6Li与核弹性散射的微观光学势

从基本的Dirac-Brueckner-Hartree-Fock微观理论出发,得到同时包含实部和虚部的核子-核散射的微观光学势,并利用折叠模型直接获得了核-核散射参数无关的整体微观光学势.考虑到核-核散射去弹过程高级项的贡献和⁶Li的碎裂效应,在微观光学势的实部和虚部中引入了修正因子N_R,N_I.系统研究了入射粒子⁶Li与靶核¹²C,²⁸Si,关键词： 弹性散射 Dirac-Brueckner-Hartree-Fock方法 折叠模型 微观光学势     

双折叠模型对相互作用势实部的计算

用双折叠模型计算了核核碰撞的相互作用势, 其中核子-核子相互作用势采用M3Y-Reid和M3Y-Paris形式, 交换部分考虑了有限力程的密度依赖的核子-核子相互作用, 程序用于重离子散射光学势实部的计算. 回顾了折叠模型的普遍特征和讨论了理论计算过程, 对各种类型的核子-核子相互作用下计算的相互作用势进行比较, 发现双折叠模型对大部分系统相互作用势的实部取得了满意的结果. 因此这个工作为重离子相互作用势的折叠计算提供了很好的方法.     

质子滴线核12N在28Si靶上的核反应总截面测量

描述了50.4MeV/u的¹²N和42.3MeV/u的¹³N次级放射性束在²⁸Si靶上引起的核反应总截面σ_r实验研究,结果发现¹²N的反应总截面σ_r比其相邻同位素核¹³N有着异常的增大.这可能是核形变及核子对效应造成的,试验中的测量误差也不可忽视.利用微观Glauber模型计算了¹²N在²⁸Si靶上的核反应总截面,并与实验结果做了比较,发现理论计算与实验结果拟合较好 关键词： 质子晕 反应截面     

中性硅3s23P2 3P2,1D2→3s3p3 3D3o跃迁能量,超精细结构常数与同位素移动的MCDHF计算

本文使用多组态Dirac-Hartree-Fock方法计算了²⁹Si的3s²3p^{2 3}P₂,¹D₂→3s3p³D₃⁰跃迁能量和³P₂,³D₃⁰超精细结构A常数以及Si同位素²⁹Si,³⁰Si和³¹Si相对于²⁸Si在3s²3p^{2 3}P₂→3s3p^{3 3}D₃⁰跃迁的同位素移动.通过尝试双电子激发（SD）和三电子激发（SDT）,分别考虑VV相关,CV相关和CC相关产生各种不同的扩展组态波函数得到的计算结果和实验值的比较,推测了对于中性硅原子这两个组态,内壳层2p2s,1s电子活动到外壳层的概率较小,而3s3p壳层中的电子都比较活跃,但主要是在n=3,4的壳层内活动,活动到更高n壳层的概率则比较小.     

激发态丰质子核的双质子发射

将有效液滴模型和推广的液滴模型推广至激发态丰质子核的双质子发射半衰期研究,发现这两个模型都能较好地再现双质子发射半衰期的实验数据.基于这两个模型预言了一些核的激发态的双质子发射的半衰期,为将来的实验提供参考,并将上述半衰期与统一裂变模型给出的半衰期进行了比较和分析.此外,以⁹⁴Ag的21~+激发态的双质子发射为例,讨论了衰变能和衰变过程中带走的轨道角动量对其半衰期的影响,发现半衰期对它们的依赖很敏感,半衰期对衰变能的强烈依赖表明了精确测量核质量和激发能的重要性和必要性.     

原子核壳模型单体密度矩阵的数值计算

提出平均场壳模型下原子核单体密度矩阵的一种计算方法,验证该方法的可靠性.计算双幻核⁴⁰Ca,⁹⁰Zr的单体密度矩阵,利用单体密度矩阵计算核子密度分布和动量分布,并分别与Hartree-Fock-Bogolubov理论结果、定域费米气体模型结果以及实验数据进行比较.     

核磁共振研究大叶蛇葡萄提取物蛇葡萄素

通过质子检测的¹³C-¹H异核多键化学位移相关谱、¹³C-¹H异核多量子化学位移相关谱和质子相敏交换谱等NMR二维方法确定了传统中草药大叶蛇葡萄提取物的结构为蛇葡萄素(3,3',4',5,5',7-六羟基双氢黄酮醇),得到了更加准确的¹H和¹³C化学位移归属,并观测和讨论了这一体系中溶剂二甲亚砜的质子化现象.     

同位旋效应对中能重离子反应中轻粒子产物的影响

利用同位旋相关的量子分子动力学模型,研究了¹¹²Sn+¹¹²Sn和¹²⁴Sn+¹²⁴Sn两反应系统在不同入射能量、不同碰撞参数、不同势场和不同核子-核子碰撞截面下的粒子发射特征.阐述了发射体系的同位旋对轻粒子产额比的影响.发现轻粒子产额比是同位旋的敏感观测量.另外,还发现中快度区发射的粒子有更高的丰中子程度.同时,轻粒子的比不敏感于核子核子碰撞截面,而敏感于核态方程,这使得从轻粒子比提取同位旋相关的核态方程变成一种可能. 关键词： 同位旋相关的量子分子动力学 同位旋效应 轻粒子产额比     

1-[2-(2,4-二氯苯基)-4-烷基-1,3-二氧戊环-2-基甲基]-1H-1,2,4-三唑的NMR研究

测定了戊环唑（1）、甲环唑（2）、丙环唑（3）的NMR谱,对其一般特征进行 了对比与讨论,用¹³C-¹H COSY、¹³C-¹H COLOC、DQF-COSY、DEPT等技术对它们的¹H、¹³C NMR谱峰进行了全归属,并应用¹H-¹H NOESY谱研究其立体结构.
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基于色散光学模型的40Ca核子散射数据计算

对钙同位素核数据的研究具有重要的理论价值和应用前景,其中⁴⁰Ca作为天然钙最主要的同位素,是一种重要的材料核素.本文采用色散光学模型对球形核⁴⁰Ca的核子弹性散射数据进行计算.通过考虑色散光学模型势中实部势的非定域性以及虚部势的壳间隙结构,实现了对⁴⁰Ca相关核子散射数据的良好描述,其中包括中子总截面、核子弹性散射角分布以及分析本领.此外,本文计算了色散光学模型势的实部体积分,其随能量的变化图像在费米能附近出现了明显的色散峰结构.     

Clusters decay half-live of various heavy deformed nuclei with mass numbers in the range 221 ≤ A ≤ 242

Decay half-live of several clusters between ¹⁴C and ³⁴Si emitted from various heavy deformed nuclei with mass numbers in the range 221 ≤ A ≤ 242 are calculated using nuclear Woods-Saxon (V_N(r, θ)), Coulomb (V_C(r, θ)) and rotational (V_l(r)) potentials considering deformation for both daughter and cluster and spherical configuration for them. Half-live of these decays are also obtained using a semi-empirical formula. Obtained results considering deformation are compared with the half-live of spherical configuration, results of a semi-empirical formula as well as the available experimental data. The comparison indicates that the calculated half-lives considering deformation are better agreed with the experimental data than the results of spherical configuration and the out put of semi-empirical formula. Also, The obtained results using deformation is better confirmed the Geiger-Nuttall low of alpha decay, especially for emission of light clusters as expected.     

Alpha-clustering effects in heavy nuclei

The study of cluster structures in light nuclei is extending to the heavy nuclei in these years. As for the stable N = Z nuclei, from the lighter ⁸Be, ¹²C nuclei to the heavier ²⁰Ne and even the ⁴⁰Ca and ⁴⁴Ti medium nuclei, the α cluster structures have been well studied and confirmed. In heavy nuclei, due to the dominated mean field, the existence of α cluster structure is not clear as light nuclei but some clues were found for indicating the core+α cluster structure in some nuclei, in particular, the ²⁰⁸Pb+α structure in ²¹²Po. We review some recent progress about the theoretical and experimental explorations of the α-clustering effects in heavy nuclei. We also discuss the possible α cluster structure of heavy nuclei from the view of α decay.     

Gamma radiation following heavy ion reactions

The gamma radiation produced by bombarding ²⁷A1 and ²⁸Si targets with 25–50 MeV ¹⁶O ions was measured in order to study the formation and decay of the highly excited compound nuclei ⁴³Sc and ⁴⁴Ti. The relative population of the evaporation residues is fairly well reproduced by a statistical theory describing the successive emission of 1–3 light fragments. From the measured branching ratio between proton and α-particle emission, the moment of inertia parameter of the level density is found to be close to the rigid body value. The influence of heavy ion optical transmission factors, level density parameters and γ-ray decay widths of continuum states is investigated.     

A statistical approach to describe highly excited heavy and superheavy nuclei

A statistical approach based on the Weisskopf evaporation theory has been developed to describe the deexcitation process of highly excited heavy and superheavy nuclei, in particular for the proton-rich nuclei. The excited nucleus is cooled by evaporating γ-rays, light particles(neutrons, protons, α etc) in competition with binary fission,in which the structure effects(shell correction, fission barrier, particle separation energy) contribute to the processes.The formation of residual nuclei is evaluated via sequential emission of possible particles above the separation energies.The available data of fusion-evaporation excitation functions in the ~(28)Si+~(198)Pt reaction can be reproduced nicely within the approach.     

Cold reaction valleys in the radioactive decay of superheavy 286112, 292114, and 296116 nuclei

Cold reaction valleys in the radioactive decay of superheavy nuclei ²⁸⁶112, ²⁹²114, and ²⁹⁶116 are studied taking Coulomb and Proximity Potential as the interacting barrier. It is found that in addition to alpha particle, ⁸Be, ¹⁴C, ²⁸Mg, ³⁴Si, ⁵⁰Ca, etc. are optimal cases of cluster radioactivity since they lie in the cold valleys. Two other regions of deep minima centered on ²⁰⁸Pb and ¹³²Sn are also found. Within our Coulomb and Proximity Potential Model half-life times and other characteristics such as barrier penetrability, decay constant for clusters ranging from alpha particle to ⁶⁸Ni are calculated. The computed alpha half-lives match with the values calculated using Viola-Seaborg-Sobiczewski systematics. The clusters ⁸Be and ¹⁴C are found to be most probable for emission with T _1/2 < 10³⁰ s. The alpha-decay chains of the three superheavy nuclei are also studied. The computed alpha-decay half-lives are compared with the values predicted by Generalized Liquid Drop Model and they are found to match reasonably well.     

Light and heavy ion transfer reactions among light nuclei

A comparison is made between two transfer reactions involving the same target and final nuclei, ²⁶Mg and ²⁸Si. The (τ, n) and (¹⁶O, ¹⁴C) ground band reactions are considered, representing light and heavy ion projectiles. Despite the rather complicated nuclear structure transition involved in these reactions, the spectroscopic features of the two reactions are very similar. In both cases inelastic transitions entail major contributions from multistep processes.     

A search for spontaneous emission of heavy clusters in the 127I nuclide

The results of an experimental search for spontaneous cluster decay in ¹²⁷I are presented. Several possible channels have been investigated considering an exposure of 33834 kg ^. day collected by a large-mass highly radiopure NaI(Tl) set-up deep underground in the Gran Sasso National Laboratory of the INFN. New lower limits on the lifetime of ²⁴₁₀Ne, ²⁸₁₂Mg, ³⁰₁₂Mg, ³²₁₄Si, ³⁴₁₄Si, ⁴⁸₂₀Ca, ⁴⁹₂₁Sc cluster radioactivity in ¹²⁷I have been achieved.     

Full destruction characteristics of light and heavy nuclei with 3.7-158A GeV energies

The full destruction (FD, that implies the disintegration into singly and doubly charged fragments only) characteristics are presented for some light nuclei ( ₆ ¹² C, ₈ ¹⁶ O, ₁₀ ²² Ne, and ₁₄ ²⁸ Si) with an energy of 3.7A GeV and heavy projectiles ₇₉ ¹⁹⁷ Au (10.7A GeV) and ₈₂ ²⁰⁸ Pb (158A GeV) interacting with target nuclei in a photoemulsion. It is shown that (i) the average number of fragments, the realization of various fragmentation channels, and the degree of crushing for light projectiles substantially depend on the charge of a residual nucleus and on the mass of a target nucleus; (ii) the FD probability for residual nuclei with the same charge, as well as the multiplicity of fragments for the same impact parameter of heavy nuclei, are independent of the energy; and (iii) the integral distribution of transverse momenta of doubly charged fragments is described by two exponents (the logarithmic plot exhibits a break).     

14C cluster emission: a tool for the study of nuclear structures

A brief survey of the¹⁴C cluster emission of different radium isotopes will remind the first evidence for an odd-even effect in¹⁴C radioactivity. The discovery at the I.P.N. Orsay, of a fine structure in the¹⁴C emission of²²³Ra enhanced the development of this new investigation field. The qualitative interpretation of the favoured transitions to the first two excited states of the²⁰⁹Pb daughter nucleus offers a new possibility to better understand nuclear structures of heavy deformed nuclei. For instance, an accurate determination of the energy of the¹⁴C clusters emitted by²²⁵Ac and²²¹Fr must allow to improve our knowledge of ground state configurations of these nuclei.