributions, such as Gaussian, waterbag and parabolic distributions inboth the longitudinal and transverse directions. And the emittance growth causedby these nonuniformities is worked out.

Equilibrating in Intermediate-High Energy Nuclear Reaction

The equilibrating problem for intermediate-high energy reaction is studied by themicroscopic kinetic model.The calculations are carried out for reaction 830 MeV p+Fe.Thetime evolution of the squared momentum components and the kinetic energy density shows thatquasi equilibrium is reached.

TMF-IMPAD Spectrometer

A transient magnetic field-ion implanted perturbed angular distribution spectrometer has beenset up at CIAE HI-13 tandem accelerator.This spectrometer is used to measure y-factors of high spinstates with lifetime of pico-or subpico-seconds.The 9-factors of the high spin states in 83y,84Zr and87Nbhave been successfully determined with it.

Properties of Hot Nuclear and Neutron Matter In a Relativistic Hartree-Fock Theory

Relativistic Hartree-Fock equations are derived for an infinite system ofmesons and baryons based on thermo field dynamics and Walecka’s model.The proper-ties of nuclear and neutron matter are studied for various temperatures and densities.

Space Charge Effect of Bunched Beam With Gaussian Distribution

The nonlinear space charge effect of a bunched beam with Gaussian distribu-tion in the longitudinal direction is discussed.Some useful formulae are derived for cal-culating the potential induced by a cylinder model of space charge in the waveguide of alinac with different combinations of density distribution:Gaussian distribution in thelongitudinal direction versus Kapchinskij Vladimirskij,waterbag,parabolic andGaussian distribution in the transverse direction,rcspectively.

Space Charge Effects of Bunched Beam with Nonuniform Distribution in Both Longitudinal and Transverse Directions

The nonlinear space charge effect of bunched beam with nonuniform densitydistribution in both longitudinal and transverse directions is discussed.Some usefulformulae are derived for calculating the potential induced by a cylinder model of spacecharge in the waveguide of a linac with longitudinal density distributions of waterbag(WB) or parabolic (PA) type combining with transverse density distributions ofKapchinskij-Vladimirskij (K-V).waterbag,parabolic and Gaussian (GA) types,resepectively.

Optimization of Gas Mixture for High Pressure Gas Scintillation Drift Chamber

The new experimental results of optimum gas mixture for High Pressure GasScintillation Drift Chamber(HPGSDC)are briefly presented.The features of the charge am-plification and the photon scintillation are investigated with different concentration of Ar in Xeand the anti-Penning effect is discovered in this case.This is useful for future experiments inHPGSDC.

Negative Drive of γ Deformation in Rapidly Rotating N=88,90 Nuclei

In the N=88,90 region,a strong negative drive of γ deformation is generatedby the second lowest positive signature vi13/2 quasiparticle orbital.In contrast,thelowest positive-parity and negative-parity orbitals in this region exhibit positive drivesin the γ deformation toward oblate shapes.Replacing one of these with the negativedrive orbital strengthens the collectivity for the side band configurations at very highspins.

Emittance Growth Caused by the Transverse Nonuniform Space Charge Distributions of Bunched Beam in Linac

The nonlinear space charge effect of bunched beam in linac is one of the im-portant factors that induces the emittance growth due to the conversion of the field en-ergy to kinetic energy.In this paper,the internal field energies associated with sometransverse nonuniform space charge distributions of a bunched beam,such as Gaussiandistribution,waterbag distribution and parabolic distribution,are worked out.And theemittance growth caused by these nonuniformities are obtained.

Angular Momentum Dependent Exciton Model

To consider the angular momentum and parity conservation the angular mo-mentum (J) and parity (π) should be addressed in the master equation of the excitonmodel.Therefore the internal transition rates and the emission rates must be Jπ depen-dent.The angular momentum factor of the internal transition rates is given and the an-gular momentum conservation effect is discussed.

Effect of Preequilibrium Fission on Fragment Spins

The fission angular distributions and the angular dependence of fragment spins in ter-ms of preequilibrium fission model are calculated.The results show strong effects of preequil-ibrium fission on both angular distributions and angular dependence of fragment spins.

Excitation Functions for Reactions Induced by Deuteron in Iron

Excitation functions are measured for the products of 55Co,56Co,57Co,58Co,52Mn and 54Mn nuclides by deuteron induced reactions in natural iron in bombardingenergy range below 20 MeV.The stacked activation foil technique is used to carry outthe measurements.The γ-ray spectra of individual foils are determined using a Ge（Li）detector.

Exciton Model of Two-Fermion System

The two-componenl exciton model is applied for calculating the data ofnucleon induced reactions.The angular momentum and parity conservations are takeninto account.In terms of the calculated results of n+56Fe at En=14.5 MeV the physicalpicture of the two-component model has been analysed.

Systematics of Isomeric Cross Section Ratio for(n,t)Reaction at 14.6 MeV

On the basis of Hauser-Feshbach theory and some approximations,parametrized formulae of isomeric cross section ratio including two adjustableparameters for(n,t)reaction at 14.6MeV are derived.By fitting these formulae to theavailable measured data,parameters are obtained and the systematic behaviour of theisomeric cross section ratio are studied.The isomeric cross section ratio predicted by thepresent work is in good agreement with the limited measured data.

Level Spin Assignment Of Superdeformed Bands for A～190 Region

Using the expression of level energies of rotational bands and least-squares fitto cascade gamma transition energies of superdeformed bands,level spins of 27superdeformed bands for 13 nuclei in.4～190 region are assigned and compared withthose of others.

Quadrupole Pairing Correlations and Moments of Inertia of Superdeformed Nuclei

The Harmonic OseiUator Quadruple Pairing Cranking Hartree-Fock-Bogoliubov（HFB）theoreti-cal model is established and applied to the superdeforrned（SD）rotational states.The reduction and col-lapse of the pairing fields,including Y20,Y21 and Y22 fields at superdeformation and high spins,are stud-ied.It is found that the correct rotational frequency ω-dependence of the pairing fields is crucial for thetheory to reproduce the rising behavior of dynamic moment of inertia J（2） observed in the A=190 region,and the Y21 pairing contributes significantly to reducing the rising rate of J（2） and thus may strongly influ-enee the collective properties of SD nuclei.The calculated J（2） of 192H8 is in good agreement with the ex-perimental data up to （?）ω=0.32 MeV.

Secondary Extinction in Large Single Crystal

Universal expressions for the secondary extinction factor in X-ray andneutron crystallography are developed,based on an exact solution of the power transferequations using three dimensionless parameters.As a demonstration of the feasibility ofthese expressions,the long-debated problem of diffraction in a large lithium fluoridesingle crystal is reanalyzed by using Lawrence’s data set,with all the hitherto omittedstrong reflections (Y down to 0.20) included,and a R factor value of less than 0.014 isobtained.

Probing the Non-equilibration Component of Tilting Spin Mode

-The probabilities PNCNE of non-equilibration component of tilting spinmode have been extracted from the experimental fragment anisotropies for thesystems of 16O+232Th,19F+232Th,and 16O+238U.It is found that as a function ofBf（〈L〉）/Tsad,the values of PNCNF observed experimentally and expected on the ba-sis of fission before equilibration model have opposite trends.

Calculation of Gamma Production Data From Neutron Induced Reactions on Thirteen Targets

A semi-empirical method for the calculation of gamma production data ispresented and the calculations for gamma spectra and multiplicities from neutron in-duced reactions on thirteen targets are carried out.