27,28P+28Si总反应截面增强及可能相关的机制

测量了27,28P和相应同中子异位素在28Si靶上的中能反应截面.测得N=12和13同中子异位素的反应截面在Z=15处突然增大.对Z≤14同中子异位素和28P的实验数据结果可以用改进的光学极限近似的Glauber理论很好地描述.28P的反应截面能够用扩大核芯以改进的Glauber理论来解释.但是,用改进光学极限和少体近似的Glauber理论却低估了27P的实验数据.理论分析表明,扩大的核芯加质子晕可能是响应27P+28Si反应截面增强的机制. The reaction cross sections of~(27,28)P and the corresponding isotones on Si target were measured at intermediate energies. The measured reaction cross sections of the N=12 and 13 isotones show an abrupt increase at Z=15. The experimental results for the isotones with Z≤14 and~(28)P can be described well by the modified Glauber theory of the optical limit approach. The enhancement of the reaction cross section for~(28)P could be explained by the modified Glauber theory with an enlarged core. Theoretical ana...     

质子入射散裂产物理论研究方法探讨

简要介绍了几种关于中高能质子入射引起散裂反应产物理论计算的方法,以及这些方法的最新发展.比较了这些方法在理论计算中的特点,指出经典外推方法有局限性,量子分子动力学方法和改进后的M C方法的计算结果与实验数据有较好的符合,但是计算量大,而且量子分子动力学方法在与宏观输运理论连接上存在不少的困难.半经验计算方法已经取得了初步的成果,需要根据新的实验结果来对其进行发展. The analysis on spallation product of proton-induced reaction with intermediate energy has important applications, such as astrophysics, biophysics, spallation neutron source, and accelerator-driven system (ADS) etc. In recent year, some theoretical models have been developed to investigate this reaction processes. At present work, we introduce the extrapolated classic theory, the quantum molecule dynamic (QMD) plus statistical decay and fission models, the method of Mento-Carlo and Smiempirical method for...     

A Complexity View of Acid Deposition

We show that acid deposition is analogous to complex systems composed of a series of interconnected components. Frequency-size distributions of weekly hydrogen deposition (WHD) of precipitation are consistent with double power-law in two different regimes separated by a crossover WHD. The distribution of variations in acid deposition over a week interval is remarkably symmetrical, with long tail extending over eight orders of magnitude. The acid deposition fluctuations exhibit fractal Brown motion with two different temporal scaling regimes and long-range correlation exists in the series. The power-laws in the acid deposition dynamics are considered to be indicators of self-organization of atmosphere under environmental pollution stress.     

镁离子内扩散铌酸锂研究(Ⅱ)—— X射线衍射和扫描电子显微镜表征

对不同扩散条件的铌酸锂单晶基片进行了X射线衍射分析(XRD)和扫描电子显微镜观察(SEM)。结果表明,在扩散表面富镁层出现一新相结构,可能是由Li-Mg-Nb-O组成的三元系相结构,这一新相被认为是镁离子内扩散的真正扩散源。并对晶格发生畸变、镁离子内扩散机理以及镁的扩散层折射率变化机理进行了分析和讨论。 关键词：     

较低能区质子与核弹性散射相对论性的研究

在能量低于300MeV的能区中讨论了含有罗仑兹不变性的相对论性光学势.并用严格的分波方法求解含有标量势和矢量势的Dirac方程.对质子在300—65MeV能区中与⁴⁰Ca核作计算并与弹性散射微分截面dσ/dΩ,分析本领A_y(θ)和自旋转动函数Q(θ)的实验结果比较.看到改进了的相对论性光学势与这些实验值符合甚好.     

稀土区近滴线的β缓发质子衰变

简要回顾了自20世纪70年代以来实验研究稀土区β缓发质子衰变的历史. 综合报道了在过去10年内中科院近物所实验研究稀土区近滴线核的β缓发质子衰变的进展, 主要包括首次观测沿奇Z质子滴线的9种新核素的β缓发质子衰变以及rp-过程中两种等待点核的衰变新数据, 并将这些结果与不同的核模型理论计算进行了比较和讨论. 最后对今后的工作进行了初步展望.     

熵与信息——麦克斯韦妖的启示

 在生物进化论的背后,存在两个带根本性的问题:一是生命的起源,即如何从无生命的物质变为有生命的物质,也可以说从无序到有序的问题;二是生物的遗传与变异,那就是从有序到有序的问题.对于第一个问题,目前科学家掌握的资料尚少,还没有得到明确的结论;而对于第二个问题,已经画出了一个基本的轮廓,这是20世纪自然科学的最重大成就之一.     

Raman Spectra of Proton-Exchanged LiNbO3 Optical Waveguides

Based on the Raman spectrum measurement, we investigate the mechanism of proton exchange, by which the optical waveguides are formed in the LiNbO3 crystal which are proton doped. The proton source is formed by a mixture of benzoic and adipic acids. The experimental results show that there is a Raman formant peak of optical waveguide at 650cm^-1, and the higher the relative percentage of the mol ratio of adipic acid dilution, the higher the intensity of the Raman formant peak.