质子滴线核~(12)N在~(28)Si靶上的核反应总截面测量

描述了50.4 MeV/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σr实验研究,结果发现12N的反应总截面σr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.     

中能8B和9C与Si反应总截面的测量

能量为75MeV/u的¹²C初级束轰击2mm厚的初级Be靶,并利用RIBLL从弹核碎片中分离出54.2MeV/u质子滴线核束8B和61.1MeV/u的⁹C,再轰击Si靶,用透射法测量了它们与Si的反应总截面σ_R.并应用Glauber模型进行理论计算,分析结果表明⁸B和⁹C都可能具有质子晕结构.     

质子滴线核17Ne在Si靶上反应总截面的测量

描述了在兰州放射性次级束流线上用80MeV/u的2?0?Ne轰击Be靶产生出理论上预言有奇异结构的17Ne的次级束流,并用它轰击Si靶,测量它的反应总截面并与其相邻的核相比较,发现截面值没有增大的现象.利用微观的Glauber模型进行了计算,理论计算和实验结果符合很好,确认其没有奇异结构.     

P同位素的质子滴线核研究

研究了在相对论平均场近似下P同位素的滴线核的性质,首先在理论上探讨了25P作为P的滴线核存在的可能性及其可能具有的质子晕结构,然后给出了在兰州放射性束流装置上25P的实验鉴别结果. Great progress was made on the study of P isotope both in theory and in experiments, but the final conclusion about the dripline of P isotope has not been made. In this article the properties of P isotope was studied in the frame work of relativistic mean field (RMF). First the probability of 25P as the dripline nuclei of P isotope and the proton halo structure of 25P was discussed, and then the RIBLL experiental result of 25P is presented.     

22MeV质子在28Si上弹性及非弹性散射微观分析

通过22MeV质子与²⁸Si的散射实验,测量了质子弹性散射和在21+(1.78MeV)及41+(4.62MeV)激发态上的非弹性散射微分截面.采用动量空间DWBA理论,利用由电子散射实验得到的核结构信息,和低能区的密度依赖、能量依赖的复数有效相互作用对数据进行了分析.在没有任何可调参数和归一因子的情况下,理论计算与实验数据的符合情况是令人满意的.     

质子滴线核8B的实验研究进展

质子滴线核8B的最后一个质子的分离能只有0.137 5 MeV,被认为是最有可能具有质子晕结构的候选核之一,对其反应机制和奇特结构的研究吸引了人们的关注。针对8B的奇特结构和反应机制研究是一个非常有趣的课题,研究人员在包括反应截面、碎裂产物动量分布宽度、电四极矩、熔合截面及弹性散射等方面开展了大量的工作。但是8B的研究至今仍不够充分,需要从理论和实验上对其进行更深入的研究。     

质子滴线附近的新核素129Pm

通过重离子引起的融合蒸发反应⁹²Mo(⁴⁰Ca,p2n)合成了稀土区未知核素¹²⁹Pm,并且配合氦喷嘴快速带传输系统利用X-γ符合方法对它进行了首次鉴别.实验观测到了经¹²⁹Pm的(EC+β⁺)衰变产生的对应于子核¹²⁹Nd中5/2^－→1/2^－跃迁的一条99keV γ线.根据这条99keV γ线的时间衰变曲线,提取出¹²⁹Pm的半衰期为(2.4±0.6)s.     

进一步指认近质子滴线核129Pm的衰变

2004年曾报道过利用⁴⁰Ca＋⁹²Mo融合蒸发反应产生了近质子滴线新核素Pm,并首次观测到它(EC+b+)衰变产生的能量为99keV的γ射线. 为了进一步确认上述指认，以下提供了三方面的新证据：1)在164－190MeV能量范围内测量了99keV衰变γ射线的激发函数;2)进行了交叉反应 ³⁶Ar＋⁹⁶Ru的实验,观察到了相同的99keV衰变γ射线；3)用Woods-Saxon Strutinsky方法计算了¹²⁹Pm的核势能面，其基态自旋宇称被预言为5/2^－，所以¹²⁹Pm的(EC＋b＋)衰变有利于馈送到子核¹²⁹Nd的5/2_－的低位态，这也与前期报道相符.     

对质子滴线核19Na的β延迟质子衰变的首次观察

由²⁰Ne(P,2n)¹⁹Na反应,对质子滴线核¹⁹Na进行了研究,实验在中国科学院高能物理研究所质子直线加速器上进行,首次观察到了¹⁹Na的β延迟质子衰变,测定其质子能量为1.10±0.08MeV,半衰期为47±20ms,它相应于¹⁹Na基态到¹⁹Ne的7.62MeV、T=3/2同位旋相似态的超允许β跃迁和由此态到¹⁸F基态的级联质子衰变.     

46.7MeV/u 12C诱发核反应中的双质子干涉研究

本文讨论了46.7MeV/u ¹²C+⁵⁸Ni,¹¹⁵In,¹⁹⁷An实验中双质子干涉的研究结果,研究了零寿命Koonin模型中核力、库仑力及费米统计对关联函数的影响,并从实验中提取了发射源的半径参数r₀,实验发现r₀随着靶核质量的增加而增加,实验中还研究了发射源的大小与两个关联粒子能量和E₁+M₂的关系,得出的r₀值随着E₁+E₂的增加而减少,反映了高能质子主要来源于反应的早期.     

核反应总截面和奇异结构研究

本总结了晕和皮等奇异核子结构研究的现状,介绍了发现晕和皮现象的实验证据。然后集中介绍了利用奇异核反应总截面的实验测量和理论模型,从中提取奇异核物质半径,核内核子分布以及介质中的核子－核子碰撞截面等重要信息,我们将特别强调通过实验测量和理论模型之间的联系来研究奇异结构性质。     

The properties of halo structure for 17B

The total reaction cross section (1724 ± 93 mb) of ¹⁷B at the energy of 43.7 A MeV on C target has been measured by using the transmission method at the Radioactive Ion Beam Line in Lanzhou (RIBLL). Assuming ¹⁷B consists of a core ¹⁵B plus two halo neutrons, the total cross section of ¹⁷B on C target was calculated with the zero-range Glauber model, where double Gaussian density distributions and Gaussian plus HO density distributions were used. It can fit the experimental data very well. The characteristic of halo structure for ¹⁷B was found with a large diffusion of the neutrons density distribution. Supported by the National Natural Science Foundation of China (Grant Nos. 10475098, 10605033 and 10221003), the Chinese Academy of Sciences (Grant Nos. CXTD-J2005-1 and KJCX2-SW-N18), and Hundred Talent Project of CAS (Grant No. 0501080BR0)     

MEASUREMENT OF L-SHELL IONIZATION CROSS SECTIONS FOR NIOBIUM BY ELECTRON IMPACT

L-shell ionization cross sections of Nb by electron impact in the energy range from 3 to 40 keV have been determined with a Si(Li) X-ray detector. Influence of reflected electrons from backing on the measurement was corrected using an electron transport model. The experimental results are compared with theoretical calculations of Gryzinski and McGuire.     

中子与56Fe反应的理论计算

应用光学模型、核内级联模型、激子模型（含改进的Iwamoto-Harada模型）、统一的Hauser-Feshbach理论以及扭曲波玻恩近似理论,对入射能量在20 MeV以下中子与56Fe非弹性散射反应的γ产生截面、分立能级截面和总的非弹性散射截面进行计算,并与最新实验数据以及来自ENDF/B-VII、JEFF-3.1和JENDL-4库的评价数据进行比较和分析。结果显示,理论计算结果与实验数据符合较好,并且对于有些激发态的非弹性散射截面我们的计算结果优于ENDF/B-VII,JEFF-3.1和JENDL-4库的评价结果。The gamma production, level production and total inelastic scattering cross sections are calculated at incident neutron energy below 20 MeV. The optical model, the intra-nuclear cascade model, the exciton model (including improved Iwamoto-Harada model), the uni ed Hauser-Feshbach theory and the distorted wave Born approximation theory are used. Theoretical calculated results are compared with the recent experimental data and other evaluated data from ENDF/B-VII, JEFF-3.1, and JENDL-4. It is found that our calculated results agree with the experimental data and the calculated results for some level cross sections are more consistent with the related experimental data than the results from ENDF/B-VII, JEFF-3.1, and JENDL-4 data base.     

Beta-ray spectra of 12B and 12N and conserved vector current

In order to investigate spectral shape factors of ¹²B and ¹²N, we make a new formalism of β-decay theory, where the radial wave functions of leptons are treated with no approximation and, therefore, the nuclear matrix elements are electron-energy dependent. With this formalism we can show strong support for the conserved vector current hypothesis in analyzing the experimental data which were given by Wu, Lee and Mo in 1963 and revised by them in 1977 using the latest experimental results on the end-point energies and branching ratios of the inner β-groups, in addition to the correct Fermi functions for the positron. In fact, the average slopes of the spectral shape factors for ¹²B and ¹²N are in excellent agreement with those in our theory. Recent experimental data given by the Heidelberg group are also in good agreement with the theory if we analyze the difference of the average slopes for ¹²B and ¹²N. There are, however, small discrepancies with the theory in their individual values. The relation of the present formalism with traditional theories of β-decay is discussed.     

Global optical model potential describing 12C-nucleus elastic scattering

We construct a new global optical model potential to describe the elastic scattering of ¹²C. The experimental data of elastic-scattering angular distributions and total reaction cross sections for targets from ²⁴Mg to ²⁰⁹Bi are considered below 200 MeV within the framework of the optical model. The results calculated using the derived global optical potential are then compared with the existing experimental data. The reliability of the global optical potential is further tested by predicting the elastic scattering data out of the mass and energy ranges, within which the global potential parameters are determined, and reasonable results are also obtained.     

在独立α集团模型下对敲出反应16O(p,pα)12C和16 O(α,2α)12C的研究

在独立α集团模型下，利用扭曲波冲量近似(DWIA)，计算了实验室系下入射能量为101.5MeV 的敲出反应¹⁶O(p，pα)¹²C和实验室系下入射能量分别为90Me V和140MeV 的敲出反应¹⁶O(α,2α)¹²C.得到的反应截面和谱因子与实 验数据基本符 合，比用壳模型的结果有了一定的改进，表明独立α集团模型能较好地描述α集团敲出反应 的机理. 关键词： α集团模型 敲出反应 反应截面 谱因子     

Time-dependent Hartree-Fock calculations for 14N + 12C reactions

We present Time-Dependent Hartree-Fock calculations for the massasymmetric system ¹⁴N + ¹²C in the range 20 ? E_cm ? 114. A simplified effective interaction of the Skyrme form has been used and the orbital angular motion of the ions has been treated in the rotating frame approximation. The overall magnitude of the calculated fusion cross-section is in agreement with experiment. The calculated differential cross section for direct inelastic reaction products is proportional to ${}^1\text{sin θ}$. This is in contrast to the exponential decrease observed experimentally.     

光学模型与ADS靶的反应截面

利用核反应中光学模型理论,对质子入射能量从阈能到450MeV,加速器驱动的洁净核能系统的靶材209Bi、208Pb、202Hg、197Au、184W、181Ta与质子的反应进行了研究.给出了两套与实验数据符合很好的光学势参量;预言了质子与Bi、Pb、Hg、Au、W、Ta的反应截面;对现有的实验数据进行了理论验证.