1,782 research outputs found

    Effect of Beam Dynamics Processes in the Low Energy Ring ThomX

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    As part of the R\&D for the 50 MeV ThomX Compton source project, we have studied the effect of several beam dynamics processes on the evolution of the beam in the ring. The processes studied include among others Compton scattering, intrabeam scattering, coherent synchrotron radiation. We have performed extensive simulations of a full injection/extraction cycle (400000 turns). We show how each of these processes degrades the flux of photons produced and how a feedback system contributes to recovering most of the flux.Comment: Submitted to IPAC'14, WEPRO00

    On the non-paraxial modes of two-dimensional nearly concentric resonators

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    to be published in Applied OpticsA non-paraxial scalar diffraction integral is used to determine numerically the resonance modes of a two dimensional nearly concentric Fabry-Perot resonator. Numerical examples are provided and results are compared to those published by Laabs and Friberg [IEEE J. Quant. El., vol. 35, pp. 198-207, 1999]. Discrepancies are reported and further discussed on the basis of the difference between the solution space supported by the numerical method used in the present work and the one used by Laabs and Friberg

    ThomX Technical Design Report

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    Exploring the Critical Factors for Sustainable Product-service Systems Implementation and Diffusion in Developing Countries: An Analysis of two PSS Cases in Brazil

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    AbstractThis paper aims at exploring how some factors identified in the PSS and product/service innovation literature can hinder or foster sustainable PSS implementation in developing countries, since there is a lack of knowledge concerning the characteristics of PSS transition processes in different contexts. The identified factors were investigated empirically, through two PSS solutions located in an emerging economy. The main results demonstrated the role of some potential factors in supporting the implementation and diffusion of PSS solutions, especially those related to the involvement of multiple actors in the value creation and the social embeddedness. However, the role of those factors still need to be investigated in future works, since only two cases were analyzed in this research. Analyses of successful and unsuccessful PSS cases as well as the identification of other factors and characteristics of PSS implementation in different contexts are directions for further research

    Trees and water: smallholder agroforestry on irrigated lands in Northern India

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    Trees / Populus deltoids / Agroforestry / Afforestation / Reforestation / Models / Water use / Water balance / Evapotranspiration / Precipitation / Remote sensing / Irrigation requirements / India

    Whole genome sequence analysis indicates recent diversification of mammal-associated Campylobacter fetus and implicates a genetic factor associated with H2S production

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    cknowledgements We like to thank Emma Yee (U.S. Department of Agriculture) for the generation of sequence data, we thank James Bono (U.S. Department of Agriculture) for the generation of PacBio RS reads and thank Dr. Brian Brooks and Dr. John Devenish (Canadian Food Inspection Agency) for providing C. fetus strains and for critical review of this manuscript. Funding Publication charges for this article have been funded by Utrecht University, the Netherlands.Peer reviewedPublisher PD

    Linear scaling between momentum and spin scattering in graphene

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    Spin transport in graphene carries the potential of a long spin diffusion length at room temperature. However, extrinsic relaxation processes limit the current experimental values to 1-2 um. We present Hanle spin precession measurements in gated lateral spin valve devices in the low to high (up to 10^13 cm^-2) carrier density range of graphene. A linear scaling between the spin diffusion length and the diffusion coefficient is observed. We measure nearly identical spin- and charge diffusion coefficients indicating that electron-electron interactions are relatively weak and transport is limited by impurity potential scattering. When extrapolated to the maximum carrier mobilities of 2x10^5 cm^2/Vs, our results predict that a considerable increase in the spin diffusion length should be possible

    Effect of Compton Scattering on the Electron Beam Dynamics at the ATF Damping Ring

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    Compton scattering provides one of the most promising scheme to obtain polarized positrons for the next generation of e−e^- -- e+e^+ colliders. Moreover it is an attractive method to produce monochromatic high energy polarized gammas for nuclear applications and X-rays for compact light sources. In this framework a four-mirror Fabry-P\'erot cavity has been installed at the Accelerator Test Facility (ATF - KEK, Tsukuba, Japan) and is used to produce an intense flux of polarized gamma rays by Compton scattering \cite{ipac-mightylaser}. For electrons at the ATF energy (1.28 GeV) Compton scattering may result in a shorter lifetime due to the limited bucket acceptance. We have implemented the effect of Compton scattering on a 2D tracking code with a Monte-Carlo method. This code has been used to study the longitudinal dynamics of the electron beam at the ATF damping ring, in particular the evolution of the energy spread and the bunch length under Compton scattering. The results obtained are presented and discussed. Possible methods to observe the effect of Compton scattering on the ATF beam are proposed

    Do Spin-Offs Make the Academics’ Heads Spin?: The Impacts of Spin-Off Companies on Their Parent Research Organisation

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    As public research organisations are increasingly driven by their national and regional governments to engage in knowledge transfer, they have started to support the creation of companies. These research based spin-off companies (RBSOs) often keep contacts with the research institutes they originate from. In this paper we present the results of a study of four research institutes within two universities and two non-university public research organisations (PROs) in the Netherlands. We show that research organisations have distinct motivations to support the creation of spin-off companies. In terms of resources RBSOs contribute, mostly in a modest way, to research activities by providing information, equipment and monetary resources. In particular, RBSOs are helpful for researchers competing for research grants that demand participation of industry. Furthermore, RBSOs may be seen as a proactive response by Dutch public research organisations to demands of economic relevance from their institutional environment. RBSOs enhance the prestige of their parent organisations and create legitimacy for public funds invested in PROs. At the same time, most RBSOs do not have a significant impact on the direction of the research conducted at the PROs
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