THE STUDIES OF NON-RUTHERFORD BACKSCATTERING CROSS SECTIONS OF 4He FROM 16O

In this article, we report the 170° backscattering cross sections of ⁴He from ¹⁶O in the energy range of 2.0-9.0 MeV. Our measurements show that the alpha-oxygen scattering remains Rutherford scattering up to E_α=2.35 MeV, and there exist two energy regions, namely 5.55-5.85MeV and 8.50-8.80MeV, where the cross sections are enhanced and show a smooth variation. The measured laboratory cross sections are 9.50-9.97 and 35.0-33.0 times greater than the Rutherford values, respectively. In the 8.50-8.80MeV region, the cross sections at scattering angles of 160°, 165°, 170° and 175° were measured and found to be strongly angle-dependent. A most strong resonance occurred at 7.60 MeV, where the cross section is 200 times of its Rutherford value. This resonance has been used to measure the ¹⁶O concentration on a Cu surface, with a sensitivity of 1×10¹⁵ oxygen atoms/cm², Besides, we have studied the backscattering angle dependence of the threshold energy, i.e., the energy at which the elastic cross section begins to deviate from its Rutherford value. The experimental result seems not in agreement with the prediction made from the analytical formula developed by Bozoian et al.     

Elastic Scattering of 6He + p at 82.3MeV/nucleon

Differential cross sections for the elastic scattering of halo nucleus 6He on proton target were measured at 82.3 MeV/u. The experimental results axe well reproduced by optical model calculations using global potential KD02 with a reduction of the depth of real volume part by a factor of 0.7. A systematic analysis shows that this behavior might be related to the weakly bound property of unstable nuclei.     

THE STUDIES OF NON-RUTHERFORD BACKSCATTERING CROSS SECTIONS OF 4He FROM 16O

In this article, we report the 170° backscattering cross sections of ⁴He from ¹⁶O in the energy range of 2.0-9.0 MeV. Our measurements show that the alpha-oxygen scattering remains Rutherford scattering up to E_α=2.35 MeV, and there exist two energy regions, namely 5.55-5.85MeV and 8.50-8.80MeV, where the cross sections are enhanced and show a smooth variation. The measured laboratory cross sections are 9.50-9.97 and 35.0-33.0 times greater than the Rutherford values, respectively. In the 8.50-8.80MeV region, the cross sections at scattering angles of 160°, 165°, 170° and 175° were measured and found to be strongly angle-dependent. A most strong resonance occurred at 7.60 MeV, where the cross section is 200 times of its Rutherford value. This resonance has been used to measure the ¹⁶O concentration on a Cu surface, with a sensitivity of 1×10¹⁵ oxygen atoms/cm², Besides, we have studied the backscattering angle dependence of the threshold energy, i.e., the energy at which the elastic cross section begins to deviate from its Rutherford value. The experimental result seems not in agreement with the prediction made from the analytical formula developed by Bozoian et al.     

Angular Dispersion and Deflection Function for Heavy Ion Elastic Scattering

The differential cross sections for elastic scattering products of ^17F on ^208Pb have been measured. The angular dispersion plots of ln（dσ/dθ） versus θ^2 are obtained from the angular distribution of the elastic scattering differential cross sections. Systematical analysis on the angular dispersion for the available experimental data indicates that there is an angular dispersion turning angle at forward angular range within the grazing angle. This turning angle can be clarified as nucleal rainbow in classical deflection function. The exotic behaviour of the nuclear rainbow angle offers a new probe to investigate the halo and skin phenomena.     

Electron Scattering by C4H10 and C6H6 in the Energy Range 100--1000eV

We investigate the applicability of the independent atom model （IAM） to elastic electron scattering from complex polyatomic molecules, namely C4H10 and C6H6, in the energy range 100-1000eV. The cross sections of the elastic electron scattering are calculated by employing the IAM together with the relativistic partial waves. The incorporation of both the modified absorption potential and the extended structural factor in the IAM makes the elastic differential cross sections and momentum transfer cross sections have a good agreement with the available experimental data. The present simple model seems to be insensitive to the complexity of the target molecules so that the proposed procedure can be quite useful for calculation of electron scattering from bio-molecules.     

Notch Test for Radial Sensitivity on Neutron Density Distribution in ^48Ca Probed by α-Particle Elastic Scattering

Notch tests are made to study the sensitive regions in the neutron density distribution in the ground state of^48 Ca probed by the angular distributions of differential cross sections of α-particle elastic scattering at 104 MeV with optical model potentials calculated by using a systematic single-folding model. An improved notch scheme is proposed, which perturbs the neutron density distribution of the target nucleus locally. Results of the notch tests show that the angular distribution of differential cross sections for α particle elastic scattering at 104 MeV only probe the surface of the neutron density distribution in ^48Ca.     

New measurements and phase shift analysis of p~(16)O elastic scattering at astrophysical energies

The results of new experimental measurements of p~(16)O elastic scattering in the energy range of 0.6–1.0MeV at angles of 40°–160° are given. Phase shift analysis of p~(16)O elastic scattering was made using these and other experimental data on differential cross sections in excitation functions and angular distributions at energies of up to 2.5 Me V.     

Simulation and analysis of 13N+p elastic resonance scattering

The ^13 N＋p elastic resonance scattering has been studied at the secondary radioactive beam facility of CIAE in inverse kinematics via a thick-target method. The excitation function for the ^13N（p,p） scattering was obtained in the energy interval of Ecru ≈0.5-3.2 MeV with a ^13 N secondary beam of （47.8±1.5） MeV. Careful analysis of the secondary beam components and extensive Monte-Carlo simulations enable the resolution of the experimental proton spectra. The resonance parameters for five low-lying levels in ^14 O were deduced by Rmatrix fitting calculations with MULTI7 and SAMMY-M6-BETA. The present results show general agreement with those from a recent similar work, and thus confirm the observation of a new 0^- level at 5.7 MeV in 140 with an improved width of 400（45） keV.     

CDCC Approaches and Roles of Closed Channels in d-Nucleus Reactions

The effect of deuteron breakup in d-nucleus reaction is treated with the continuum discretized coupled channels （CDCC） approach, and the effects on the total reaction cross sections and elastic scattering angular distributions are studied by comparing the calculations of CDCC and spherical optical model with our global deuteron optical potential [Phys. Rev. C 73 （2006） 054605] below 200 MeV, for target nuclei ranging from ^12C to ^208Pb. The contributions from the closed channels to the total reaction and breakup cross sections, and angular distributions of elastic scattering are also seriously discussed.     

MENDF—一个计算200 MeV以下裂变核数据的程序(英文)

基于球型光学模型、 预平衡发射和Hauser-Feshbach统计等理论, 编制了MENDF（Medium Energy Nuclear Data for Fission）程序, 该程序适用于裂变核在入射粒子能量低于200 MeV的中低能区的全套核数据计算。 对于中子和质子在200 MeV以下诱发的核反应, 其全截面、 反应截面、 弹性散射微分截面、 裂变截面和裂变中子谱、 5种发射粒子的单举截面和相应的能谱等理论计算值与相应的实验值基本符合。 MENDF在我国已被广泛用于核数据计算及建立中能核数据库。Based on the spherical optical model, pre equilibrium and Hauser Feshbach statistical theory, the code MENDF (Medium Energy Nuclear Data for Fission) is written to calculate a complete set of nuclear data for fission nuclei in the medium low energy region (≤200 MeV). For neutron and proton induced reactions below 200 MeV, the total cross sections, reaction cross sections, elastic scattering differential cross sections, fission cross section, energy spectra of fission neutron and five kinds of emitting particles, etc. are calculated by MENDF. The calculated data generally agree with their corresponding experimental data. MENDF is widely used for nuclear data calculation and to establish ENDF 6 formatted files for the medium low energy region in China.     

erent Phase Control in e-Ar Scattering in a Bichromatic Laser Field in the Second Born Approximation

We study the elastic scattering of atomic argon by an electron in the presence of a bichromatic laser field in the second Born approximation. The target atom is approximated by a simple screening potential. We explore the dependences of the differential cross sections on the relative phase φ between the two components of the radiation field and discuss the influence of the number of photons exchanged on the phase-dependence effect. Moreover, for different scattering angles and incident electron energies, the differential cross sections are notably different.     

Exotic Behaviour of Angular Dispersion of Weakly Bound Nucleus ^17F at Small Angles

The differential cross sections of ^17F and ^17O elastic scattering products on ^208Pb have been measured at the Radioactive Ion Beam Line at Lanzhou （RIBLL）. Two angular dispersion plots of In（ dσ/ dθ ） versus 02 are obtained from the angular distribution of the elastic scattering differential cross sections. The angular dispersion plot exhibits a clear turning point for ^17F in the range of small scattering angles 6°-2° due to its exotic structure, but for ^17O, the turning point is not observed in the same angular range. The experimental results have been compared with previous data of other groups. Systematical analysis on the available data supports the above conclusion that there is an exotic behaviour of the angular dispersion plot of weakly bound nuclei with halo or skin structure as compared with that of the ordinary nuclei near stable line. Therefore the turning point of the angular dispersion plot appears at small angle for weakly bound nuclei with halo or skin structure, and can be used as a new probe to investigate the halo and skin phenomena of weakly bound nuclei.     

Excited States in ^18Ne Studied via ^17F＋p

The elastic resonance scattering of ^17F＋p is studied in inverse kinematics via a thick-target method. The excitation function for ^17F＋p elastic scattering is obtained within the energy interval of Ec.m ≈ 0.4-1.7 MeV. The experimental excitation function is analyzed with a multilevel R-matrix code MULTI7, and the proton widths are deduced. The α decay from 6.15 MeV 1- state in 18Ne is observed, which is critical to the 14O（α, p）17F reaction as the main breakout route from CNO cycle to rp-process in supernovae and x-ray bursts.     

4.2 GeV α-^12C Elastic Scattering Based on α-Particle Model

Based on the α-particle model of ^12C nucleus, the differential cross sections for α-^12C elastic scattering at incident energy of 4.2 GeV have been calculated within the framework of Glauber multiple scattering theory. The results show that the main features of the measured angular distribution of the cross sections can be reasonably described. The parameterized α-α scattering amplitude, which is the basic input to construct the α-^12 C scattering Glauber amplitude in the a-particle model, is obtained by fitting the α-α scattering data.     

Differential, elastic integral and moment transfer cross sections for electron scattering from N2 at intermediate- and high-energies

A complex optical model potential modified by incorporating the concept of bonded atom, with the overlapping effect of electron clouds between two atoms in a molecule taken into consideration, is firstly employed to calculate the differential cross sections, elastic integral cross sections, and moment transfer cross sections for electron scattering from molecular nitrogen over the energy range 300—1000eV by using additivity rule model at Hartree—Fock level. The bonded-atom concept is used in the study of the complex optical model potential composed of static, exchange, correlation polarization and absorption contributions. The calculated quantitative molecular differential cross sections, elastic integral cross sections, and moment transfer cross sections are compared with the experimental and theoretical ones wherever available, and they are found to be in good agreement with each other. It is shown that the additivity rule model together with the complex optical model potential modified by incorporating the concept of bonded atom is completely suitable for the calculations of differential cross section, elastic integral cross section and moment transfer cross section over the intermediate- and high-energy ranges.     

Positron total cross sections for collisions with N2 and CO2 at 30-3000 eV

The total (elastic plus inelastic) cross sections for positron scattering from N2 and CO2 over the incident energy range from 30 to 3000eV are calculated using the additivity rule model at Hartree-Fock level.A complex optical model potential modified by incorporating the concept of bonded atom, which takes into account the overlapping effect of electron clouds between two atoms in a molecule, is employed to calculate the total cross section of positron-molecule scattering. The calculated total cross sections are in good agreement with those reported by experiments and other theories over a wide energy range.     

Positron total cross sections for collisions with N_2 and CO_2 at 30-3000 eV

The total (elastic plus inelastic) cross sections for positron scattering from N2 and CO2 over the incident energy range from 30 to 3000eV are calculated using the additivity rule model at Hartree-Fock level. A complex optical model potential modified by incorporating the concept of bonded atom, which takes into account the overlapping effect of electron clouds between two atoms in a molecule, is employed to calculate the total cross section of positron-molecule scattering. The calculated total cross sections are in good agreement with those reported by experiments and other theories over a wide energy range.     

Tritium and helium analyses in thin films by enhanced proton backscattering

In order to study how to reliably perform quantitative tritium and helium analyses in thin film samples using enhanced proton backscattering(EPBS),several EPBS spectra for some samples consisting of non-RBS light elements(i.e.,T,4He,12C,16O,natSi),medium and heavy elements have been measured and analyzed using analytical SIMNRA and Monte Carlo-based CORTEO codes.The non-RBS cross sections needed in the CORTEO code are taken from the ENDF/B-Ⅶ.1 database and the calculations of SigmaCalc code and are incorporated into the CORTEO code.All non-RBS cross section data over the entire proton incident energy-scattering angle plane are obtained by interpolation.It is quantitatively observed that in EPBS analysis the multiple and plural scattering effects have little impact on the energy spectra for light elements and the RBS cross sections of light elements can be used in the SIMNRA code for dual scattering calculations.It is also observed that the results given by the CORTEO code are higher than the results of the SIMNRA code in the low energy part of EPBS spectra,and are in better agreement with the experimental data.Tritium and helium analyses in thin film samples using EPBS can be performed reliably when the multiple and plural scattering contributions are completely accounted.     

MEND——-—个计算250 MeV以下中重核数据的程序(英文)

基于球型光学模型、 预平衡发射和Hauser Feshbach统计等理论, 编制了MEND程序（Medium Energy Nuclear Data）, 该程序适用于中重原子核在入射粒子能量低于250 MeV的中低能区的全套核数据计算。对于中子和质子在250 MeV以下诱发的核反应, 其全截面、 反应截面、 弹性散射微分截面、 双微分截面和能谱等理论计算值与相应的实验值基本一致。MEND是计算中低能核反应的基础程序, 在我国已被广泛用于核数据计算及建立中能核数据库Based on the spherical optical model, pre equilibrium statistical theory, and Hauser Feshbach theory, etc., the code MEND (Medium Energy Nuclear Data) is written for calculating the complete set of nuclear data of medium heavy nuclei in medium low energy region (≤250 MeV). For the reactions induced by neutron and proton below 250 MeV, the total cross sections, reaction cross sections, elastic scattering differential cross sections, double differential cross sections and energy spectra, etc. calculated by the code MEND, generally agree with those corresponding experimental data. MEND is a foundational program for nuclear reaction in medium low energy region and is wildely used for nuclear data calculation and establishing ENDF/B6 format files of medium low energy region in China.     

Nuclear Halo-Like Phenomena of 6,8He and Nuclear Short Range Correlation

Based on the nuclear short range correlation in a halo-like nucleus, theoretical analysis of the experimental cross sections for small-angle elastic p-^4,6,8 He scattering at the energy of about 0.7 GeV has been performed in the framework of Glauber multiple scattering theory. Our theoretical calculations reproduce the corresponding experimental data quite successfully. These good agreements confirm that the nuclear halo-like phenomena may originate from the short range correlation between nucleons in a halo-like nucleus.