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Geysers of Helium burst as if liquid

Geysers of Helium burst as if liquid

New experiments on the flow of solid He through a microscopic hole reveal a mechanism that triggers the geysers based on the breakdown of a plug located upstream of the source chamber.

The vacuum expansion of solid helium through a micrometric orifice was suggested as a mean to inject excess vacancies into the solid bulk [R. Grisenti et al, J. Electr. Spectr. 129 (2003) 201]. But while the He flow seems smooth, unexpected periodic bursts out of the orifice (geyser effect) are observed during these vacuum expansion experiments.

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EPJ D - New call for papers on cold quantum matter

The topics of this special issue will include: Quantum simulation using cold atoms in optical lattices; fermionic mixtures of ultracold atoms; collisions of cold polar molecules; controlled interactions in quantum gases of metastable atoms; cavity-mediated molecular cooling; quantum-degenerate dipolar gases of bialkali molecules.

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EPJ D - Gaetana Laricchia wins Thomson Medal

Gaetana Laricchia

Professor Gaetana Laricchia of UCL, London, has been awarded the Thomson medal and prize for her contributions to the development of the world's only positronium beam and its use to probe the properties of atoms and molecules. This follows closely the Occhialini prize which she received in 2009.

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EPJ C article selected Fast Breaking Paper by ScienceWatch

The physics paper with the highest percentage increase in citations so far in 2010, as determined by ScienceWatch.com, is `Parton distributions for the LHC' by A Martin et al. Eur.Phys.J.C63:189-285, 2009 This article has meanwhile been cited over 200 times, according to the reference database for high-energy physics, SPIRES. The paper was already selected as highlighted article by the editorial board of EPJ C, featuring on the cover of the September 2009 issue of this journal.

EPJ E - Bendy interfaces

Bendy interfaces

The shape of the interface between two fluids can be controlled by changing the refractive index contrast between the fluids, researcher from the Universite Bordeaux have shown. Optofluidics are methods based on the combination of optics and fluidics which have recently promoted innovative approaches to manipulate liquid interfaces. Since flows are optically driven, researchers call this emerging field optohydrodynamics. The recent paper published in EPJ E presents a fine example of optohydrodynamic actuation at the microscopic scale, based on experimental and predictive numerical results. This work illustrates one of the simplest manifestations of optohydrodynamics and provides a frame to anticipate further developments of contactless interface micromanipulation by lasers.

To read the full paper ‘Optohydrodynamics of soft fluid interfaces: Optical and viscous nonlinear effects’ by H. Chraibi et al. click here

EPJ E - Pierre-Gilles De Gennes Lecture Prize

Sam Safran

This July, during the International Soft Matter Conference 2010 in Granada, Spain, Professor Sam Safran will give the EPJ E - Pierre Gilles De Gennes lecture, associated with a prize given by the publishers of EPJ.
This is the first edition of the *EPJE - Pierre-Gilles De Gennes Lecture Prize*, which takes the name from the illustrious Nobel laureate who founded EPJ E.
The Editors in Chief elected Prof. Sam Safran of the Weizman Instutite, Israel, as the prize recipient to acknowledge his leading research in soft matter and biological physics. The prize was also endorsed by the ISMC 2010 conference committee.
The prize will be presented to Prof. Sam Safram by Prof. Dominique Langevin (who is an Associate Editor of EPJ E) at the beginning of his plenary talk, 6 July at 8.30 am.

If you wish to vist the ISMC 2010 website go to http:/ismc2010.ugr.es/

EPJ D - Speed-control zone for polar molecules

Speed-control zone for polar molecules

Stark deceleration has emerged over the last decade as a leading technique for obtaining packets of quantum-state-selected molecules whose velocity can be tuned all the way down to zero. Here, a new compact, ultrahigh-vacuum-compatible Stark decelerator is described and demonstrated. The deceleration stages are fashioned out of tantalum wires, reducing the total length to about a tenth of that of a conventional Stark decelerator with the same number of electrode pairs.

The significantly lower cost of assembling and operating the wire decelerator makes it an attractive source of cold molecules, for use in applications ranging from trapping experiments to cold collisions to sympathetic cooling.

A. Marian, H. Haak, P. Geng, and G. Meijer, Eur. Phys. J. D (2010)

Structural, optical and nanomechanical properties of (111) oriented nanocrystalline ZnTe thin films

Structural, optical and nanomechanical properties of nanocrystalline Zinc Telluride (ZnTe) films of thickness upto 10 microns deposited at room temperature on borosilicate glass substrates are reported. X-ray diffraction patterns reveal that the films were preferentially oriented along the (1 1 1) direction. The maximum refractive index of the films was 2.74 at a wavelength of 2000 nm. The optical band gap showed strong thickness dependence. The average film hardness and Young's modulus obtained from load-displacement curves and analyzed by Oliver-Pharr method were 4 and 70 GPa respectively. Hardness of (1 1 1) oriented ZnTe thin films exhibited almost 5 times higher value than bulk. The studies show clearly that the hardness increases with decreasing indentation size, for indents between 30 and 300 nm in depth indicating the existence of indentation size effect. The coefficient of friction for these films as obtained from the nanoscratch test was ~0.4.

Structural, optical and nanomechanical properties of (111) oriented nanocrystalline ZnTe thin films, M.S.R.N. Kiran, S. Kshirsagar, M.G. Krishna and S.P. Tewari (2010), Eur. Phys. J. Appl. Phys. DOI 10.1051/epjap/2010071

EPJ B - Superfluidity of a perfect quantum crystal

Only one liquid exhibits Bose-Einstein condensation in nature: Helium II, . At such temperatures, all other substances are solid. In these two papers, Vitaly Golovko demonstrates that Bose-Einstein condensation can also occur in the solid state. Moreover, it is shown that at 0 K, a condensate crystal is energetically preferable with respect to the same quantum crystal without condensate. Therefore, on lowering the temperature of the crystal there must somewhere happen Bose-Einstein condensation, as in liquid helium. This opens a huge field for experimental investigations of Bose-Einstein condensation and of its influence on properties of solids.

EPJ B - What atomistic methods tell us about the mechanical response of amorphous solids

Our understanding of elasticity, plasticity and failure in non-crystalline solids has greatly enhanced through atomic scale simulation. A new Colloquium paper In EPJ B reviews a variety of computational approaches that have been successful in elucidating the atomic scale phenomena that control the mechanics of amorphous solids. The constitutive theories that have been developed for describing mechanical response are briefly illustrated, as well as the prospects for testing the assumptions of these theories using simulation. The authors, M.L. Falk and C.E. Maloney, pose the most pressing open questions for substantiating these theoretical approaches, and ultimately for understanding and predicting the mechanical behaviour of amorphous solids.

To read the full paper "Simulating the mechanical response of amorphous solids using atomistic methods" by M.L. Falk and C.E. Maloney, European Physical Journal B click here.

Editors-in-Chief
G. Moutiers and A. Nicolas
ISSN: 2491-9292 (Electronic Edition)

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