The analysis of physics principles of neutron backscattering technique and Monte Carlo simulation were presented for assessment of landmine detection by neutron backscattering technique.The results are greatly valuable for future research and engineering.

The advantages and characteristics of detection of hidden explosives and radioactive materials by nuclear technologies are explained in this paper. The active neutron interrogation technology and their application to detection of explosives are introduced in detail. The non-neutron interrogation technology by gamma method, the commercialized industry neutron sources and gamma ray detectors and their advantages and disadvantages respectively in security application are summarized respectively. The security problem of two typical hidden explosives are discussed with 11 characteristics of a perfect detecting system of explosives. The current research progress in association with particle imaging and fast-pulse neutron system and the passive method to detection of radioactive materials are briefly described. Finally, the paper points out that for detection of hidden explosives and radioactive materials it is necessary to use different technologies for different scenes and targets or use combined technologies.

运用相对论有效原子实模型RECP和B3LYP方法计算了UH和UH2的结构.并在此基础上, 利用多体项展式理论方法, 导出三原子分子UH2的解析势能函数.根据UH2势能函数, 采用准经典的Monte-Carlo轨线法研究了U+H2体系的碰撞过程.依据反应截面与能量之间的关系, 指出U+H2(v = j = 0)是无阈能反应, 主要生成UH2, 而反应H+UH(v = j = 0)生成UH2的反应截面相对来说要小得多, 可以忽略.如此证明铀与氢气反应生成UH3的中间产物是UH2, 而不是UH.这些结果为金属铀的抗氢化腐蚀研究提供了理论基础.

介绍了CFBR-Ⅱ堆泵浦3He-Ar-Xe体系1.73μm波长激光小信号增益和泵浦效率的实验研究.在脉冲峰热中子注量率为6.9×1014cm-2.s-1、3He、Ar、Xe气体的比例为80.2:19.3:0.5,总压强为8.3×104Pa时,采用透射率从1.7%到10%的6个谐振腔输出镜均获得了激光输出.在谐振腔输出镜透射率为7%时,得到了激光脉冲峰功率为45mW,其对应的激光泵浦效率为1%.在此基础上,利用Rigroa分析方法拟合出3He-Ar-Xe体系激光的小信号增益为0.24%/cm,饱和光强为36W/cm2.

Development of nuclear pumped lasers (NPL) in the CFBR-Ⅱ reactor is briefly reviewed. The results ofthe two NPL experiments in CFBR-Ⅱ reactor are described. The first one focused on the principle ofnuclear pumped laser, and 4-mW laser output power achieved. The second NPL experiment focused onthe small signal gain and the efficiency of the nuclear pumped He-Ar-Xe gas mixture at 1.73 μm. Themaximum laser power measured to be 45 mW when thermal neutron flux rate is 6.9 × 10 14 cm-2 @ s-1.The small signal gain at 1.73μm by the Rigrod analysis method is to be 0.24%.cm-1, and the saturationintensity is fitted to be 36 W/cm2.

Using density function theory (B3LYP) method, a variety of equilibrium structures for the OUH system have been optimized. Its most stable structure, the dissociation energy and harmonic force constants have been obtained. The Murrell-Sorbie potential energy functions and spectrum data of diatom molecules UH and UO in OUH have been derived. The analytical potential energy function for the ground state OUH (X̃4A′) was derived using the many-body expansion method. The potential energy surfaces reflect accurately equilibrium geometry of OUH. The results imply that the U + OH, O + UH and H + UO are exothermic reactions without threshold.

基于多体展式方法所导出的HHF体系的分析势能函数,用准经典的Monte-Carlo轨迹法研究了H+HF(v′,J′)→H+HF(v″,J″)振转非弹性碰撞过程.结果表明:H原子对HF在低能和高能范围对高J转动能级有驰豫作用,对HF的振动能级的粒子分布有一定影响.

根据所得到Kr-HF体系的两种弱结合分子的结构参数、离解能和谐性力常数,采用多体项展式方法,对Kr-HF体系的性质和势能函数重新进行了研究.导出KrHF(X1Σ+)基态分子的分析势能函数,获得KrHF (X1Σ+)体系的势能面.考察了这个势能函数的基本性质,准确地复现出Kr-HF分子的平衡结构特征.

Based on ArS2 analysis potential function, which was calculated using ab initio MP2/6-31+G method and multi-body expansion theory, the dynamic proces s has been studied. The results indicated that the restraint of Ar and S2 due to physical adsorption, and the reaction of Ar and S2 is pri marily non-elasticity collision at a serial set of energies. Through analysis of inelastic collision products, it is shown that Ar atom can excite S2 (Ｘ3Σ－g) to S2(B3Σ－u) gradually.

基于多体展式方法所导出的NeHF(X1Σ+)的分析势能函数,用准经典的Monte-Carlo轨迹法研究了Ne+HF(v′,J′)→Ne+HF(v″,J″)振转非弹性碰撞过程.结果表明:Ne对HF的振动能级的粒子分布影响较大,在较低相对平动能下,对HF转动能级有驰豫作用.

The wavelength dependence of absorption of laser has been studied experimentally in the Shen Guang type and Xing Guang type laser facility with the gold disks at a chosen angle of incidence. The experiments show that inverse bremsstrahlung absorption is the main absorption mechanism, and the absorption increases when laser wavelength decreases. Although the absorption of 0.351 μm laser at 10 ° angle of incidence is higher than that of others, the absorption of 0.351 μm laser at 45 ° angle of incidence is only 75% and scattered light is up to 25%.

The quasiclassical trajectories have been calculated for H 2F and H 2Cl + system using analytical potential energy functions based on many-body expansion method. The relationships between HF vibrational population distributions and the relative collision energy E T have been presented, from which the population inversion between V��=2 and V��=0 of HF is quite remarkable from 8 to 42kcal/mol -1 of E T. The dependence of HCl vibrational level populations with relative translational energy of reactants HCl is also discussed for two of H 2Cl + channels. It is obvious that there are vibrational population inversion of HCl level for exothermal reaction Cl+H 2 + ��HCl+H +, and normal population distribution of HCl level for proton exchange reaction H ++HCl ��HCl+H +.

报道了０．５３μｍ高功率激光辐照金盘靶产生的受激拉曼散射光光谱和散射光能量角分布，由散射光角分布计算的散射光能量与实验通过打靶透镜测得的受激拉曼散射能量不符，而且角分布的实验结果与受激布里渊散射理论也不符。实验结果分析表明，散射主要是未被等离子体充分吸收的激光在弯曲的临界密度面上的反射

The angular distribution of scattered lights from interaction of 0.53 micrometers laser light with Au disks was reported. The experimental results show that the angular distribution is different from what stimulated Brillouin scattering (SBS) theory predicts, and the stimulated Raman scattering (SRS) energy is much lower than that of the scattered lights, therefore, neither SRS nor SBS can be the mechanism of producing these scattered lights. The scattered lights from interaction of 0.53 micrometers laser light with Au disks can mainly come from specular reflection of curved plasma surface with critical density.

The spectra of helium & krypton excited by alpha-particles (-5.5MeV) emitted from 238Pu had been measured by using a home-made single-photon counting system. Thirteen spectral lines of helium between 370.0-720.0nm were identified, five lines of them belong to HeI's spectra, the others were the vibronic spectra of helium moleculars; and seven spectra lines of krypton between 400.0-600.0nm were observed. The spectra intensity varying with gas pressure had been given for He and Kr, respectively. The possible atomic & molecular processes by alpha-particles impaction were discussed.

Au disk targets were irradiated with -0.8 ns, 1.05 and 0.53 μm laser. The intensity and angular dependence of absorption were studied experimentally. The experimental results of absorption by laser-produced plasma are introduced in this paper. The measured absorption with plasma calorimeters accord with one-dimension planar simulation. The experiment and theory show that collision absorption is the main absorption mechanism. A scaling law of absorption has been suggested based on the careful analysis of the experimental results.