Starting from next year the technical feasibility of a direct seeding scheme at 30 and 13 nm will be studied at the Free-electron LASer in Hamburg (FLASH). During a major shutdown the SASE-FEL facility will be upgraded and it is planned to install in addition a high-harmonic generation (HHG) seed laser, a new chain of 10 m variable gap un-dulators and a dedicated commissioning beamline for photon

The quasi-stationary state characterizing the saturation of a single-pass free-electron laser is governed by the Vlasov equation obtained by performing the continuum limit of the Colson-Bonifacio model. By means of a statistical treatment, this approach allows to predict analytically the saturated laser intensity as well as the final electron-beam energy distribution. In this paper we consider the

The optical klystron installed on the Elettra storage-ring is normally used as interaction region for an oscillator free-electron laser, but, removing the optical cavity and using an external seed laser, one obtains an effective scheme for single-pass harmonic generation. In this configuration the high-power external laser is synchronized with the electron beam entering the first undulator of the

UV absorption from carbon nanoparticles is a very interesting astrophysical topic. The prominent hump centred at 217.5 nm is the most dominant feature in the interstellar extinction curve and also the most controversial and a long-standing problem in astrophysics. At the University of Milano an experimental set-up based on a Pulsed Microplasma Cluster Source has been developed for the investigatio

In a Storage-Ring Free-Electron Laser (SRFEL) giant pulses can be produced by the interaction between the light stored in the optical cavity and an electron beam with low energy-spread (cold beam). This interplay produces the heating of the beam. After the generation of a single giant pulse the overlap between electrons and radiation is periodically prevented for a time necessary to dump the energ

In a storage-ring free-electron laser (FEL), the onset and growth of intra-cavity power at the resonator wavelength can be naturally accompanied by coherent emission at higher harmonics. Contrary to what happens in singlepass linac-based devices, the electron beam is re-circulated in the storage ring and, while the microbunching becomes "thermalized" from turn to turn, the evolution of other bunch

Single-pass free-electron lasers constitute an example of systems with long-range interactions. The light-particle interplay leading to the power growth and successive relaxation towards a quasi-stationary state is governed by the Vlasov equation. A maximum entropy principle inspired to Lynden-Bell's theory of "violent relaxation" for the Vlasov equation can be invoked to analytically characterize

In vivo dosimetry of IMRT from Copenhagen University Hospital

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98 procent av all forskning och utveckling sker utanför Sverige. Bästa vägen till högre välstånd bygger på strategin att vi måste bli väsentligt bättre på att hitta innovationer, var i världen de än finns. Det är viktigare än att tro att nya high-techföretag ska fixa allt, skriver Johan Schlasberg, vd för mobiltjänstföretaget IDmessage (IDstories).

Owing to the significant societal value of inland water resources, there is a need for cost-effective monitoring of water quality on large scales. We tested the suitability of the recently launched Sentinel-2A to monitor a key water quality parameter, coloured dissolved organic matter (CDOM), in various types of lakes in northern Sweden. Values of a(420)CDOM (CDOM absorption at 420 nm wavelength)

Pollination deficits are widespread in current agriculture, so improving management for crop pollination is critical. Here we review the two most common management approaches to enhance crop pollination, species and habitat management, by providing referenced lists of successful examples. We pinpoint that these approaches have been studied in isolation from each other, with little discussion on po

We study asymptotic properties of the following Markov system of N≥3 points in [0, 1]. At each time step, the point farthest from the current centre of mass, multiplied by a constant p>0, is removed and replaced by an independent ζ-distributed point; the problem, inspired by variants of the Bak–Sneppen model of evolution and called a p-contest, was posed in Grinfeld et al. (J Stat Phys 146, 378–40