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ARES is a planned linear accelerator for R&D for production of ultra-short electron bunches. It will be hosted at the SINBAD facility, at DESY in Hamburg*. The goal of ARES is to produce low charge (0.2-50pC), ultra-short (from few fs to sub-fs) bunches, with high arrival time stability (less than 10fs) for various applications, such as external injection for Laser Plasma Wake-Field acceleration**. The baseline layout of the accelerator foresees an S-band photo-injector which compresses low charge electron bunches via velocity bunching and accelerates them to 100 MeV energy. In the second stage, it is planned to install a third S-band accelerating cavity to reach 200 MeV as well as two X-band cavities: One for the linearization of the longitudinal phase space (subsequently allowing an improved bunch compression) and another one as a transverse deflecting cavity for longitudinal beam diagnostics. Moreover a magnetic bunch compressor is envisaged allowing to cut out the central slice of the beam*** or hybrid bunch compression., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

Enormous progress in compact plasma accelerators has been demonstrated over the recent years in various experiments. These experiments rely on high power, pulsed lasers or short electron bunches to excite ultra-strong wakefields in plasmas. Accelerating gradients have reached several 10 GV/m up to 100 GV/m and the absolute energy gain of electron beams is in the regime of several GeV to 30 GeV. The principle and potential of plasma accelerators has been proven impressively and performance parameters are steadily improving. It is noted that particle accelerators are powerful tools that are ultimately justified by their applications in science, medicine or industry. The demonstration of useable beam quality and a realistic use case remains to be achieved for plasma accelerators. The accelerator physics challenges to arrive at this goal are analyzed and discussed., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Journal of High Energy Physics 2012. 3 (2012): 020 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA), Scaled momentum distributions for the strange hadrons KS0 and Λ/Λ were measured in deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 330 pb-1. The evolution of these distribuitions with the photon virtuality, Q2, was studied in the kinematic region 10 < Q2 < 40000 GeV2 and 0.001 < x < 0.75, where x is the Bjorken scaling variable. Clear scaling violations are observed. Predictions based on different approaches to fragmentation were compared to the measurements. Leading-logarithm parton-shower Monte Carlo calculations interfaced to the Lund string fragmentation model describe the data reasonably well in the whole range measured. Next- to-leading-order QCD calculations based on fragmentation functions, FFs, extracted from e+e- data alone, fail to describe the measurements. The calculations based on FFs extracted from a global analysis including e+e-, ep and pp data give an improved description. The measurements presented in this paper have the potential to further constrain the FFs of quarks, anti-quarks and gluons yielding KS 0 and Λ/ Λ̄ strange hadrons., We thank the DESY Directorate for their strong support and encouragement. The remarkable achievements of the HERA machine group were essential for the successful completion of this work and are greatly appreciated. We are grateful for the support of the DESY computing and network services

Learning objectives Background Imaging findings OR Procedure details Conclusion Personal Information References, Learning objectives: To illustrate typical patterns of bone marrow edema associated with diverse musculoskeletal pathologies throughout the...

In order to achieve high quality electron beams by laser-driven plasma acceleration with external injection, sub-fs bunches with a few fs arrival-time jitter are required. SINBAD (Short Innovative Bunches and Accelerators at DESY) is a proposed dedicated accelerator research and development facility at DESY. One of the baseline experiment at SINBAD is ARES (Accelerator Research Experiment at SINBAD), which will provide ultra-short electron bunches of 100 MeV to one or two connected beam lines. We present start-to-end simulation studies of sub-fs bunches generation at ARES using a magnetic compressor with a slit. In addition, the design of a dogleg with tunable R56 for the second beamline is also presented., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

ARES is a planned linear accelerator for research and development in the field of production of ultra-short electron bunches. The goal of ARES is to produce low charge (0.2-50pC), ultra-short (from few fs to sub-fs) bunches, with improved arrival time stability (less than 10fs) for various applications, such as external injection for Laser Plasma Wake-Field acceleration. The ARES layout will allow to perform and compare different kind of conventional e-bunch compression techniques, such as pure velocity bunching*, hybrid velocity bunching (i.e. velocity bunching plus magnetic compression) and pure magnetic compression with the slit insertion**. This flexibility will allow to directly compare the different methods in terms of arrival time stability and local peak current. In this paper we present simulation results for the compression of an electron bunch with 0.5 pC charge. We compare the case of pure velocity bunching compression to the one of a hybrid compression using velocity bunching plus a magnetic compressor., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

One of the important milestones to make plasma acceleration a realistic technology for user-applications is demonstration of bunch acceleration inside a plasma wake with minimal degradation of its quality. This can be achieved by external injection of beams into a plasma accelerator. SINBAD is a proposed dedicated accelerator research and development facility at DESY where amongst other topics laser-driven wakefield acceleration with external injection of ultra-short bunches will be exploited. To minimise energy-spread growth the bunch should occupy a small fraction of the plasma wavelength. In addition it has to be longitudinally synchronised with the laser driver to high accuracy. To avoid emittance growth the beam Twiss parameters have to be matched to the intrinsic beta-function of the plasma. To facilitate matching and synchronisation, acceleration at low plasma densities can be advantageous. We present a preparatory feasibility study for future plasma experiments at SINBAD using simulations with the particle-in-cell code OSIRIS. Field-gradient scaling laws are presented together with parameter scans of externally injected bunch, such as its injection phase, charge and length., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Generation of ultra-short electron bunches with a few femtoseconds arrival-time jitter is the major challenge in plasma acceleration with external injection. Meanwhile, peak current stability is also one of the crucial factors for user experiments when the electron bunch is used for free-electron laser (FEL) generation. ARES (Accelerator Research Experiment at SINBAD) will consist of a compact S-band normal-conducting photo-injector providing ultra-short electron bunches of 100 MeV. We present bunch arrival-time jitter studies for two different compression schemes, velocity bunching and magnetic compression with a slit, at ARES with start-to-end simulations. Contributions from various jitter sources are quantified., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

A new, dedicated accelerator research facility SINBAD (Short INnovative Bunches and Accelerators at DESY) is proposed. This facility is aimed at promoting two major goals: (1) Short electron bunches for ultra-fast science. (2) Construction of a plasma accelerator module with useable beam quality. Research and development on these topics is presently ongoing at various places at DESY, as add-on experiments at operational facilities. The two research goals are intimately connected: short bunches and precise femtosecond timing are requirements for developing a plasma accelerator module. The scientific case of a dedicated facility for accelerator research at DESY is discussed. Further options are mentioned, like the use of a 1 GeV beam from Linac2 for FEL studies and the setup of an attosecond radiation source with advanced technology. The presently planned conversion of the DORIS storage ring and its central halls into the SINBAD facility is described. The available space will allow setting up several independent experiments with a cost-effective use of the same infrastructure. National and international contributions and proposals can be envisaged., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany