建立激光同步辐射源的初步探讨

进行了基于正对以及离轴几何条件下,电子与激光束间Compton / Thomson散射的激光同步辐射源的初步探讨。运用现有的直线加速器技术以及高功率、高重复频率激光器技术可以为构建超短脉冲的高亮度、准单色、可调谐的X和γ射线源开辟一条新途径。     

多种优化试剂显现潮湿纸张表面潜在手印的比较研究

复杂条件下潜在手印的发现及显现提取一直以来是刑事技术领域研究的热点和难点,尤其是潮湿或水中浸泡客体表面的潜在手印,往往因为环境条件的影响而无法使用常规的显现方法。因此,对于这类疑难条件下潜在手印的显现研究成为亟待解决的问题。本文分别对比了尼罗红、尼罗蓝、物理显影液三种可用于潮湿客体表面潜在手印显现的优化试剂,并对其可靠性、灵敏度及使用条件进行了详细的论证分析,为实战工作中疑难条件下潜在手印的显现提出了可靠的处理方法。     

Isoscaling of the Fission Fragments with Langevin Equation

The Langevin equation is used to simulate the fission process of ^112Sn ^112Sn and ^116Sn ^116Sn. The mass distribution of the fission fragments are given by assuming the process of symmetric fission or asymmetric fission with the Gaussian probability sampling. The isoscaling behaviour has been observed from the analysis of fission fragments of both the reactions, and the isoscaling parameter α seems to be sensitive to the width of fission probability and the beam energy.     

直流大气压电晕放电电子密度的光谱研究

利用自制针—板式放电装置,在大气中进行电晕放电实验。用发光区域照片光斑的大小,讨论了电晕层厚度与电源电压的关系。在相同针板间距下,电晕层厚度随着电压的升高而增大;在相同电压下,电晕层厚度随着针板间距的增大而减小。由于高能电子密度能够通过氮分子第二正带系337.1 nm的光谱强度大小反映,因此对氮分子第二正带系337.1 nm谱线的强度用发射光谱法进行了测量。实验结果发现在针尖附近高能电子密度最大,并且高能电子密度随电压的升高而增大;电压一定时,高能电子密度随针板间距的增大而减小。在针板间距和电源电压不变的情况下,高能电子密度随针尖曲率半径的减小而增大。     

非均匀波导中的声聚焦

理论研究了声波在非均匀波导中的空间聚焦问题,利用多模态导纳法构建波导内任意位置处声压与入射声压在模态域的映射关系,计算使声波聚焦于空间某位置时的最佳入射波,并画出了相应的聚焦声场.研究了三种非均匀情况:水平变截面波导、含散射体波导以及声速垂直变化波导.结果表明,当输入最佳入射波时,在非均匀波导中可以产生良好的单点或多点声聚焦效果,声波的聚焦过程充分地利用了波导结构及介质非均匀性对声波的散射作用.     

基于上海激光电子γ源的天体核合成关键反应12C(α,γ)16O的反应率研究

正在研制的上海激光电子γ源是MeV量级的高品质γ光束线站，基于该装置可以开展一系列核天体物理实验, 从而更准确的确定各天体核合成反应的反应率. 本文研究了天体核合成中的关键反应¹²C(α,γ)¹⁶O的反应率. 根据多组实验和理论截面数据分别计算了反应率, 并给出了这些反应率计算结果的平均值和统计误差. 根据该结果拟合了理论反应率的解析形式, 确定了新的参数. 进而给出俘获反应¹²C(α,γ)¹⁶O在He燃烧环境下的反应率和误差, 并讨论了电子屏蔽效应对天体反应率的修正.     

康普顿背散射技术对贮存环电子束诊断及其应用 II贮存环电子束的极化度测量

简单介绍以激光 电子康普顿背散射原理为基础建立的康普顿背散射极化仪,采用它能实时、非破坏性地监测电子束的极化.该项工作可作为上海激光电子γ源(SLEGS)低能γ束应用研究的内容之一.     

Isoscaling in Statistical Sequential Decay Model

A sequential decay model is used to study isoscaling, i.e. the factorization of the isotope ratios from sources of different isospins and sizes over a broad range of excitation energies, into fugacity terms of proton and neutron number, R21（N, Z） = Y2（ N, Z）/Y1（ N, Z） = Cexp（αN -βZ）. It is found that the isoscaling parameters α and β have a strong dependence on the isospin difference of equilibrated source and excitation energy, no significant influence of the source size on α andβ has been observed. It is found that α and β decrease with the excitation energy and are linear functions of 1/T and △（Z/A）2 or△（N/A）2 of the sources. Symmetry energy coefticient Gsym is constrained from the relationship of a and source △（Z/A）2, /3 and source △（N/A）2.     

A new probe of neutron skin thickness

The correlation between neutron-to-proton yield ratio (R_np) and neutron skin thickness (δ_np) in neutron-rich projectile induced reactions is investigated within the framework of the Isospin-Dependent Quantum Molecular Dynamics (IQMD) model. The density distribution of the Droplet model is embedded in the initialization of the neutron and proton densities in the present IQMD model. By adjusting the diffuseness parameter of neutron density in the Droplet model for the projectile, the relationship between the neutron skin thickness and the corresponding R_np is obtained. The results show strong linear correlation between R_np and δ_np for neutron-rich Ca and Ni isotopes. It is suggested that R_np may be used as an experimental observable to extract δ_np for neutron-rich nuclei, which is very interesting in the study of the nuclear structure of exotic nuclei, the equation of state (EOS) of asymmetric nuclear matter and neutron-rich matter in astrophysics, etc.     

Investigation of Exotic Structure of the Largely Deformed Nucleus ^23A1 in the Relativistic-Mean-Field Model

A candidate for proton halo nucleus ^23A1 is investigated based on the constrained calculations in the framework of the de[ormed relativistic mean tield (RMF) model with the NL075 parameter set. It is shown by the constrained calculations that the ground state of ^23A1 has a large deformation that corresponds to the prolate shape. With that large deformation, the non-constrained RMF calculation predicts that there appears an inversion between the 2s1/2 [211] and ld5/2 [202] shells. The valence proton of ^23A] is weakly bound and occupies 2s1/2 [211] and ld5/2 [202] with the weights of 56% and 29%, respectively. The calculated RMS radius for matter is in agreement with the experimental one. It is also predicted that the difference between the proton RMS radius and the neutron one is very large, This suggests that there exists a proton hMo in ^23Al.