测灵敏电流计内阻的实验方法对比

在“灵敏电流计的特性研究”实验中,采用测量电流计内阻的传统方法“半偏法”,该方法重复测量结果存在较大误差。本文采用改进后的实验方法“变偏法”测量内阻,并用多点测量取平均的方法进行数据处理,明显减小了实验误差。     

金属薄膜制备及物性测量系列实验

介绍了由模拟真空实验和“金属薄膜的制备”、“金属薄膜厚度的测量”、“金属薄膜电阻率的测量”,以及“金属薄膜生长过程的动态监测”等4个实验组成的金属薄膜制备与物性测量系列实验.这组实验与现代科学技术发展联系紧密,仪器设备可靠,操作简单,适合于普通物理实验阶段的研究性教学.     

Z—1型毛细管粘滞系数测量仪

液体粘滞系数测定是目前各高等院校物理实验和物理化学实验等课程中的基本实验项目.最常采用的实验方法有“落球法”,“转筒法”,“毛细管法”.以上方法各有其测量的局限性、测量精度不高、调试测量困难、容易     

用NaI晶体和中子实验仪开设的实验

前言在“教学中子实验仪”中,我们把 D—D中子管用于实验教学,利用这样的中子源和最普通的测量仪器,也能开设多个实验课题。我们使用β计数器和 I_a、Rh、Ag 等激活片,给学生开设了“人工放射性核素半衰期的测量”、“热中子通量的测量”、“热中子在聚乙烯介面上的反射系数的测量”等实验。用 NaI(T1)闪烁谱仪开设了“氘结合能的测量”、“热中子感生~(128)Ⅰ放射性的生长和衰变规律的测量”,还准备增设“~(128)Ⅰ     

锰铜压力计在测量中的接地问题

 锰铜压力计是冲击波物理实验研究中重要的传感器之一。对锰铜压力计在冲击压力测量中的“接地”问题进行了分析和讨论。分析和实验表明，不正确的“接地”会给冲击压力测量带来较大的偏差，甚至得到畸变的测量结果。     

“神龙一号”新型束位置探测器研究

介绍了钮扣电极的应用原理, 并且在原理上与电阻环探测器作了比较, 分析了 这两种探测器各自的优缺点. 根据原理实验的结果, 重新设计了钮扣电极测量 装置. 对原测量盘结构上不合理的地方进行了改进, 并且在新设计中考虑 了“神龙一号”加速器的高真空密封. 在“神龙一号”的强流束实验中, 钮扣电极如实地反映了束流的波形以及束心的偏移量, 其束位置曲线与电阻环曲线 基本吻合, 亦证明了钮扣电极的测量数据是可信的. 在实验中钮扣电极的测量 不确定度达到0.5mm, 满足“神龙一号”强流束实验的测量需要.     

静电场描绘实验仿真研究

虚拟仿真已成为大学物理实验教学中的重要技术手段，为加强静电场理论实验效果的认知，基于MATLAB App Designer开发了静电场描绘实验仿真软件，通过有限差分法得到数值解，利用MATLAB编写用户界面，实现了“同轴电缆”“平行直线电极”“聚焦电极”“劈尖电极”和“平行板电极”共5个电场测量的描绘，具有调节输入电压、测量等势点、描绘等势线与电场线等多项功能，并可将实验测量结果、解析公式与仿真结果进行对比.静电场描绘实验仿真软件的开发，有助于形象地认识静电场和建立完整的电场分析思维体系。     

第53届国际物理奥林匹克竞赛实验试题介绍及解答

第53届国际物理奥林匹克竞赛的2道实验试题为“质量测量”和“利用双折射测量厚度”.“质量测量”题目借鉴了基布尔秤的基本思想,涉及胡克定律、安培力、电磁感应定律和弹簧振子共振方面的知识,考查选手的基本测量、数据处理(如曲线改直)、作图和不确定度评定方面的能力;“利用双折射测量厚度”题目要求自行搭建类似分光计的装置,借助光栅衍射进行光谱测量,并结合偏振光干涉来测量双折射材料的厚度,题目对仪器调节的要求比较高,测量数据量也比较大.本文主要介绍实验试题和参考答案.     

“空气比热容比”教学中的物理思想与测定的关键问题分析

该实验从诸多气体状态变化中选取了3个关键的状态,实验设计巧妙,整个实验中涉及的理论分析过程复杂,实验操作有很多不可控因素,因此如何在实验教学中把握实验的设计思想,找到测量的关键点显得尤为重要.本文旨在分析实验过程的基础上,利用力学中“回复力”的概念,使学生快速掌握实验过程的变化规律,并以“压强”为控制因素,进行数据记录,从而使学生把握了实验测量的关键点,提高了实验的教学效率.     

一种改进型源倍增法的模拟研究与验证

针对源倍增法测量次临界度受到基波份额变化以及通量畸变影响的问题，有文献提出使用环形“集总”探测器布置和“刻度曲线”来改善其测量结果的方法。为了验证该方法的实用性，用超级蒙特卡罗核模拟软件系统SuperMC与混合评价数据库HENDL，以日本京都大学KUCA铅基实验装置为对象, 展开了模拟研究。研究结果表明:该改进方法在KUCA实验装置上是适用的，说明此改进方法具有较好的工程应用潜力。模拟结果表明，使用KUCA装置中现有的六个裂变室进行“集总”探测可以给出相对准确的“测量”次临界度，但为了使测量结果更加准确，在未来实验中，可以在堆芯外围布置更多对称的探测器进行“集总”探测。     

Theoretical calculation of the isoelectronic line ratio of Li-like Ti and Cr under different mixture ratios

With the consideration of coronal conditions, a simplified model and the steady-state rate-equation are used to calculate the isoelectronic line ratio for transition in Li-like Ti and Cr from the electron temperature 400 to . The relation between the isoelectronic line ratio and the electron temperature are provided under different mixture ratios of Ti and Cr. Then, the mixture ratio from 2:1 to 3:1 between Ti and Cr are obtained that are suitable for the electron temperature diagnostic by using isoelectronic line ratio of Li-like Ti and Cr. The relative abundance of two close ionization stages, which is from bare nucleus to Be-like ionization stage, are given and show that the He-, Li- and Be-like are the principal ionization stages from 400 to for Ti and from 500 to for Cr. The Li-like charge state will reach the maximum distribution approximately from 400 to for Ti and from 547 to for Cr. The paper also shows that the dielectronic recombination and spontaneous radiative recombination rates only have small effects on the isoelectronic line ratio in the electron temperature 400-.     

Gravity as Archimedes’ Thrust and a Bifurcation in that Theory

Eulers interpretation of Newtons gravity (NG) as Archimedes thrust in a fluid ether is presented in some detail. Then a semi-heuristic mechanism for gravity, close to Eulers, is recalled and compared with the latter. None of these two gravitational ethers can obey classical mechanics. This is logical since the ether defines the very reference frame, in which mechanics is defined. This concept is used to build a scalar theory of gravity: NG corresponds to an incompressible ether, a compressible ether leads to gravitational waves. In the Lorentz–Poincaré version, special relativity is compatible with the ether, but, with the heterogeneous ether of gravity, it applies only locally. A correspondence between metrical effects of uniform motion and gravitation is assumed, yet in two possible versions (one is new). Dynamics is based on a (non-trivial) extension of Newtons second law. The observational status for the theory with the older version of the correspondence is summarized.     

“黑青”“黑碧”的谱学鉴别特征探究

“黑青”指颜色近黑色,主要成分为透闪石的青玉。“黑碧”指颜色近黑色,主要成分为阳起石的碧玉。采用电子探针、激光剥蚀电感耦合等离子体质谱仪和红外光谱测试分析手段,确定“黑青”“黑碧”的矿物种属。采用拉曼光谱、显微紫外-可见分光光度计、红外光谱对“黑青”“黑碧”的谱学鉴别特征进行探究。“黑青”为标准透闪石拉曼谱峰,“黑碧”的谱峰位置与“黑青”存在几个波数的偏差,向波数小的方向移动。可见-近红外波段,“黑青”出现445 nm吸收峰,680和940 nm宽吸收带,为Fe2+和Fe3+作用;“黑碧”出现445 nm吸收峰,660和690 nm双吸收峰以及970 nm吸收峰,为Fe2+,Fe3+,Cr3+作用。显微紫外-可见光谱可分析到样品的近红外区,“黑青”在1 397,2 310,2 387和2 466 nm出现强吸收峰,1 915和2 120 nm出现弱吸收峰;“黑碧”在1 400,2 313和2 394 nm出现吸收峰。红外光谱分析“黑青”在5 225,4 738,4 692,5 349,4 317,4 190和4 064 cm-1存在吸收峰;“黑碧”在4 708,4 307,4 178和4 031 cm-1存在吸收峰。显微紫外-可见光谱与红外光谱分析结果虽然存在小的差异,但基本保持一致,以红外光谱分析结果为准。将透闪石质的“黑青”、阳起石质的“黑碧”、广西大化阳起石质玉进行对比,综合红外光谱和显微紫外-可见光谱分析结果得出“黑青”（透闪石）与“黑碧”（阳起石）近红外光谱的鉴别特征：“黑青”（透闪石）在4 800～4 600 cm-1存在两个吸收峰,4 350～4 300 cm-1存在分裂双吸收峰;“黑碧”（阳起石）在4 800～4 600 cm-1存在一个弱吸收峰,4 350～4 300 cm-1存在一个吸收单峰。且“黑碧”（阳起石）的近红外吸收峰相较于“黑青”（透闪石）整体向低波数方向移动。     

Anti-photon

It should be apparent from the title of this article that the author does not like the use of the word photon, which dates from 1926. In his view, there is no such thing as a photon. Only a comedy of errors and historical accidents led to its popularity among physicists and optical scientists. I admit that the word is short and convenient. Its use is also habit forming. Similarly, one might find it convenient to speak of the aether or vacuum to stand for empty space, even if no such thing existed. There are very good substitute words for photon, (e.g., radiation or light), and for photonics (e.g., optics or quantum optics). Similar objections are possible to use of the word phonon, which dates from 1932. Objects like electrons, neutrinos of finite rest mass, or helium atoms can, under suitable conditions, be considered to be particles, since their theories then have viable non-relativistic and non-quantum limits. This paper outlines the main features of the quantum theory of radiation and indicates how they can be used to treat problems in quantum optics.It is a pleasure to join in the 60th birthday celebration of the Director, Herbert Walther, of the Max-Planck-Institute for Quantum Optics at Garching, and wish him much happiness and many more years of his very great scientific creativity.     

Heterogeneous Chemiluminescence of Crystal Phosphors on X‐Ray or UV Irradiation

Using a highvacuum assembly with molecular beams and setups with an implemented atom probe, we investigated atomic and molecular adsorption luminescence of the oxides CaOBi and MgO in O and O₂ beams and also radicalrecombination luminescence excited by H and O atoms in ZnS and in ZnS,CdS samples activated with silver, copper, and the rareearth element Tm. It is established that exposure to UV light and xray radiation of the CaOBi, MgO, and ZnSTm samples, where the mechanism of direct excitation of heterogeneous chemiluminescence (HCL) is realized, does not influence the characteristics of the heterogeneous chemiluminescence, whereas similar exposure of the ZnS,CdSCu,Al and ZnS,CdSAg samples and of selfactivated ZnS, in which the excitation of heterogeneous chemiluminescence is due to the ionization of the lattice, leads to an increase in the intensity of heterogeneous chemiluminescence up to five orders of magnitude. The mechanisms of the phenomenon are considered.     

In search of dark horses: Affinity maturation of phage-displayed ligands

Summary Most combinatorial libraries are sparse in that only a tiny fraction of the relevant class of compounds is represented. This sparseness can be compensated in some measure by alternating rounds of selection with rounds of mutagenesis. Thus, clones are selected from the initial library by some criterion of fitness, such as affinity for a particular receptor. The selected clones are then mutagenized to generate a mutant library, which serves as input to the next round of selection, and so on. If the first round of selection is too stringent, rejecting all but the very fittest clone in the initial library (the initial champion), we might miss dark horses; clones in the initial library that are inferior to the initial champion, yet can be mutated to even higher fitness than can that champion. A more thoughtful strategy is to alternate nonstringent selection with simultaneous mutagenesis of many selected clones en masse.     

The Photophysics of β-Tyrosine and Its Simple Derivatives

Synthesis and photophysical studies of (O-methyl)--tyrosine (-tyrosine; an analogue of tyrosine, in which the amino group is moved from the - to the -carbon, closer to the phenol ring) and its derivatives with a blocked amino and/or carboxyl group were performed to explain the nature of the fluorescence of tyrosine derived analogues. All -tyrosine derivatives, except Ac-Tyr(Me), displayed the monoexponential fluorescence decay. The biexponential fluorescence decay observed for Ac-Tyr(Me) is assumed to be the result of the presence of two low-energy conformations (extended and with an intramolecular hydrogen bond). Higher quenching of the fluorescence of -tyrosine derivatives by the N-acetyl group than by the N-methylamide group moved farther was found, contrary to the data found for the respective derivatives of natural tyrosine. The obtained photophysical data are discussed with theoretical calculations (AMBER, AM1) on the basis of the rotamer model.