中国先进研究堆中子科学平台发展现状及展望

依托中国先进研究堆(CARR)高通量中子源,建成了初具规模的中子科学平台,具备中子散射、中子成像和中子活化分析等多种研究技术。其中,中子散射技术包括中子衍射、小角中子散射及中子反射、非弹性中子散射,可以用于分析材料微观结构和动力学性质;热中子成像和冷中子成像可以用于材料内部缺陷等无损检测;中子活化分析系统可以用于物质内核素成分分析。目前已建成和在建中子谱仪共计19台,并初步配备了样品环境装置,为相关应用研究提供了条件基础,可为我国物理、化学、材料科学、生命科学、能源和环境等领域基础研究及工业应用提供重要技术支撑。CARR中子科学平台始终坚持合作共享对外开放的宗旨,将继续为国内外用户提供优质中子技术,服务基础科学前沿和国家重大创新需求研究。     

内爆驱动式超高速发射技术的初步研究

为获得10 km/s左右的超高速发射能力,以内爆发射器为研究对象,利用AUTODYN 2D软件对口径为8 mm的内爆发射器进行有限元仿真分析,获得了典型状态下的弹丸发射速度。研制了口径为8 mm的内爆发射器,并在压缩管中填充5 MPa氦气进行实验,分别获得了0.55 g铝合金弹丸7.95 km/s和0.37 g镁合金弹丸10.28 km/s的发射速度,与有限元仿真计算结果的速度偏差分别为15.3%和3.7%。结果表明,设计的内爆发射器具备10 km/s发射能力,满足空间碎片撞击和防护研究的超高速发射需求。     

气体扩散方程解析解及在测定分子间势能的应用

设计了一新颖的分子动理论实验装置,根据求解在约束条件下的气体扩散方程的解析解和气体分子在升华时会对容器底部产生作用力的特点,设计了一种新颖简单的实验器材来测量分子间相互作用的势能,其实验曲线符合理论数据,误差分析后的补偿曲线所得结果可较为精确地与理论结果吻合。本实验常温下即可进行,且精度较高,适合快速材料性质测定及大学物理教学,以解决大学物理演示实验课关于学气体动理论的实验数量较少,且往往只涉及对热学微观过程的宏观模拟,而很少涉及气体动理论的实验,导致学生学习不够深入的问题。有利于学生对分子运动学问题的深入探索。     

石墨炉原子吸收光谱法测定化探样品中痕量银的不确定度评定

运用测量不确定度评定与表示的理论,分析了用石墨炉原子吸收光谱法测定化探样品中银的不确定度.指出了不确定度分量由称样质量、标准溶液配制、校准曲线拟合、测量重复性、试液定容体积组成.对各个分量进行量化,合成得到测量结果的标准不确定度,通过乘以95％概率下的扩展因子2,获得测量结果的扩展不确定度.     

圆偏振飞秒激光脉冲与低压氙气体靶相互作用软X射线辐射实验研究

利用平场光栅谱仪,分别在2和3 kPa的低气压下,测量了脉宽35 fs的圆偏振超强超短激光脉冲与5 mm长氙气体靶相互作用产生的波长在5～60 nm范围内的离子谱线。2 kPa时最强的跃迁为XeⅧ：4d105s(2S_1/2)—4d95s5p(2P_3/2)的17.085 6 nm线,3 kPa时最强的跃迁为11.343 nm的XeⅦ 4d105s2(1S0)—4d95s25f(3P₁)跃迁。两种气压下,Xe均被电离到XeⅦ,XeⅧ,XeⅨ态。     

Advances in micro-perforated panel absorbers

Theoretical and experimental investigations on the performance of micro-perforated -panel absorbers are reviewed in this paper. By reviewing recent research work, this paper reveals a relationship between the maximum absorption coefficient and the limit of the absorption frequency bandwidth. It has been demonstrated that the absorption frequency bandwidth can be extended up to 3 or 4 octaves as the diameters of the micro-holes decrease. This has become possible with the development of the technologies for manufacturing micro-perforated panels, such as laser drilling, powder metallurgy, welded meshing and electro-etching to form micrometer order holes. In this paper, absorption characteristics of such absorbers in random fields and in high sound intensity are discussed both theoretically and experimentally. A new absorbing structure based on micro-perforated-panel absorbers demonstrate experimentally high sound absorption capability. This review shows that the micro-perforated-panel absorber has potentials to be one of ideal absorbing materials in the 21st century.     

SILEX-1装置上等离子体尾场加速电子初步实验

激光等离子体加速电子机制可以产生准单能的高能电子束, 近年来成为国际上的研究热点. 中国工程物理研究院激光装置已经能够达到286TW的输出功率, 为国内在该领域的研究提供了实验条件. 文章介绍了在SILEX-1装置上开展的激光等离子体加速电子的初步实验, 并对测得结果进行讨论, 为下一步实验的进行提供了准备条件.     

Evolution of Bond-Order-Wave Phase in One-Dimensional Mott Insulators

In this paper, by using the level spectroscopy method and bosonization theory, we discuss the evolution of the bond-order-wave （BOW） phase in a one-dimensional half-filled extended Hubbard model wlth the on-site Coulomb repulsion U as well as the inter-site Coulomb repulsion V and antiferromagnetic exchange J. After clarifying the generic phase diagrams in three limiting cases with one of the parameters being fixed at zero individually, we find that the BOW phase in the U-V phase diagram is initially enlarged as J increases from zero but is eventually suppressed as J increases further in the strong-coupling regime. A three-dimensional phase diagram is suggested where the BOW phase exists in an extended region separated from the spin-density-wave and charge-density-wave phases.     

Optical Planar Waveguides in KTiOPO4 Crystals by MeV Oxygen Ion Implantation

We report on the optical planar waveguide formation in KTiOPO4 crystals by single or double oxygen ion implantation at energies of 2.4-3.0 MeV and doses of 1015 ions/cm^2. The dark-line spectroscopy properties are investigated by a prism-coupling method. With an effective refractive index method, the refractive index profiles of the waveguides are reconstructed. The program code TRIM＇98 （transport of ions in matter） is used to simulate the implantation process of oxygen ions into the KTiOPO4 crystal. It is found that an inherent relationship exists between the nuclear damage and the refractive index changes induced by the ion-beam implantation.     

蛋白质对纳米铕岛膜表面荧光的增强作用

将经硫辛酸修饰的铕纳米颗粒和蛋白质固定在石英玻璃表面或胶原蛋白隔离的石英玻璃表面,研究蛋白质对纳米铕岛膜荧光的增强作用.研究结果发现,在275nm激发波长下,铕纳米岛膜的荧光光谱与铕纳米颗粒溶液的荧光性质相似,且微量蛋白质的加入可以使铕纳米岛膜的荧光强度增强,但被石英玻璃片吸附后,铕纳米岛膜以及铕-蛋白质体系的荧光发射峰的位置由378.8nm红移至420nm,且胶原蛋白隔离铕纳米岛膜和滴加微量BSA蛋白质的荧光光谱相似,但荧光强度没有发生明显变化.