Study of Mutagenic Effects of M_1 Generation of Maize Seeds Irradiated by Heavy Ions

In order to study M_1 biological effects induced by heavy ion irradiation on maize seeds, the embryosof dry maize seeds are irradiated with ~7Li and ~(12)C ions. The experiment is performed at the heavy ionscanning tube of the HI-13 tandem accelerator. The beam goes through a thickness of 25μm. Then themaize seeds are irradiated in the air uniformly. The linear energy transmission of ~7Li and ~(12)C are 120 and     

Study of Optical Potential of Weakly Bound System ~7Li+~(63)Cu

正The angular distributions of the elastic scattering of weakly bound nuclear systems of~7Li+~(63)Cu were measured at energy around the Coulomb barrier,to extract and study the optical model potential(OMP)of this weakly bound system.For the weakly-bound nucleus ~7Li,there are large amount of elastic scattering data.However,     

Search for the Halo Effect in the ~1H(~6He,~6Li)n Reaction

The experiment is carried out using the secondary beam facility of the HI-13 tandem accelerator at China Institute of Atomic Energy, Beijing. The experimental setup is similar to the previously illustrated. A 7Li beam with energy of 44 MeV from the tandem impinged on a D2 gas cell at pressure of 1.5×105 Pa, in which 6He ions are produced via 2H(7Li, 6He)3He reaction. The front and rear     

Progress on Measurement of Neutron Capture Cross Section

In recent years,neutron capture cross sections of Ag,Hf and W relative to that of Au in the energy range from 10 to 100 keV have been measured withtime-of-flight method.Kinematically collimated neutrons were produced by ~7Li(p,n)~7Be reaction with the pulsed 2.5MV Van de Graaff accelerator.Captureevents were detected by two Moxon-Rae detectors.The resolution time of thewhole system,that is,the full-width at half-maximum(FWHM)of the promptgamma-ray peak was 1.60 ns.The total uncertainty is about 7% for most of thedata points.     

Comparison between nuclear thermometers in central Xe＋Sn collision

The temperature of fragmenting source in central heavy-ion collisions at Fermi energy is investigated by the isospin-dependent quantum molecular dynamics model in combination with the statistical decay model GEMINI. Five different nuclear thermometers are used to extract nuclear temperature. We find that the He and Li isotope temperature reaches a plateau at about 70-100 MeV/nucleon of beam energy. The slope temperature and the quadrupole fluctuation temperature give high values. The quantum slope temperature and the quantum quadrupole fluctuation temperature are more close to the He and Li isotope temperatures.     

Calculations of the Gamma Energy Spectra from Neutron Radiative Capture Reactions for ~(197)Au

The aim of this paper is to theoretically explain the abnormal protuberances near and above 5.5 MeV in the gamma spectra of the (n,γ) reactions of the nuclei within the nuclear mass regions from 110 to 140 and from 180 to 210, respectively. Supposing that in the primary and cascade gamma de-excitation processes of the compound nucleus, in addition to the giant dipole resonance model, there exist the de-excitation processes of the excited states of ~6He, ~6Li, ~6Be, ~7Li and ~7Be particle cliques, for which the gamma-ray strength function was developed. The (n,γ)reaction cross sections and the gamma energy spectra at the neutron incident energies from 0.01 MeV to 3 MeV for ~(197)Au were calculated and the results are in better coincidence with the experimental data. Especially for the gamma energy spectra, the abnormal protuberances near and above 5.5 MeV were reproduced very well.     

DETERMINATION OF THE SURFACE BINDING ENERGY OF A Cu/Li ALLOY BY MEASUREMENTS OF ANGULAR DISTRIBUTION OF SPUTTERED ATOMS

A copper based binary alloy containing 16.9 at % lithium has been bombarded with deuterium ions in energy range of 400 eV to 2 keV at the incidence angles of 70° and 80° away from the surface normal. The sputtered flux was condensed on Al- strips arranged arround the target in a cylindrical cup. 1.5 MeV proton backscattering and nuclear reaction 7Li(p, α)4He were used to detect the collected atoms of Cu and Li simultaneously. The angular distribution of sputtered atoms has been shown to be different for two components and strongly anisotropic for the grazing incidence. According to direct knock-on sputtering model and the experimental results the angle for the maximum differential sputtering yield is dependent on the incidence angle α, the bombarding energy E, the energy transfer factor γ= 4M1M2/(M1+ M2)2 and the surface binding energy U. With the assumption that the sputtered particles are diffracted by a planar barrier the surface binding energies of 2.3 eV for the Li component and 3.0 eV for the Cu component have been determined by fitting the measured angles of preferred ejection to the direct knock-on sputtering model, and the results agree well with a pair-binding model.     

CALCULATIONS OF NEUTRON ELASTIC AND INELASTIC SCATTERING FROM~7Li

The fast neutron elastic scattering from ~7Li have been ana-lysed by means of the optical model.It was found that it is neces-sary to decrease the real-well diffuseness slowly with increasingenergy.The microscopic DWBA were used to calculate neutroninelastic scattering by ~7Li to the excited states at 0.478 MeV and4.6 MeV.In the DWBA calculation,some parameters have beenchosen as energy dependent parameters in order to improve the computation.     

Preliminary Evaluation of the Adequacy of Lithium Resources of the World and China for D-T Fusion Reactors

This paper studied the adequacy of the World and China lithium resources,consid-ering the most promising uses in the future,involving nuclear fusion and electric-vehicles.The lithium recycle model for D-T fusion power plant and electric-vehicles,and the logistic growth prediction model of the primary energy for the World and China were constructed.Based on these models,preliminary evaluation of lithium resources adequacy of the World and China for D-T fusion reactors was presented under certain assumptions.Results show that:a.The world terrestrial reserves of lithium seems too limited to support a significant D-T power program,but the lithium reserves of China are relatively abundant,compared with the world case.b.The lithium resources contained in the oceans can be called the "permanent" energy.c.The change in 6 Li enrichment has no obvious effect on the availability period of the lithium resources using FDS-II (Liquid Pb-17 Li breeder blanket) type of reactors,but it has a stronger effect when PPCS-B (Solid Li 4 SiO 4 ceramics breeder blanket) is used.     

Tests of the GIC and Measurements of Angular Distributions and Energy Spectra for ~(58)Ni(n,p)~(58)Co Reaction at 4.1 MeV

On the basis of measurements of double differential cross sections for (n,α) reactions in 5-7 MeV neutron energy region using gridded ionization chamber (GIC), we constructed a new GIC which, compared with the old ones, can bear higher pressure and makes it possible to measure (n,p) reactions up to 6 MeV and (n,xα) reactions up to 20 MeV. To test the new chamber, the saturation property for argon and krypton mixed with a few percent CO_2 was studied using ~(241)Am and compound Pu α source and tritium from ~6Li(n_(th),t)~4He, and the two dimensional spectra for ~(241)Am and Pu α source, ~6Li(n_(th),t)~4He and H(n,p) reactions were measured. The measured energy spectra and angular distributions for α and tritium are reasonable, and the derived data for α, proton and tritium in argon and krypton from the measured spectra data were compared with the calculated ones. They are in good agreement. The angular distributions and energy spectra for ~(58)Ni(n,p)~(58)Co reaction at 4.1 MeV neutron energy were m     

Progress on Measurement of Nuclear Decay Data

1.The Studies on the Decay Scheme of 72.3-D ~(160)Tb (SunPunan Hu Dailing Ding Zhaozhong) The decay scheme of ~(160)Tb has been studied with Ge(Li)detector and 105cm~3 Ge(Li)-110 cm~3 HpGe coincidence system.Forty-one gamma rays havebeen observed.The energies(in keV)and relative intensities of gamma raysfirst observed in this work are 148.7(0.026),319.4(0.018),728.0(0.033),and 1125.0(0.007).Gamma ray with energy 239.7 keV reported in literatureis excluded.On the basis of these results,the decay scheme of ~(160)Tb has beenconstructed.Two excited states in ~(160)Dy at 1408.8 keV and 1694.1 keV havebeen proposed.     

Indirect Measurement of Cross Section of ^9Be（p,α）^6Li

The cross section of ^9Be（p,α）^6Li at low energies is important for nuclear astrophysics. But it is difficult for direct measurement because of the Coulomb barrier and electron screening effect. In order to measure the 9Be（p,α）6Li bare nucleus cross section at astrophysical energies, the Trojan Horse Method（THM） can be applied. The main feature of the method is that it allows to extract the energy dependence for the bare astrophysical S（E） factor at very low energies without any extrapolation, by measuring the cross section of an appropriate three body process.     

Global Phenomenological Optical Model Potential for ~6Li,~7Li,~9Be,~(12)C and ~(16)O as Well as Exotic Nuclei Projectiles

<正>The optical model is one of the most fundamental theoretical models in nuclear reaction theory.The key point of the optical model is how to give the optical model potential.The global phenomenological optical model potential for~6 Li,~7 Li,~9 Be,~(12) C and~(16) O projectiles are studied by simultaneously fitting theexperimental data of the reaction cross sections and elastic scattering angular distributions in the mass range of the target nuclei 20≤A≤209at incident projectile energy below 200 MeV,     

Bursty Behaviour of Turbulent Particle and Energy Fluxes in Edge Plasma of HT-7 Tokamak

High time resolution measurements of the electrostatic fluctuations and the turbulent particle and energy fluxes have been performed with a Langmuir probe array in the edge plasma in HT-7 tokamak. Bursty behaviour was observed in the time resolved turbulent fluxes with positive skewness and large kurtosis. The contribution of the large sporadic bursts to the transport losses were estimated. The analysis shows that the turbulent fluxes have different behaviour in different frequency domains and the probability distribution functions （PDFs） of the particle and energy fluxes present two distinct scaling ranges. All these are essentially consistent with the predictions of the self-organized criticality （SOC） model, though further studies are needed.     

Numerical Simulation of Radial and Angular Distribution of γ-Ray＇s Energy Deposition in Scintillation Optical Fibre

Angular and radial distributions of the energy deposition of γ-ray radiation in scintillation optical fibres are simulated and analysed using the Geant4 system. The results show a linear relation between the energy deposition and the radius of the fibres. The deposition is roughly inversely proportional to sinθ with θ the incident angle relative to the fibre axis. The results could provide corrections to the measurements of the scintillation fibres used in monitoring the γ-ray radiation.     

The Energy Balance of Plasma in a Coaxial Plasma Opening Switch

The two-dimensional energy balance in a coaxial plasma opening switch （POS） is studied based on the single-fluid magnetohydrodynarnic （MHD） equations coupled with the generalized Ohm＇s law. The energy transfers between the plasma and the magnetic field are considered during the penetration of the magnetic field as the Ohmic heating is included in the energy-balance equation. The focus is on the energy partition between the magnetic-field energy and the dissipated magnetic-field energy in a high-density POS with different rise-in-time electric currents at the generator boundary. The simulation code is tested in two cases： the constant-in-time current case and the linear rise-in-time current case. For the sinusoidally rise-in-time current similar to that of the experiments, it is shown that at the end of the conduction phase the dissipated magnetic-field energy is 36.5% of the input electromagnetic energy, which is consistent with the experimental results.     

The extraction and smoothing algorithms for γ-ray spectrum of a CdZnTe detector system

The extraction algorithms for pulse amplitude and smoothing of energy spectrum have a great influence on energy spectrum of γ-rays during the digital detection and analysis procedure. For a CdZnTe digital γ detector system, different extraction algorithms for pulse amplitude and smoothing of energy spectrum are discussed in this paper. The results show that extraction of pulse amplitude using the first-order derivative method and smoothing of energy spectrum using the wavelet transformation method may obtain energy spectrum with good performance.     

New Measurement of Proton Transfer Reactions and Elastic Scattering for 7Li + 13C at 34 MeV

The 13C(7Li, 6He) 14N reaction is measured at E(7Li) = 34 MeV with the Q3D magnetic spectrometer of HI-13 tandem accelerator. Angular distributions at forward angles for proton transfer to the ground and the first excited states in 14N are obtained. In addition, angular distribution for 7Li + 13 C elastic scattering is also measured. The optical potential parameters for the entrance and exit channels of the transfer reactions are derived by fitting the 7Li + 13C and 6Li + 14N elastic scattering experimental data, and their angular distributions are well reproduced by the distorted wave Born approximation calculations. A phase shift of about 2 between the calculations and the experiment data has been found in the earlier (7Li, 6He) study, whereas no such phase shift is observed in the present work.     

Neutron Skin Thickness of Nuclei and Effective Nucleon-Nucleon Interactions

The Skyrme energy density functional is applied to study the ground state properties of nuclei and the stiffness of the symmetry energy. The binding energies and charge root-mean-square radii for selected nuclei can be described well. This makes us able t…     

The electromagnetic Casimir effect of spherical cavity

The Casimir effect results from the zero-point energy of vacuum. A spherical cavity can be divided into three regions, and we make an analysis of every region and then give a formai solution of Casimir energy. The zeta-function regularization is also used to dispel the divergence of the summation. At the end, we can see the Casimir effect of a single sphere is included in our results.