The Reaction Cross Section and Neutron Removal Cross Sections of 17C

The reaction cross section, together with the one-, two- and three neutron removal cross sections, of ¹⁷C with the energy of 79A MeV on carbon target were measured using the radioactive beam line RIPS of RIKEN. The reaction cross section and the one-neutron removal cross section were analyzed within the frame of Glauber model. Both the analyses favor the dominant configuration of a ¹⁶C core (2⁺) plus a d_5/2 valence neutron for ¹⁷C. The work for the neutron-rich carbon isotope on the reaction cross section σ_R and the interaction cross section σ_I on ^{12C target are summarized.}     

Neutron Relativistic Phenomenological and Microscopic Optical Potentials

The experimental data of the neutron total cross section σ_t,nonelastic cross section σ_non and elastic scattering angular distribution σ_el(θ) for ten target nuclei ranging from ¹²C to ²³⁸U with incident energies E_n=20—1000MeV were used to optimize the relativistic phenomenological optical potential (RPOP) through automatic search of the best parameters by computer.In addition,a relativistic microscopic optical potential (RMOP) based on Walecka model were also used to analyze the same data and compare with the RPOP.
Through comparison between these two kinds of relativistic optical potential hints in improving both the RMOP and RPOP is indicated.     

TRIPLET TO SINGLET CONVERSION OF POSITRONIUM IN OXYGEN

Using a aerogel sample with introduced oxygen gas as a variable energy positronium source,the triplet to singlet conversion of positronium in the elastic and inelastic collisions between positronium atoms and oxygen molecules has been investigated with a time selecting energy spectrometer.We have found that the conversion cross section σ_0—p is proportional to 1/v for slow positronium in the elastic collisons,where v is the mean velocity of positronium,and for the inelastic processes,the cross sections are estimated to be σ_0—p=2.1×10^－17cm² and 6.6×10^－18cm² respectively at kinetic energies of positronium near two thresholds.     

Effect of f0(975) and φ(1020) Mesons on Neutron Star Mater

In the RMF approach, considering the contributions of the σ^* and φ mesons and the hyperons in the baryon octet {N,P,Λ,∑^－,∑⁰,∑⁺,Ξ^－,Ξ⁰}, the properties of neutron star matter have been investigated. It is found that with the contributions of the σ^* and φ mesons, the critical baryon density of hyperon appearance decreases, the number of hyperons increases, the transition density ρ_0H of hyperon stars decreases, the equation of state turns soft, the maximum mass of neutron star decreases and the corresponding radius increases, the central density, the central energy density and the central pressure are all reduced.     

MEASUREMENTS OF ANGULAR MOMENTUM EFFECT OF FISSION BARRIER

The fission cross sections and the evaporation residue cross sections for ¹²C+²⁰⁹Bi and ¹⁴N+Pb reactions were measured with the gold surface barrier silicon detectors and the mica nuclear track detectors.The critical angular momentum l_er was deduced from the measured evaporation residue cross section σ_er on the basis of the sharp-off model.The fission barrier with the particular angular momentum i derived from the condition Γ_f/Γ_n=1 at l=l_e The angular momentum effect of the fission barrier was studied experimentally.     

INFLUENCE OF THE NEUTRON NUMBER OF TARGET NUCLEUS ON CROSS SECTIONS OF PARTICLES EMISSION IN 12C+112,124Sn

The energy spectra and angular distributions of Li, Be, B particles emitted from the ¹²C+¹¹²Sn and ¹²C+¹²⁴Sn reactions at E_L=70.0MeV are measured. The angular distributions of the Li, Be, and B particles are found to be peaked around the grazing angle, without any forward peaked component.
The experimental results also showed that the cross section for emission is larger in ¹²C+¹¹²Sn reaction than that in ¹²C+¹²⁴Sn reaction, in contrast with the cross sections for Li, Be and B emissions. The indicates the effect of the neutron number of the target nucleus on the emission probability.     

Extended Glauber Theory and Its Application in Halo Nucleus Scattering

We introduced an extended Glauber theory for a halo nucleus scattering, where the halo nucleons and the nuclear core were treated separately. Expressions of reaction and interaction cross sections of the halo nucleus scattering were derived. We took the halo structure of the projectile nucleus into account and adopted an improved optical limit approximation. In the framework of the extended Glauber theory, we studied the reaction cross section for the halo nucleus ¹⁴Be scattering on a target ¹²C. For comparison, the reaction cross sections of ¹²Be+¹²C were calculated as well. The density distribution of target ¹²C is taken from experiments, and those of the projectiles ¹²Be and ¹⁴Be were obtained by two methods. One is that the harmonic oscillator wave functions for ¹²Be and ¹⁴Be are used. The length of harmonic oscillator is adjusted to reproduce the reaction cross section of ¹²Be+¹²C at the high energy E=790MeV/u . The density distribution of ¹⁴Be was also calculated self-consistently in the relativistic mean field (RMF) theory, with a long tail wave functions for the two neutrons in ¹⁴Be. It was found that the calculated reaction cross sections for ¹²Be+¹²C at E=790MeV/u and E=56.5MeV/u were in good agreement with the experimental data no matter harmonic oscillator or RMF wave functions were used. In contrast, the experiments of the reaction cross sections for ¹⁴Be+ ¹²C could only be reproduced when the wave functions of two 2s_1/2 neutrons spreaded over with a long tail. It comes to a conclusion that two outside neutrons in ¹⁴Be form a halo structure.     

Charged Top-Pions Corrections to the Top Quark Production at LC in TC2 Theory

We discuss the contributions of PGBs (technipions and top-pious) to the top quark production in TC2 theory at the high energy e⁺e^－ linear collider (LC) experiments. We find that the corrections to the production cross section σ_tt mathly come from top-pious. The corrections of the charged top-pious are significantly large in most of the parameter space. With reasonable value of the parameters, the correction to σ_tt can reach about 8% which may be detected at LC experiments.     

Continuous-wave laser properties of 4F3/2?4I13/2 channel in the Nd3+LiNbO3:ZnO non-linear crystal

This work reports for the first time continuous-wave laser action at room temperature around 1.3 7m in Nd³⁺ doped LiNbO₃:ZnO. Optical spectroscopy has been used to determine the main laser characteristics of ⁴F_3/2‘⁴I_13/2 channel, such as emission cross section and excited-state absorption cross section at laser wavelengths. Internal optical losses have been estimated from laser gain experiments. Under non-optimal conditions laser slope efficiencies of 30% have been obtained.     

Skyrme-Hartree-Fock Description of the Nuclear Structure in Ca Isotopes (Ⅰ)Binding Energy and Shell Effects,Radii and Density Distributions

The ground state properties of Ca isotopes far from stability line were systematically studied using the Skyrme Hartree Fock model.The shell effects on the binding energy and two neutron separation energy are discussed.The isospin dependency of the unclear radii and nucleon density distributions and the shell effects on these properties are also studied.It is shown that the neutron magic number affests the width of nuclear surface and the nucleon density distributions beyond the nuclear surface.The change of proton rms radii R_rms with neutron number excess I=(N-Z)/A follows R_rms=3/5(1+αI+βI²)r_pZ^1/3.The effect of the centrifugal potential on the nuclear density in the outer trach of nuclear surface is clearly shown.     

Initial State Interactions and J/ψ Production-Rate Suppression in High Energy P-A Collisions

The influence of the initial state intcractions on the J/ψ production-rate supression in p-A collisions is studied. The incident proton energies decrease due to the inelastic interactions with the target nucleus. Considering energy loss of the incident proton,the data are well reproduced by using the final state interaction cross section σ^f_abs=2.1mb.     

C(γ,η)X Reactions and Properties of N*(1535) in Nuclei

The η photon production reaction on nuclei is studied by employing N^*(1535) resonance model. The parameters of the model are extracted by using experimental data of N^* decay channels and fitting γp→ηp reaction cross section. The result shows that the theoretical values are in good agreement with experimental data if M_N*=1550MeV. The total cross section of the η photoproduction on ¹²C is calculated. We find that the width of N^*(1535) in nuclei increases because of corrections of many-body effects, and the interaction between N^* and nuclei has the feature of repulsion.     

Projectile Fragmentation in 46.7MeV/u 12C Induced Reactions

The projectile-like fragments emittd from 46.7MeV/u ¹²C induced reactions have been measured.The most probable energies of the PLFs due to the projectile fragmentation can be reproduced within the Abrasion picture.Their parallel momentum distribution widths are found to fulfill the Goldhaber relation and the extraced reduced parallel momentum distribution width σ₀ is 80±10MeV/c,which is close to the value obtained in the relativistic energy region.Futhermore,the values of σ₀ are the same for different reaction systems in our experiment.     

Q 2-Dependence of the Drell-Hearn-Gerasimov integral

The energy and four-momentum (Q²) dependence of the photo-absorption cross section on the proton is calculated for helicity у/2 and х/2 states. An effective Lagrangian model is used, formulated in terms of meson and baryon degrees of freedom, which obeys crossing symmetry, unitarity, Lorentz and gauge invariance. The difference in the cross sections for the two helicity states, the Drell-Hearn-Gerasimov integral I_DHG(Q²), is evaluated at different Q². We find that at small momentum transfer the absolute value of I_DHG(Q²) first increases to reach a maximum at Q² , 0.05 GeV² before decreasing at higher Q².     

A Simulation of Emitted Nucleons:An Extended BUU Model

On the basis of the old BUU method,the neutrons and protons of the projectile and target nucleus was distinguished,meanwhile,the droplet model which included the surface diffusion parameter,neutron skin and deformation parameter etc.was considered during simulating original nucleon's distribution.Condersing the fact σ_np≈3σ_nn≈3σ_pp in intermediate energy domain,it was incorapated into the collision term of BUU.Before studying 44MeV/A ⁸⁶Kr+¹⁹⁷Au reaction by the improved BUU model,the stability of the model has been checked,then the condition of nucleons emission was defined,finally the impact parameter dependence of the abraded neutrons and protons from the projectile was obtained,so was the correlation of TLF and PLF.     

MEASUREMENT OF ISOMERIC CROSS-SECTION RATIO IN 133Cs(n,γ) 134Cs REACTION

The isomeric absolute cross-section have been measured for the reaction ¹³³Cs (n,c) ¹³⁴ Cs at 14.8 MeV neutron energy.The results are:σ_n,γ^134mCs=1.76±0.14mb;σ_n,γ^134gCs=5.17±0.41mb;σ_n,γ^134+gCs=6.93±0.55mb.The isomeric cross-section ratio is σ^134m_Cs/σ^134gCs=0.34±0.03 The experimental results are in agreement with the values given by S.M. Qaim andcompared with the theoretical results calculated by Huizenga-Vandenbosch theory.From this, the spin cut-off paramenter σ and the number of γ-Cascades have been de-termined.     

17C反应截面的测量及其密度分布分析

在日本理化学研究所的放射性束流线上用透射法测量了能量为79 MeV/u的17C在12C反应靶上的反应截面；利用有限力程Glauber模型对17C的密度分布进行了分析. 同时拟合本实验结果及高能区的实验数据发现, 17C的中子密度分布中存在一个尾巴. 基于芯核加单粒子密度分布的假设,认为17C的价中子主要处于1d5/2轨道. We have measured the reaction cross section of 17C on a 12C target at 79 MeV/u using the transmission method. Together with previous data at high energy, we deduced the density distribution of 17C by fitting the experimental data using the finite range Glauber model. The analysis shows that a simple harmonic oscillator (HO) density is not adequate to explain consistently the present experimental data and the one at high energy simultaneously. To get a better fit of both the data, the existence of a tail in the density distribution of 17C is proposed. Based on the assumption of a core plus a single neutron, it is found that the valence neutron of 17C is mostly in the d orbital. This is in agreement with the conclusion from the measured momentum distribution.     

Estimate of the cross section for thermal neutrons

Cross section of the thermal neutrons is considered in the framework of the statistical approach to the complicated nuclei. The probability distribution ?(z = σ/σ*) to have given cross section σ (determined by fluctuations of resonance positions and widths), where σ* is the cross section for the model of equidistant resonances with the same width, has been calculated. The last quantity can be represented in terms of the neutron strength function for given nuclei. The probability distribution ?(z) is universal for all nuclei.     

On the Test of Pomeron Structure (Parton Distribution Functions)

The contributions of the double Pomeron exchange to the J/ψ production inhigh energy p+p(p) collisions are calculated using different models for parton distribution functions inside the Pomeron(P). For the Ingelman-Schlein model in which gluons dominate in partons, the cross sections in high energy increase smoothly with as In²S or InS. The total cross section σ(S) is about 10²－10³nb in the TeV energies. For the Donnachie-Landshoff model in which the P are considered as something like isoscalar photons with C=+1 the cross section behavior increasing with energy is a little bit complicated. In same energy range, the cross sections are only 1-3nb which are smaller than that of the former case by 2—3 order of magnitude. So, if we assume the parameters of the above models are reliable, then these J/ψ production processes should be a good place for testing these models.     

Study of Yields for Target Fragments From the Reaction of Iron With 80MeV/u 16O Ions

Produchon yields were determined for 25 abet fragments produced from the reaction of iron with 80 MeV/u ¹⁶O ions. From these data, charge distribution and mass yield distribution have been deduced. The experimental results are compared with those reported from our previous work. It is found that the width parameter σ_z and the most probable charge Z_p of the charge distribution increase slowly with increasing bombarding energy. The mass yield distribution is discussed in terms of the concepts of limiting fragmentation and factorization.