微剂量学研究的进展

微剂量学是交叉学科的新兴领域,研究粒子在物质中能量沉积的微区分布和放射生物学效应,本文主要对微剂量学研究的进展,包括粒子的径迹结构,能量沉积和微剂量学实验技术等方面作一概述。 Microdosimetry is a rapidly developing field in the multi-disciplines. It studies energydeposition processes in media with particular interesting to living system. This paper gives short reviewon the recent progress in the study of microdosimetry including the track structure of ionzing particlesenergy deposition and new microdosimetric experimental techniques.     

HIRFL上合成的第一个新核素—208Hg

本文简述在中科院近物所HIRFL上发现的第一个新核素208Hg的合成和鉴别,兼论利用HIRFL提供的中能重离子束开展远离β稳定线核素合成和衰变研究的优势、困难以及拟采用的物理和技术路线。 The synthesis and identification of the first discovered new nuclide 208Hg on HIRFL(Heavy Ion Research Facility of Lanzhou) were described. In this paper the superiorities, difficultiesas well as the physical and technical line about the synthesis and decay study for the nuclides far fromβ-stability line to be made at HIRFL were discussed.     

考虑晶粒尺寸效应的超薄(10–50 nm) Cu电阻率模型研究

结合Marom模型与实验数据, 给出了晶粒尺寸与金属薄膜厚度的关系式. 基于已有的理论模型, 针对厚度为10–50 nm Cu薄膜, 考虑到表面散射与晶界散射以及电阻率晶粒尺寸效应, 提出一种简化电阻率解析模型. 结果表明, 在10–20 nm薄膜厚度范围内, 考虑晶粒尺寸效应后的简化模型与现有实验数据符合得更好. 相对于Lim, Wang与Marom模型, 所提模型的相对标准差分别降低74.24%, 54.85%, 78.29%. 关键词： 表面散射 晶界散射 晶粒尺寸效应 平均自由程     

Exploration of the sum of flexoelectric coef ficients of nematic liquid crystals

We present a theoretical calculation of the dependence of reflectivity Rpp of the improved fully leaky waveguide geometry,which comprises pyramid,matching fluid,and strongly anchored hybrid aligned nematic liquid crystal(NLC) cell on the internal angle.The calculation is based on the multi layer optical theory and the elastic theory of liquid crystals.For different sums of flexoelectric coefficients e11 and e33,the curve of Rpp moves a distance to the left or the right relative to the case of ignoring the flexoelectric effect and the distance of the movement varies with different flexoelectric coefficients.Consequently,the sum of flexoelectric coefficients can be explored by measuring the distance of the movement.     

Computer design of a compact cyclotron

Here we present results of the computer design of the structural elements of a compact cyclotron by the example of HITFiL cyclotron selected as the driving accelerator that is under construction at the Institute of Modern Physics (Lanzhou, China). In the article a complex approach to modeling of the compact cyclotron, including calculation of electromagnetic fields of the structural elements and beam dynamics calculations, is described. The existing design data on the axial injection, magnetic, acceleration and extraction systems of the cyclotron are used as a starting point in the simulation. Some of the upgrades of the cyclotron structural elements were proposed, which led to substantial improvement of the beam quality and transmission.     

Study on parameters influencing analytical performance of laser-induced breakdown spectroscopy

Lens-to-sample distances, delay time, atmospheric condition, laser pulse energy, etc. had obvious effects on the analytical performance of laser-induced breakdown spectroscopy. In this paper, these parameters are investigated in greater detail and we will explain how they have influences on the analytical performance. The results show that the focal plane under the sample surface can improve precision and detection limit, and the delay time should be decided according to sensitivity and accuracy. Spectral line intensity is stronger in argon than helium, nitrogen and air gas environment. Pulse energy should exceed energy threshold (about 50 mJ) which can generate plasma, and the energy should not exceed about 300 mJ to avoid plasma shielding. Under optimum parameters, concentration relative standard deviation of C, Si, Mn, P, S, Ni, and Cr for low-alloyed steel (sample number 11278) which were measured 11 times is 2.37%, 2.18%, 2.23%, 7.8%, 9.34%, 1.92%, and 2.13%, respectively. And the detection limit of C, Si, Mn, P, S, Ni, and Cr for pure steel is 0.0045%, 0.0072%, 0.0069%, 0.0027%, 0.0024%, 0.0047%, and 0.0024%, respectively.     

微波场中Josephson结的微波发射与吸收研究

采用数值仿真方法,研究微波场中约瑟夫森结微波感应台阶处的功率特性。发现微波场中约瑟夫森结不止吸收辐射,也发射辐射的情况。得到微波辐照和结电阻对功率吸收和发射的影响规律。结果表明,处于发射功率的状态对应的偏置电流范围占整个台阶总电流范围的比例可以趋于50%。这一发现对约瑟夫森结理论和应用研究具有重要的意义。     

多孔脆性介质冲击波压缩破坏的细观机理和图像

本文采用一种具有良好定量性质的离散元模型研究了带孔洞的各向同性脆性介质在细观尺度上的压缩破坏特征. 通过对孤立孔洞、三种简单的孔洞排布方式和大量孔洞随机排布等几种情况的模拟, 认识到了剪切破坏和局域拉伸破坏是冲击波压缩下多孔介质的基本破坏模式; 孔洞之间的损伤贯通会促进孔洞在较低应力下发生塌缩, 但损伤区的应力松弛过程却会对一定范围内的介质起到损伤屏蔽作用; 不同区域中损伤促进和损伤屏蔽的综合效果是在多孔脆性介质中形成一种高损伤区与低损伤区间错排布的奇特损伤分布. 本文的研究结果为深入理解脆性材料冲击波压缩破坏的演化过程和机理提供了细观尺度上的初步物理图像.     

Word diversity can accelerate consensus in naming game

In this paper, we introduce word diversity that reflects the inhomogeneity of words in a communication into the naming game. Diversity is realized by assigning a weight factor to each word. The weight is determined by three different distributions (uniform, exponential, and power-law distributions). During the communication, the probability that a word is selected from speaker's memory depends on the introduced word diversity. Interestingly, we find that the word diversity following three different distributions can remarkably promote the final convergency, which is of high importance in the self-organized system. In particular, for all the ranges of amplitude of distribution, the power-law distribution enables the fastest consensus, while uniform distribution gives the slowest consensus. We provide an explanation of this effect based on both the number of different names and the number of total names, and find that a wide spread of names induced by the segregation of words is the main promotion factor. Other quantities, including the evolution of the averaging success rate of negotiation and the scaling behavior of consensus time, are also studied. These results are helpful for better understanding the dynamics of the naming game with word diversity.     

Dual-band frequency selective surface with quasi-elliptic bandpass response

Based on the substrate integrated waveguide technology,we present a dual-band frequency selective surface(FSS) with a quasi-elliptic bandpass response.The characteristics of the quasi-elliptic bandpass response are realized by shunting two substrate integrated waveguide cavities of different sizes,with the same slots on both sides of the metal surfaces.Four cavities of different sizes and two slots of different sizes are used to design the novel FSS.Every bandpass response with sharp sidebands is induced by two transmission nulls that are generated by the coupling between the slot aperture resonance and the cavity resonance.The simulation results show that such dual-band FSS has the advantages of high selectivity and stable performance at different oblique incident angles.Moreover,it is easy to fabricate.