Electron impact excitation rate coefficients of N II ion

This paper calculates the electron impact excitation rate coefficients from the ground term 2s(2)2p(2) P-3 to the excited terms of the 2s(2)2p(2), 2s2p(3), 2s(2)2p3s, 2s(2)2p3p, and 2s(2)2p3d configurations of N II. In the calculations, rnulticonfiguration Dirac-Fork wave functions have been applied to describe the target-ion states and relativistic distorted-wave calculation has been performed to generate fine-structure collision strengths. The collision strengths are then averaged over a Maxwellian distribution of electron velocities in order to generate the effective collision strengths. The calculated rate coefficients are compared with available experimental and theoretical data, and some good agreements are found for the outer shell electron excitations. But for the inner shell electron excitations there are still some differences between the present calculations and available experiments.

Influence of core property on multi-electron process in slow collisions of isocharged sequence ions with neon

Influence of core property on multi-electron process in the collisions of q = 6-9 and 11 isocharged sequence ions with Ne is investigated in the keV/u region The cross-section ratios of double-, triple-, quadruple- and total multi-electron processes to the single electron capture process as well as the partial ratios of different reaction channels to the relevant multi-electron process are measured by using position-sensitive and time-of-flight techniques The experimental data are compared with the theoretical predictions including the extended classical over-barrier model, the molecular Columbic barrier model and the semi-empirical scaling law Results show a core effect on multi-electron process of isocharge ions colliding with Neon, which is consistent with the results of Helium we obtained previously

Theoretical study of the 4d photoabsorption of the Cs+ ion

Calculations of the 4d absolute photoabsorption cross sections of the Xe-like Cs+ ion covering the energy region from 80 to 190 eV have been performed by using the multi-configuration Dirac-Fock method. The calculated cross sections are compared with the absolute experimental photoabsorption cross-section spectrum (Kjeldsen et al 2002 J. Phys. B: At. Mol. Opt. Phys. 35 2845) and other available theoretical results. In the 80-90 eV region, the discrete structure resulting from photoexcitation of a 4d electron into nf and np orbits are successfully identified. Above the 4d threshold, i.e. in the 90-190 eV energy region, a reasonable agreement between experiment and computations is found for the intense 4d -> epsilon f shape resonance.

Effects of Pairing Correlations on Formation of Proton Halo in C-9

Properties for the ground state of C-9 are studied in the relativistic continuum Hartree-Bogoliubov theory with the NLSH, NLLN and TM2 effective interactions. Pairing correlations are taken into account by a density-dependent delta-force with the pairing strength for protons determined by fitting either to the experimental binding energy or to the odd-even mass difference from the five-point formula. The effects of pairing correlations on the formation of proton halo in the ground state of C-9 are examined. The halo structure is shown to be formed by the partially occupied valence proton levels p(3/2) and p(1/2).

Experimental Study on the Exotic Structure of N-12 in RIBLL

We measured the total reaction cross sections of N-12 in Si at 36.2 MeV/u. using Radioactive Ion Beam Line in Lanzhou (RIBLL) with a new method. The reaction target was installed at the intermediate focusing point T1 at RIBLL. This scheme allows us to identify particles before and after the reaction target unambiguously. The total reaction cross section (1760 +/- 78mb) of N-12 in Si is obtained. Assuming that N-12 consists of a core C-11 plus one halo proton, the excitation function of N-12 on the Si and C targets is calculated with the Glauber model and the Fermi-Fermi density distributions. It can fit the experimental data very well. A large diffusion of the protons density distribution supports the halo structure for N-12.

Dissociative recombination of the acetaldehyde cation, CH3CHO+

The dissociative recombination of the acetaldehyde cation, CH3CHO+, has been investigated at the heavy ion storage ring CRYRING at the Manne Siegbahn Laboratory in Stockholm, Sweden. The dependence of the absolute cross section of the reaction on the relative kinetic energy has been determined and a thermal rate coefficient of k(T) = (1.5 +/- 0.2) x 10(-6) (T/300)(-0.70 +/- 0.02) cm(3) s(-1) has been deduced, which is valid for electron temperatures between similar to 10 and 1000 K. The branching fractions of the reaction were studied at similar to 0 eV relative kinetic energy and we found that breaking one of the bonds between two of the heavy atoms occurs in 72 +/- 2% of the reactions. In the remaining events the three heavy atoms stay in the same product fragment. While the branching fractions are fairly similar to the results from an earlier investigation into the dissociative recombination of the fully deuterated acetaldehyde cation, CD3CDO+, the thermal rate coefficient is somewhat larger for CH3CHO+. Astrochemical implications of the results are discussed.

PROJECTILE FRAGMENTATION OF Ar-36,Ar-40 INDUCED REACTIONS

Fragment yields for Z >= 5 from projectile fragmentation using primary beams of Ar-36,Ar-40 at 50 MeV/nucleon on Ni-64 target have been measured in RIBLL fragment separator. We compare the fragment cross sections with the predictions of the empirical EPAX parametrization of fragmentation cross-sections and Statistical Abration-Ablation model (SAA) by considering the RIBLL separator transmission rate. Isotope yield ratios between these two reactions were calculated and isoscaling parameters alpha and beta are extracted, their dependences on fragment atomic number Z and neutron number N were presented.

DISSOCIATIVE RECOMBINATION OF PROTONATED PROPIONITRILE, CH3CH2CNH+: IMPLICATIONS FOR TITAN'S UPPER ATMOSPHERE

The dissociative recombination of protonated propionitrile, CH3CH2CNH+, has been investigated at the heavy ion storage ring, CRYRING, at the Manne Siegbahn Laboratory, Stockholm University, Sweden. The thermal rate coefficient has been deduced to follow k(T) = (1.5 +/- 0.2) x 10(-6) (T/300)(-0.76) (+/-) (0.02) cm(3) s(-1) for electron temperatures ranging from similar to 10 to similar to 1000 K. Measurements of the branching fractions were performed at similar to 0 eV relative kinetic energy. It has been found that in 43% +/- 2% of the reactions the four heavy atoms remain in the same product fragment. An equal portion of the reactions leads to products where one of the heavy atoms is split off from the other three and 14% +/- 1% result in a breakup into two heavy fragments containing two heavy atoms each. We discuss the significance of the data to Titan's upper atmosphere.

Experimental studies of the dissociative recombination of CD3CDOD+ and CH3CH2OH2+

Aims. We determine branching fractions, cross sections and thermal rate constants for the dissociative recombination of CD3CDOD+ and CH3CH2OH2+ at the low relative kinetic energies encountered in the interstellar medium. Methods. The experiments were carried out by merging an ion and electron beam at the heavy ion storage ring CRYRING, Stockholm, Sweden. Results. Break-up of the CCO structure into three heavy fragments is not found for either of the ions. Instead the CCO structure is retained in 23 +/- 3% of the DR reactions of CD3CDOD+ and 7 +/- 3% in the DR of CH3CH2OH2+, whereas rupture into two heavy fragments occurs in 77 +/- 3% and 93 +/- 3% of the DR events of the respective ions. The measured cross sections were fitted between 1-200 meV yielding the following thermal rate constants and cross-section dependencies on the relative kinetic energy: sigma(E-cm[eV]) = 1.7 +/- 0.3 x 10(-15)(Ecm[eV])(-1.23 +/- 0.02) cm(2) and k(T) = 1.9 +/- 0.4 x 10(-6)(T/300)-0.73 +/- 0.02 cm(3) s(-1) for CH3CH2OH2+ as well as k(T) = 1.1 +/- 0.4 x 10(-6)(T/300)(-0.74 +/- 0.05) cm(3) s(-1) and s(Ecm[eV]) = 9.2 +/- 4 x 10(-16)(Ecm[eV])-1.24 +/- 0.05 cm(2) for CD3CDOD+

中低能重离子碰撞中x-射线产生截面的理论研究

本工作应用Visual Fortran编写了ECPSSR理论计算程序，修正了ISICS程序中的错误，本程序可以对各种入射离子与靶原子的组合进行计算，给出K，L，M的壳层及次壳层电离截面以及相应的x-射线产生截面，并根据需要选择是否对入射离子运动进行相对论修正。采用所编写的程序计算了一些碰撞体系的电离截面和x-射线产生截面，并与其他程序的计算结果和实验数据分别进行了比较。对于低能离子入射， ECPSSR计算的x-射线产生截面值明显低于实验值。考虑到低能入射离子可能会与靶原子形成准分子，本工作采用联合分离原子(USA, united and separated atom)模型替代ECPSSR中的PSS模型，考虑分子轨道(M)效应得到了基于联合分离原子模型的电离模型－MECUSAR。编写了相应的程序并对部分碰撞系统进行了计算，将计算得到的碰撞截面与实验进行比较，发现对于较低能量重离子碰撞，MECUSAR计算值好于ECPSSR计算值，对于轻离子入射，MECUSAR计算值与ECPSSR值基本相符，而计算K壳层x-射线产生截面时，ECPSSR计算值好于MECUSAR计算值

Ar16+ 离子与Au和Mo靶相互作用产生的X射线截面随入射角度的变化

本实验工作是在兰州重离子加速器国家实验室ECR离子源完成。实验采用能量为336keV的低能高电荷态Ar16+离子轰击Au、Mo金属靶，入射离子与靶表面之间的夹角分别是20°，25°，……，80°，入射角与出射角之和为90°。测量了不同角度下Mo的Lα、Lβ，Au的Mα和Ar的Kα特征X射线谱，对实验谱进行了高斯拟合，计算了不同入射角下的各条X射线的产额和产生截面，并将靶原子发射出的X射线截面与ECPSSR和带结合能修正的BEA理论计算的结果进行了比较。发现当入射角较小时，Ar16+与金属靶相互作用时所产生出的各条特征X射线截面随入射角的增加而增加，当入射角达到40°左右后X射线截面基本上保持不变。与ECPSSR计算值相比，本实验中Au的X射线截面比较接近，实验值比ECPSSR计算值小不到一个量级；而Mo的X射线截面实验值比ECPSSR计算值大3-4个量级，但产额与带结合能修正的BEA计算值很接近

Au LX射线发射截面和Al、Ti、Ni表面可见、红外光谱测量

本实验工作是在中国原子能科学研究院的HI-13串列加速器国家实验室第二测量厅原子物理实验平台上完成。本工作采用能量为20-50MeV的高电荷态O5+离子去轰击Au, 测量了不同能量下Au的L1、Lα、Lβ、Lγ的X射线谱，计算了不同能量下各条X射线的产生截面，并与ECPSSR理论计算结果进行了比较。实验结果表明σ（Ll）/σ(Lα) 和σ（Lγ）/σ(Lα)与ECPSSR理论计算结果符合比较好，而对于σ（Lβ）/σ(Lα)，在较低能区实验值略高于理论值。在中国科学院近代物理研究所320kV高电荷态离子实验研究平台上测量了Xeq+ (q=17-29)入射Al、Ti和Ni等表面诱发的可见光和红外光。通过对靶原子光谱线的研究，实验发现，随着入射离子的电荷态增高，原子和离子的各种光谱线可得到有效地激发。低速高电荷态离子入射金属固体表面，靶原子的特征谱线的激发强度，与入射离子的电荷态q密切相关。qc的实验测量值和理论计算值符合的较好

12N、12B、11C 在Si靶上反应总截面研究

核反应总截面是描述原子核反应基本特征的一个重要的物理量，从中可以得到有关核反应、核结构和核内核子分布的信息。在由放射性束所产生的奇异核结构与各种反应机制的研究中，反应总截面更是具有特殊的重要性。具有奇异核结构的核的一个典型物理现象就是其反应总截面要比稳定核大得多，I.Tanihata等人最早就是通过对放射性束流的相互作用截面的测量发现了具有奇异结构的核－中子晕核。由于反应截面的测量对探测器的要求不高，而且数据分析过程相对较为简单，因此反应截面的测量已经成为放射性束物理研究的一个非常重要的实验手段。目前，奇异核研究的重点在丰中子一侧，理论预言的很多中子晕核如8He、11Li、11、14Be、15、17、19C、等已经从实验上得到证实，而理论预言的质子晕核目前只有8B得到实验证实，其他的核实验数据较少或相互矛盾，无法作出准确的结论。12N就是其中之一，理论学家认为其具有质子晕结构；而实验数据主要集中在的反应截面测量上，实验数据较少又相互矛盾或不肯定，不能得出确切结论。因此，进一步开展研究是十分必要和有意义的。考虑到以上因素，充分利用兰州放射性束流线现有的实验条件，我们采用束流透射法测量了中能区多个能量点12N、11C、12B与Si靶的反应总截面和12N去质子截面。同时用CLOVER探测器测量与碎片符合的γ能谱。利用透射法测量核的反应总截面对于模型没有依赖性，因而得到的结果更加可靠。利用Shen公式和采用各种密度分布形式的零力程Glauber模型计算了12N、11C、12B的激发函数并与实验结果比较，提取了12N、11C、12B的密度分布与核半径，对12N去质子截面作了简单分析。使用Shen公式拟合实验数据时发现，Shen公式在整个能区范围内基本上可以很好的拟合12B、11C的反应数据，但Shen计算得到的12N的反应总截面与实验测量值有明显的差异，计算结果偏小。在使用Glauber模型拟合实验数据之前，分别使用有限力程和零力程Glauber模型拟合了12C＋12C的实验数据。在计算时，两种Glauber模型输入的密度分布采用Gauss密度分布形式。结果显示，使用零力程Glauber模型可以更好的拟合实验数据。分别使用高斯密度分布、HO密度分布、双参数费米密度分布、SHF模型计算得到的密度分布、基于少体模型的Gauss＋尾巴密度分布形式代入零力程Glauber模型拟合实验数据。对于12B、11C、12C，这些密度分布形式代入零力程Glauber模型计算得到的激发函数曲线在整个能区范围内都可以很好的拟合实验数据。但是对于12N，只有基于少体模型的Gauss＋尾巴密度分布形式代入零力程Glauber模型计算得到的激发函数曲线可以拟合实验结果。其他的密度分布形式计算得到的激发函数曲线明显低于实验数据。提取的12B、11C、12N均方根半径显示，12N的核半径明显大于其镜像核12B及其周围的核素。对12B、11C、12N的分析结果表明：12N的密度分布形式和稳定核有明显的不同，最后一个质子的密度分布具有很大的弥散，其可能具有奇异结构。对12N去质子截面的简单分析也表明了这一点

放射性核素引起反应中同位素分布的同位旋效应及19Na产生截面的ya研究

本论文介绍了放射性核束物理研究的现状以及当前常用的几种同位旋相关的重离子微观输运理论，对传统的 Boltzmann-Langevin 方程（BLE）考虑了同位旋相关的平均场、核子-核子碰撞截面和泡里阻塞，面且在初始化相空间的抽样中区分了中子和质子，并合模型也考虑了同位旋效应，建立了同位旋相关的 Boltzmann-Langevin 方程（IBLE）。利用IBLE对放射性核引起反应中的同位素分布，~(19)Na 的产生截面，以及中能重离子碰撞中的径向膨胀流进行了系统的研究，并对超重核的合成进行了一些初步的讨论。利用 IBLE 分别研究了不同弹核 ~(14)O，~(16)O 和 ~(18)O 在入射能量为 28.7MeV/u 下轰击不同靶核~7Be 和 ~9Be的反应，计算生成碎片的产生截面，发现用丰中子（缺中子）炮弹或丰中子（缺中子）靶进行反应，所得到的产物均有丰中子（缺中子）的碎片出现。同位素分布宽度和峰位入射体系密切相关，产生碎片的电荷数越接近于入射弹核的电荷数，则同位素分布的宽度越大，峰位偏离β稳定线值越远，其同位旋效应越明显。在28.7 MeV/u入射能量下，对反应系统 ~(17-20,22)Ne + ~(12)C 和 ~(20)Ne + ~9 进行了研究。对核素 ~(19)Na 产生截面进行计算和比较后，发现缺中子核引起的反应，具有更大~(19)Na的产生截面。通过研究反应系统 ~(40)Ca + ~(58)Ni 和 ~(40)Ca + ~(58)Fe 的径向膨胀流随入射能量的变化关系，发现径向膨胀流存在着强烈的同位旋相关性。利用径向膨胀流随入射能量的变化关系和拟和结果，从理论上证实了存在使径向膨胀流为零的特定入射能量，发现对于不同的反应体系这个能量是不同的，它随同位旋自由度的变化而变化。

20Ne轰击Be靶碎裂产物核反应总截面的测量

核反应总截面是表征原子核反应基本特征的一个基本量，从实验测得的核反应总截面中可以得到有关核反应、核结构和核内核子分布的信息。在由放射性束流所产生奇异核的结构与各种反应机制研究中，反应总截面的测量更是具有特殊的重要性，具有奇异晕核结构的核的一个典型的物理现象就是其反应总截面要比稳定核大很多，I．Tanihata等人最早就是通过对放射性束流的相互作用截面的测量发现了具有奇异结构的核，即中子晕核。这次实验结果得出的跟放射性奇异核性质等有关的一些有趣现象，为放射性束核物理的研究注入了新的活力。我们采用能量为80MeV／u的初级束~(20)Ne轰击3 mm厚的Be靶，在RIBLL上测量了由初级靶上产生碎裂反应所得到的次级~(12)N，~(17)F和~(17)Ne等质子滴线核在Si靶上的中能核反应总截面σ_R，从而补充了现有的中能区放射性核反应总截面的实验数据。由于~(12)N，~(17)F和~(17)Ne都是理论预言可能具有奇异质子结构(质子晕或质子皮)的核，测量它们在中能区的核反应总截面，可以对上述预言提供实验上的检验。在与相邻同位素核的反应截面测量结果的比较中，发现，~(12)N，~(17)F反应截面值明显偏大，~(17)Ne的截面值没有异常。利用基于库仑修正和有限程修正后的微观Glauber模型拟合实验数据，我们发现：对于~(12)N，理论计算反应截面曲线同实验数据明显偏离，因此，它可能具有奇异结构；对于~(17)F，曲线与实验数据符合，没有给出奇异结构特征；对于~(17)Ne，实验和理论分析都没有发现奇异结构。对核反应总截面进行研究的一个有用的理论就是G1auber模型，该模型是一种基于自由核子－核子(N－N)碰撞的与核物质密度有关的理论，因而能够从实验测量到的反应总截面中提取核物质分布的信息。但现有的理论模型不能正确描述中能下核反应总截面。为了改变这一现象，我们对其进行了有限程的修正，并引入一种能够正确描述核物质密度分布的双参数的费米分布，使得实验结果与理论计算在中、高能下都符合的很好。对于奇异核的描述，我们采用核芯加奇异核子的方法，并带入Glauber模型中进行计算，结果与实验值完全重合。这也说明了我们采用的形式正确描述了奇异核的存在方式。