Ultracold Gases and Quantum Information: Lecture Notes of the Les Houches Summer School in Singapore,edited by C. Miniatura,L-C. Kwek,M. Ducloy,B. Grémaud,B-G. Englert,L.F. Cugliandolo,A. Ekert and K. K. Phua

Measurements of the Faraday magneto-optical effect and of optical absorption in magnetic garnet crystals and films are reviewed. Earlier work was restricted to measurements in the visible spectrum; these measurements showed that the transparency was sufficient to allow magnetic domains to be studied in relatively thick slabs. Within the last year or so interest has been renewed in extending magneto-optical measurements beyond the visible spectrum. In particular, extremely low absorptions are found in the wavelength range of approximately 1–5 microns. Thie work is, in no small way, spurred by the possibility of developing a light-beam modulator using the Faraday effect in this wavelength range. Recent measurements at very short wavelengths using garnet films are also reported. By extending the short wavelength measurements to 3000 Å, about two orders of magnitude increase in Fareday rotation and optical absorption are observed, compared with the visible spectrum measurements.

The Faraday effect has been used to measure magnetic hysteresis loops in single-crystal garnet slabs. Magneto-optical observation of the corresponding domain structures shows them to be particularly simple. Detailed correlation of domain structure and hysteresis loops is described; in addition, an estimate of the domain wall energy and its width is made from these measurements.

The garnets referred to in this review are yttrium iron garnet (YIG), gadolinium iron garnet (GdIG), and YIG doped with gallium (YGaIG).     

Thickness Effect on Kβ/Kα Intensity Ratios in Barium,Lanthanum, Samarium,Gadolinium, Dysprosium,and Holmium

INTRODUCTION

Knowing the K_β/K_α intensity ratio is of great practical importance in the analysis of X-ray spectra. The information is needed in the experimental investigations of various phenomena in the fields of atomic, nuclear and radiation physics and non-destructive testing of materials and elemental analysis using X-ray fluorescence techniques. K_α, X-ray arise from transition from the L shell to K shell and K_β, X-ray arise from transition from the M, N, 0 shells to K shell.     

科学帅才K.T.康普顿

K．T．康普顿是美国著名物理学家，1908年从伍斯特学院毕业，次年在该校获得硕士学位，1912年在普林斯顿大学获得博士学位，他曾在1930—1948年间担任美国麻省理工学院校长，在该校大力推行改革，将基础科学研究引入工程教育，使该校的面貌为之一新，他也曾担任美国多项国家科学机构的要职，为美国的科学研究、军事科学研究和科学管理做出重大贡献。     

Comment on “Foam imbibition in microgravity. An experimental study” by H. Caps,H. Decauwer,M.-L. Chevalier,G. Soyez,M. Ausloos and N. Vandewalle

In a recent paper, [1] described parabolic flight experiments showing the movement of liquid into the foam during the microgravity phase. In this comment, we present a detailed theory of this process, supported by numerical calculations, confirming their conclusion that the wetting front moves with the square root of time. We further show that this diffusion process is similar for different surfactant systems, which allows us to provide bounds on the value of the diffusion coefficient.Received: 28 April 2004, Published online: 3 August 2004PACS: 82.70.Rr Aerosols and foams - 83.80.Iz Emulsions and foams     

Dynamical Processes on Complex Networks,by A. Barrat,M. Barthélemy and A. Vespignani

The present state of theory and experiment on the gravity-induced electric field in metallic conductors and the electric field in accelerated metal conductors is reviewed. The relevant equations are derived in very simple approximations. The results depend on whether the deformation of the lattice of positive ions is neglected or is taken into account. Experimental results obtained with freely falling electrons in a cavity in the metal do not agree with the measurements of potentials on rapidly spinning metal rotors. Older direct measurements of the specific charge of carriers in metallic conductors are also mentioned.     

Determination of Chemical Effect on the Kβ1/Kα, Kβ2/Kα, Kβ2/Kβ1 and Kβ/Kα X-Ray Intensity Ratios of 4d Transition Metals

It is clear that detailed studies performed under identical experimental conditions are desirable to determine the effect of the chemical environment on the value of intensity ratios. To better understand this effect, we conducted measurements on Kβ₁/Kα, Kβ₂/Kα, Kβ₂/Kβ₁ and Kβ/Kα x-ray intensity ratios. The Kα and Kβ_1,2 emission spectra for compounds of 4d transition metals Y, Zr, Nb, and Mo were measured using a Si(Li) solid-state detector. The samples were excited by 22.69 keV x-rays emitted from a ¹⁰⁹Cd radioisotopes source. The experimental results for pure elements are compared with the other experimental and theoretical values.     

Influence of Chemical Effect on the Kβ/Kα Intensity Ratios and KβEnergy Shift of Co, Ni, Cu, and Zn Complexes

报导了钴、镍、铜、锌络合物中的化学效应对Kβ/Kα强度比和Kβ能量位移的影响. 实验样品用241Am环状放射源发出的能量为59.5 keV的γ射线激发. 对样品发射的K段X射线进行检测的检测器在5.9 keV处的分辨率为150 eV. 观察了不同配体对钴、镍、铜、锌络合物的Kβ/Kα强度比和Kβ能量转移的影响,并试图解释这些配体的性质对中心原子产生的化学效应. 对实验得到的Kβ/Kα强度比数据,理论计算获得的Kβ/Kα强度比数据及其它实验得到的纯钴、镍、铜、锌的Kβ/Kα强度比数据进行了比较.     

Commentary on “Mechanical properties of monodomain side-chain nematic elastomers” by P. Martinoty,P. Stein,H. Finkelmann,H. Pleiner and H.R. Brand

We discuss the background to static and dynamic soft elasticity. The evidence in the static case and the symmetry basis for soft and semi-soft elasticity is well understood. By contrast the dynamic analogy is less clear. Lack of clean time scale separation clouds the interpretation of director relaxation keeping up, or not, with imposed strains. However, the reduction in modulus between geometries obtaining at low frequencies and being lost at high frequencies confirms that director reaction indeed determines dynamical semi-softness.Received: 13 April 2004, Published online: 17 August 2004PACS: 83.80.Va Elastomeric polymers - 61.30.-v Liquid crystals - 83.60.Bc Linear viscoelasticity