Search

Intense laser–plasma interactions produce high brightness beams of gamma rays, neutrons and ions and have the potential to deliver accelerating gradients more than 1000 times higher than conventional accelerator technology, and on a tabletop scale. This paper demonstrates one of the exciting applications of this technology, namely for transmutation studies of long-lived radioactive waste. We report the laser-driven photo-transmutation of long-lived 129 I with a half-life of 15.7 million years to 128 I with a half-life of 25 min. In addition, an integrated cross-section of 97±40 mbarns for the reaction 129 I(γ ,n) 128 I is determined from the measured ratio of the (γ ,n) induced 128 I and 126 I activities. The potential for affordable, easy to shield, tabletop laser technology for nuclear transmutation studies is highlighted.

tau-Ag{sub 1/2}Cu{sub 1/2}V{sub 2}O{sub 5} compound crystallises in the monoclinic system space group C2/m with cell parameters a=11.757(4) A, b=3.6942(5) A, c=9.463(2) A, and beta=114.62(2){sup o}. The structure is build up with V{sub 4}O{sub 10} D4 double layer. The silver and copper ions are located in two different oxygenated tunnels. Examination of electronic density maps shows that while the silver ions are located in defined crystallographic sites, the copper ones are fully delocalised over the whole tunnel. Comparison with delta-Ag{sub x}V{sub 2}O{sub 5} and epsilon-Cu{sub x}V{sub 2}O{sub 5} refined structure allows to define crystal chemistry parameters governing the ionic delocalisation and give clues to predict from structural consideration the expected electrical behaviour with the aim to make possible a structural design to enhance guest species reactivity. - Graphical abstract: The role of nature and amount of guest species on their respective localisation Evidence for full delocalisation of copper ions and diffusion pathways visualisation Display Omitted

Single crystals of diantimony molybdenum hexaoxide have been grown by solid-state reaction. This oxide crystallizes as a layered structure, as in the case of the previously reported Sb 2 WO 6 . Mo atoms are located in severely distorted O-atom octahedra while each Sb atom is bonded to five O atoms, three at short distances and two at longer distances, retaining the three-dimensional array.

Nuclear Security aims at the prevention and detection of and response to, theft, sabotage, unauthorized access, illegal transfer or other malicious acts involving nuclear material". Nuclear Forensics is a key element of nuclear security. Nuclear Forensics is defined as a methodology that aims at re-establishing the history of nuclear material of unknown origin. It is based on indicators that arise from known relationships between material characteristics and process history. Thus, nuclear forensics analysis includes the characterization of the material and correlation with production history. To this end, we can make use of parameters such as the isotopic composition of the nuclear material and accompanying elements, chemical impurities, macroscopic appearance and microstructure of the material. In the present paper, we discuss the opportunities for attribution of nuclear material offered by nuclear forensics as well as its limitations. Particular attention will be given to the role of nuclear reactions. Such reactions include the radioactive decay of the nuclear material, but also reactions with neutrons. When uranium (of natural composition) is exposed to neutrons, plutonium is formed, as well as 236U. We will illustrate the methodology using the example of a piece of uranium metal that dates back to the German nuclear program in the 1940's. A combination of different analytical techniques and model calculations enables a nuclear forensics interpretation, thus correlating the material characteristics with the production history., JRC.E.8-Nuclear Safeguards and Forensics

High-energy electrons can be produced in interactions of intense, ultra-short laser pulses with plasmas. Experiments conducted in the regime of moderate laser power (a few terawatts [TW]) are attracting increasing attention for their possibility of optimizing the acceleration process. Here we report the successful production of several-MeV electron bunches in interactions of femtosecond laser pulses from a 10 TW tabletop laser with supersonic gas-jets. The laser–plasma interaction and the obtained electron bunches have been characterized in detail, and conditions for stable and reproducible acceleration have been found. The accelerated electron bunches have been characterized by means of the measurement of the induced photo-activation of a gold sample via bremsstrahlung-generation of photons with suitable energy. The obtained result opens up a wide range of possible applications of the compact electron source for the concerns of nuclear physics studies. Some of them are briefly considered in this paper.

NUCLEONICA is a new nuclear science web portal from the European Commission's Joint Research Centre. The portal provides a customisable, integrated environment and collaboration platform for the nuclear sciences using the latest internet "Web 2.0" dynamic technology. NUCLEONICA is aimed at professionals, academics and students working with radionuclides in fields as diverse as the life sciences (e.g., biology, medicine, agriculture), the earth sciences (geology, meteorology, environmental science) and the more traditional disciplines such as nuclear power, health physics and radiation protection, nuclear and radio-chemistry, and astrophysics. It is also used as a knowledge management tool to preserve nuclear knowledge built up over many decades by creating modern web-based versions of so-called legacy computer codes., JRC.E.4-Nuclear fuels

A gamma-ray source with an intense component around the giant dipole resonance for photonuclear absorption has been obtained via bremsstrahlung of electron bunches driven by a 10-TW tabletop laser. 3D particle-in-cell simulation proves the achievement of a nonlinear regime leading to efficient acceleration of several sequential electron bunches per each laser pulse. The rate of the gamma-ray yield in the giant dipole resonance region (8

A beam of MeV protons, accelerated by ultraintense laser-pulse interactions with a thin target foil, is used to investigate nuclear reactions of interest for spallation physics. The laser-generated proton beam is shown (protons were measured) to have a broad energy distribution, which closely resembles the expected energy spectrum of evaporative protons (below 50 MeV) produced in GeV-proton-induced spallation reactions. The protons are used to quantify the distribution of residual radioisotopes produced in a representative spallation target (Pb), and the results are compared with calculated predictions based on spectra modeled with nuclear Monte Carlo codes. Laser-plasma particle accelerators are shown to provide data relevant to the design and development of accelerator driven systems. © 2005 The American Physical Society.

International audience; This study deals with the enzymatic modification of vegetable oils with the help of a newreactor design. Basically, the newreactor is a porous membrane contactor along and through which substrates are flowing. It is constituted from an enzymatic membrane and uses supercritical carbon dioxide (SC CO2) to fluidify the highly viscous substrates. The interesterification between castor oil triglycerides and methyl oleate catalysed by a lipase was chosen as a model reaction. It was preliminary tested and characterized in a batch reactor. Then the feasibility of the new process was demonstrated on a cross-flow filtration unit operating under SC CO2 conditions. The stability of the immobilized enzymes was checked and the influence of the transmembrane pressure on the reaction rate was observed.

Neutron production capabilities of table-top laser accelerated protons based on data from a high-energy single-shot large laser are addressed. Recently, McKenna et al (2005 Phys. Rev. Lett. 94 084801) have analysed the energy spectrum for a beam of protons accelerated on the VULCAN laser. In this paper, we present a new analysis of the same experiment which demonstrates, for the first time, production levels in excess of 109 neutrons per laser shot within a nanosecond pulse through (p,xn) reactions on lead targets. We have used this natPb(p,xn) conversion analysis approach to make predictions on the neutron production capabilities of table-top laser systems. Neutron spectra for current state-of-the-art table-top lasers have been calculated, and we have estimated that current systems are capable of producing 106 neutrons per second in nanosecond pulses. Furthermore, we have found that nanosecond neutron pulses at a rate of 5 × 109 neutrons per second are possible with the next generation of table-top lasers currently under construction., JRC.E.4-Nuclear fuels

An interactive multimedia tool, Nuclides.net, has been developed at the Institute for Transuranium Elements. The Nuclides.net "integrated environment" is a suite of computer programs ranging from a powerful user-friendly interface, which allows the user to navigate the nuclides chart and explore the properties of nuclides, to various computational modules for decay calculations, dosimetry and shielding calculations, etc. The product is particularly suitable for environmental radioprotection and radioecology. Detailed descriptions of Nuclides.net and some potential applications in radioprotection and radioecology are presented.

Other chapters in this book are concerned with the mechanism of cure of cyanate esters (CE), kinetics, processing and the structure-properties relationships. However, all these results mainly concern pure cyanates. The major uses of these polymers are in the electronics industry (printed circuitboards) and in the aerospace industry with a market of 70 and 30%, respectively [1].

In the last decade an evolution of experimental relativistic laser-plasma physics has led to highly sophisticated lasers, which are now able to generate ultra short pulses and can be focused to intensities in excess of 10(21) W cm(-2), with more than 500 J on target. In the intense electric field of the laser focus, plasma with temperatures greater than 10 billion degrees can be generated. The laser interactions with solid or gas targets can generate collimated beams of highly energetic electrons and ions. Experiments utilizing high-intensity laser systems turn out to be an interesting and versatile source for radiation, high-energy particles and nuclear reactions, without recourse to large-scale facilities such as nuclear reactors or particle accelerators. The possibility of accelerating electrons to energies over 200 MeV in such early experiments led to the utilization of high-energy bremsstrahlung radiation in order to investigate laser-induced gamma reactions. Many experiments of this type have been reported in several laboratories worldwide. However, to our knowledge, no dedicated investigations have been reported with respect to the characterization of the generated bremsstrahlung in such experiments. As it is not experimentally feasible to measure directly a bremsstrahlung spectrum, we report in the present paper on a dedicated series of calculations on the generated bremsstrahlung distributions from two experimental electron spectra measured using the giant pulse VULCAN laser and a gas jet target. Potential applications are also investigated.

International audience; Two new compounds In2VO5 and In2TiO5, were prepared by solid-state reactions. In2VO5 crystallized as black needles with the a 7.232, b 3.468 c 14.82 Å, space-group Pnma, and Z = 4. In2TiO5 is isostructural (a 7.237, b 3.429, c 14.86 Å). The structure, determined by x-ray single-crystal anal. using a crystal of In2VO5, was deduced from the Patterson function and refined by 3-dimensional Fourier and least-squares methods to an R value of 0.046. The 2 independent In ions are both in trigonal antiprisms flattened along a 3-fold axis; these polyhedra unite by edge-sharing into groups of 4 forming infinite ribbons in the direction of the short b axis. The ribbons (In2O4)n2n- are held together by the V ions which are 5-coordinated, with the 3 oxygens belonging to the ribbons and the 2 extra oxygens at the corners of a trigonal bipyramid. The relationships to the La2TiO5 and Y2TiO5 structure types are discussed.

Low pressure sublimation of tri-2,2′-bipyridinesilicon(0) leads to di-2,2′-bipyridinesilicon crystals. The unit cell is orthorhombic, space group Pbca, a 21.509, b 15.995, c 10.127 », Z = 8. The crystal structure was solved using 490 reflexions recorded at room temperature and refined down to a reliability index R = 0.046. The silicon atom is surrounded tetrahedrally by the bidentate 2,2′-bipyridine ligand with a mean NSiN angle of 100° and a mean SiN bond length of 1.72 ».

In this paper a new approach is suggested which enables one to avoid singularities in the goal coordination method for systems with state variable coupling. This makes the method of practical utility for the control of large dynamical systems. The new approach has the additional advantage of reducing the subproblem computations considerably. The method is illustrated on two classical examples, one which is linear and the other, non-linear.

Galy-Carles J. La production et le commerce des Oranges dans le monde.. In: Revue de botanique appliquée et d'agriculture coloniale, 10ᵉ année, bulletin n°112, décembre 1930. pp. 928-953.

Galy-Carles J. La culture du Théier en Russie. In: Revue de botanique appliquée et d'agriculture coloniale, 8ᵉ année, bulletin n°86, octobre 1928. pp. 683-692.

In ArXe mixtures, spectroscopic studies of the far UV emissions have shown the presence of large excitation energy transfers from argon to xenon. The argon continuums decrease rapidly giving way to molecular and atomic Xe emissions as small quantities of Xe are added to the Ar. The spectra of mixtures containing just a few percent Xe are similar to spectra of pure xenon. Kinetic analysis of the argon continuum at 127 nm shows that energy transfers occur not only from the Ar2* (3[MATH]+u) molecular states which give rise to the second argon continuum (k1 = 1.5.107 torr-1 s-1) but also from the atomic precursors of Ar2 * (k2 = 2.5.107 torr-1. s-1). The cross sections of both processes are very high.

The results obtained in a multiphotonic excitation of xenon near the 6s'|1/2|1 state by a tunable pulsed dye laser are presented. At low pressure the lP1 resonnant state of xenon is created by 3-photon resonnant absorption. When the pressure increases, the excitation spectra widen and shift towards shorter wavelengths. We explain this phenomenon by an excitation of the Xe2 molecules in the ground state O+g towards molecular excited state 1u(1P 1 correlated to 1P1 state. A spectral analysis showed the presence in the luminescence of the first and second continuum of xenon. We demonstrated that the third-harmonic generation of the incident laser beam intervenes in the excitation process. This radiation was detected and his pressure dependance studied. The phase matching parameter cXe and the nonlinear susceptibility were measured.

Galy-Carles J. Etat actuel de la culture du Cotonnier au Soudan Anglo-Egyptien. Observations de M. V.-H. Himbury.. In: Revue de botanique appliquee et d'agriculture coloniale, 13ᵉ annee, bulletin n°137, janvier 1933. pp. 46-50.

We report on a laboratory EXAFS spectrometer optimized for transmission dispersive mode. Absorption edges ranging from 6 to 20 keV can be studied. Factors determining energy range and resolution are detailed. A new asymmetric geometry which allows to use all the lattice planes of the dispersing crystal is described and the choice of the best plane analysed. EXAFS spectra of Cu metal and Cu acetate, obtained on this laboratory facility, are compared to the corresponding spectra recorded on the French synchrotron facility (LURE).