Test of Determination of (p,γ) Astrophysical S-Factors Using the Asymptotic Normalization Coefficients from Neutron Transfer Reactions

The asymptotic normalization coefficients （ANCs） for the virtual decay ^17 O→^16 O＋n are derived from the angular distributions of the 16 O（d, p）^17O reaction leading to the ground and first excited states of ^17O, respectively, using the distorted wave Born approximation and the adiabatic wave approximation. The ANCs of ^17F are then extracted according to charge symmetry of mirror nuclei and used to calculate the astrophysical S-factors of ^16 O（p, γ）^17 F leading to the first two states of ^17 F. The present results are in good agreement with those from the direct measurement. This provides a test of this indirect method to determine direct astrophysical S-factors of （P, γ） reaction. In addition, the S-factors at zero energy for the direct captures to the ground and first excited states of ^17 F are presented, without the uncertainty associated with the extrapolation from higher energies in direct measurement.     

一款小角X射线散射测量专用样品旋转装置

在小角X射线散射实验中经常需要对各向异性结构样品进行旋转。针对传统样品架为固定方式,旋转调整困难的特点,本文设计了一款小角X射线散射专用的样品旋转装置。该装置主要由步进电机、高精度回转轴承、传动系统、样品架、控制器及配套软件等组成,它具有结构简单、回转精度高、可远程控制的特点。在北京同步辐射小角X射线散射实验站应用该样品旋转装置对石墨纤维样品进行了测试,验证了该装置的可行性。     

Enhancement of β^＋-Decay Rate of ^22Na in Metal Pd at Low Temperature

Temperature dependence of nuclear decays in metallic environments is a controversial issue. We measured the temperature dependence of the β^＋-decay half-life of ^22Na implanted into the metal host of palladium. It is found that the β^＋-decay half-life of ^22Na in the metal Pd cooled to T = 15 K is shorter by 0.46（14）% than that at room temperature. The result is consistent in sign with, but dearly smaller than, the estimated one by the Debye model.     

利用小角X射线散射技术研究煤干馏过程中的孔隙结构变化

煤干馏是煤炭高效利用的重要途径之一。同步辐射小角X射线散射(Small Angle X-Ray Scattering,SAXS)技术是研究煤干馏过程中内部孔隙结构变化的常用手段。本文利用SAXS对山西余吾烟煤干馏过程(100~1200℃,温度梯度100℃)进行了表征,并对分形维数和粒径分布的变化进行了分析。结果发现煤干馏过程中,散射图像类似,具有各向同性特征,始终保持表面分形结构,且分形维数总体上呈现增大的趋势;随着煤干馏温度的升高,粒度分布发生了显著变化,充分反映了煤在不同干馏阶段的结构特征,对后续的煤炭研究具有一定的指导意义。     

高能电子照射对金刚石中缺陷电荷状态的影响

金刚石经电子辐照后会形成大量的点缺陷, 而这些缺陷很多都是带有电荷的. 提出一种用于研究缺陷电荷状态的新思路, 即利用扫描电子显微镜(SEM)的高能电子照射辐照区域, 通过比较SEM 照射前后的低温光致发光光谱, 为缺陷电荷状态的确定提供了一些依据. 关键词： 金刚石 点缺陷 电荷状态     

Radius of ^9C from the Asymptotic Normalization Coefficient

The asymptotic normalization coefficient (ANC) of^9C=^8B p deduced from S Li(d, p)^9 Li reaction is used to obtain the root-mean-square (rms) radius of the loosely bound proton in the ^9C ground state. We obtain (r^2)1/2 = 3.61 fm for the valence proton, which is significantly larger than the matter radius of ^9C. The probability of the valence proton outside the matter radius of ^9C is greater than 60%. The present work supports the conclusion that ^9C has a proton halo structure.     

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

The angular distributions of the charge exchange reaction ^1H(^6He,^6Li)n were measured in reverse kinematics with a secondary ^6He beam at the energy of 4.17 A MeV.The data were analysed in the context of a microscopic calculation.It is shown that both the ground state of ^6He and the second excited state of ^6Li(3.563MeV,0^ ) have a halo structure.     

同步辐射二维小角X光散射实验装置的建立与应用

与一维小角散射实验法相比,二维小角X光散射实验法可用于研究非球对称的体系,即可探测物质中取向体系的颗粒度(或孔径)的变化、颗粒(或孔)形状的变化等信息.介绍了北京同步辐射装置二维小角X光散射实验设备的建造及所建立的分析方法,并用于研究不同活化剂条件下制备出来的沥青基活性炭纤维中孔分布的变化,得到了炭纤维中的孔的平均体积随活化剂中NH3含量的降低而变大的结论.     

一种新型的光纤陀螺仪信号采集方法

针对惯性导航系统中，光纤陀螺的动态测量范围宽、精度高、实时性强的要求，设计了一种新型的数据采集方法，该方法具有精度高、量程宽、速度快的优点。通过与惯性导航系统中光纤陀螺的几种常用的数据采集方法进行分析比较，介绍了各自的优缺点，并着重介绍了这种方法的电路实现。     

我国同步辐射小角X光散射装置

小角X光散射是当X光照射到物质上时发生的在原光束附近小角度范围内的电子相干散射,凡是存在纳米尺度的电子密度不均匀区的物质均会产生小角X光散射现象,因此它是表征纳米、多孔材料结构的理想手段。普通X光源产生的X光强度弱,限制了小角X光散射的应用,采用同步辐射为X光源,则可以大大提高X光强度。目前我国已建立同步辐射小角X光散射站,本文对其装置进行了介绍。