# OpenAccess

 2017-04-2715:21 [PUBDB-2017-02034] Journal Article et al Mitigation of the Hose Instability in Plasma-Wakefield Accelerators 17th Advanced Accelerator Concepts Workshop, AAC 2016, Meeting locationNational Harbor, Maryland, USA, 31 Jul 2016 - 5 Aug 2016 Physical review letters 118(17), 174801 (2017) [10.1103/PhysRevLett.118.174801]   Current models predict the hose instability to crucially limit the applicability of plasma-wakefield accelerators. By developing an analytical model which incorporates the evolution of the hose instability over long propagation distances, this work demonstrates that the inherent drive-beam energy loss, along with an initial beam-energy spread, detunes the betatron oscillations of beam electrons and thereby mitigates the instability. [...] OpenAccess: PDF; External link: Fulltext 2017-04-2613:10 [PUBDB-2017-01934] Book/Report/Dissertation / PhD Thesis Kärtner, F. Large-scale laser-microwave synchronization for attosecond photon science facilities [DESY-THESIS-2017-015] DESY-THESIS 134 pp., (2017) [10.3204/PUBDB-2017-01934]   Low-noise transfer of time and frequency standards over large distances provides high temporal resolution for ambitious scientific explorations such as sensitive imaging of astronomical objects using multi-telescope arrays, comparison of distant optical clocks or gravitational-wave detection using large laser interferometers. In particular, rapidly expanding photon science facilities such as X-ray free-electron lasers (FELs) and attoscience centers have the most challenging synchronization requirements of sub-fs timing precision to generate ultrashort X-ray pulses for the benefit of creating super-microscopes with sub-atomic spatiotemporal resolution. [...] OpenAccess: desy-thesis-17-015.title - PDF; PhD Thesis - PDF; 2017-04-2518:11 [PUBDB-2017-01894] Journal Article et al Pressure-induced structural change in liquid GaIn eutectic alloy Scientific reports 7(1), 1139 (2017) [10.1038/s41598-017-01233-1]   Synchrotron x-ray diffraction reveals a pressure induced crystallization at about 3.4 GPa and apolymorphic transition near 10.3 GPa when compressed a liquid GaIn eutectic alloy up to ~13 GPa atroom temperature in a diamond anvil cell. Upon decompression, the high pressure crystalline phaseremains almost unchanged until it transforms to the liquid state at around 2.3 GPa. [...] OpenAccess: PDF; 2017-04-2515:00 [PUBDB-2017-01886] Contribution to a conference proceedings et al Performance Analysis of the European XFEL SRF cavities, fromvertical test to operation in modules 28th Linear Accelerator Conference, LINAC2016, Meeting locationEast Lansing, USA, 25 Sep 2016 - 30 Sep 2016 6 pp., (2016) [10.3204/PUBDB-2017-01886]   More than 800 resonators have been fabricated, verti-cally qualified and operated in module tests before the accelerating module installation in the linac, which will be completed before the conference. An analysis of this experience, with correlation of the final cavity perfor-mances with production, preparation and assembly stages, is underway and at the time of the conference a summary of the activities will be available.. OpenAccess: PDF; 2017-04-2514:46 [PUBDB-2017-01883] Preprint/Report Schaffran, J. Analysis of the cool down related cavity performance of the European XFEL vertical acceptance tests [arXiv:1609.06503]   It has been reported that the cool down dynamics across $T_c$ has a significant influence on the observed quality factors $Q_0$ of a cavity, which is most likely due to trapped flux. In this document we show the results of the investigation if such a correlation can be observed during the European XFEL cavity production.. OpenAccess: PDF; External link: Fulltext 2017-04-2514:30 [PUBDB-2017-01882] Journal Article et al Performance in the vertical test of the 832 nine-cell 1.3 GHz cavities for the European X-ray Free Electron Laser   The successful production and associated vertical testing of over 800 superconducting 1.3 GHz accelerating cavities for the European X-ray Free Electron Laser (XFEL) represents the culmination of over 20 years of superconducting radio-frequency R&D. The cavity production took place at two industrial vendors under the shared responsibility of INFN Milano–LASA and DESY. [...] OpenAccess: PDF; External link: Fulltext 2017-04-2513:09 [PUBDB-2017-01878] Journal Article Kärtner, F. X. THz cavities and injectors for compact electron acceleration using laser-driven THz sources   We present a design methodology for developing ultrasmall electron injectors and accelerators based on cascaded cavities excited by short multicycle THz pulses obtained from laser-driven THz generation schemes. Based on the developed concept for optimal coupling of the THz pulse, a THz electron injector and two accelerating stages are designed. [...] OpenAccess: PDF; 2017-04-2512:23 [PUBDB-2017-01875] Journal Article et al Laser control over the ultrafast Coulomb explosion of N$_{2}$$^{2+} after Auger decay: A quantum-dynamics investigation Physical review / A 95(4), 043419 (2017) [10.1103/PhysRevA.95.043419] By theoretical calculation, we demonstrate the possibility to control and partially suppress the Coulomb explosion of N_2 molecules after core-level photoionization by an x-ray laser and subsequent Auger decay. This is achieved by means of a femtosecond infrared laser pulse interacting with the N_{2}$$^{2+}$ dication produced by the x-ray pulse [...] OpenAccess: PDF; 2017-04-2416:59 [PUBDB-2017-01848] Journal Article et al Elucidation of the helical spin structure of FeAs Physical review / B 95(6), 064424 (2017) [10.1103/PhysRevB.95.064424]   We present the results of resonant x-ray scattering measurements and electronic structure calculations on the monoarsenide FeAs. We elucidate details of the magnetic structure, showing the ratio of ellipticity of the spin helix is larger than previously thought, at 2.58(3), and reveal both a right-handed chirality and an out-of-plane component of the magnetic moments in the spin helix. [...] OpenAccess: PDF; 2017-04-2414:34 [PUBDB-2017-01838] Report/Journal Article Schweizer, J. Flavor mixings in flux compactifications [DESY-16-238; arXiv:1701.06935] Physical review / D 95(7), 075024 (2017) [10.1103/PhysRevD.95.075024]   A multiplicity of quark-lepton families can naturally arise as zero-modes in flux compactifications. The flavour structure of quark and lepton mass matrices is then determined by the wave function profiles of the zero-modes. [...] OpenAccess: PDF;