# FLA

 2017-08-1113:51 [PUBDB-2017-09190] Book/Report/Dissertation / PhD Thesis Wichmann, K. Search for contact interactions and finite quark radius using combined $e^{\pm}p$ data at HERA [DESY-THESIS-2017-035] Hamburg : Verlag Deutsches Elektronen-Synchrotron, DESY-THESIS, 163 pp. (2017) [10.3204/PUBDB-2017-09190] = Universität Hamburg, Diss., 2017   A combination is presented of all previously published deep inelastic neutral and charged current $e^{\pm}p$ scattering measurements at HERA for zero beam polarisation.The ZEUS and H1 collaborations have collected data at electron beam energy of $27.5$ GeV and proton beam energies of $920$, $820$, $575$ and $460$ GeV.The combined data correspond to an integrated luminosity of about $1$ fb$^{-1}$ and cover a kinematic range in the negative four-momentum-transfer squared from $Q^{2} = 0.045$ GeV$^{2}$ to $Q^{2} = 50000$ GeV$^{2}$ and in Bjorken $x$ from $x_{\rm Bj} = 6 \times 10^{-7}$ to $x_{\rm Bj} = 0.65$.The correlations of systematic uncertainties between different sets of data were taken into account, resulting in significantly improved precision.The combined $e^{\pm}p$ cross sections were used in a QCD analysis at next-to-leading order, providing a set of parton distribution functions, called ZCIPDF.The combined measurements were also used in an analysis beyond the Standard Model using a new approach, performing simultaneous fits on large sets of Monte Carlo replicas of parton distribution functions, PDFs, together with the parameters of "new physics" processes.A simplified approach to reduce the calculation time was developed and extensively tested.It allowed the calculation time to be reduced by about a factor of 50.The resulting $95\,\%$ C.L. upper limit on the effective quark radius is $0.43 \cdot 10^{-16}$ cm and the limits on the mass scales for different contact interaction scenarios extend up to $10$ TeV.The analyses have shown that taking into account the possible influence of processes beyond the Standard Model on the PDF parameters is necessary, since the limits that would be obtained using PDFs from QCD analysis within the Standard Model are too strong by about $10\,\%$.Studies of the surface quality of 28 Niobium superconducting radio frequency, SRF, cavities and development of a controllable cooling system for Niobium samples are also reported.The SRF cavities are the core of the accelerating technology for the future International Linear Collider, ILC; the reported studies are part of an ongoing research and development program.. OpenAccess: desy-thesis-17-035.title - PDF PDF (PDFA); Turkot_PhD_Thesis_Search_for_CI_at_HERA - PDF; 2017-06-0813:28 [PUBDB-2017-04531] Report/Journal Article Wenskat, M. Automated Optical Inspection and Image Analysis of Superconducting Radio-Frequency Cavities [DESY-17-061; arXiv:1704.06081] Journal of Instrumentation 12(05), P05016 (2017) [10.1088/1748-0221/12/05/P05016]   The inner surface of superconducting cavities plays a crucial role to achieve highest accelerating fields and low losses. For an investigation of this inner surface of more than 100 cavities within the cavity fabrication for the European XFEL and the ILC HiGrade Research Project, an optical inspection robot OBACHT was constructed. [...] Restricted: PDF PDF (PDFA); 2017-05-3013:29 [PUBDB-2017-03953] Report/Journal Article et al Chirp Mitigation of Plasma-Accelerated Beams by a Modulated Plasma Density [arXiv:1603.08489] Physical review letters 118(21), 214801 (2017) [10.1103/PhysRevLett.118.214801]   Plasma-based accelerators offer the possibility to drive future compact light sources and high-energy physics applications. Achieving good beam quality, especially a small beam energy spread, is still one of the major challenges. [...] OpenAccess: PDF PDF (PDFA); Restricted: PDF PDF (PDFA); External link: Fulltext 2017-05-0309:17 [PUBDB-2017-02181] Report/Contribution to a conference proceedings Schuetz, A. Pair Background Envelopes in the SiD Detector [arXiv:1703.05737] International Workshop on Future Linear Colliders 2016, LCWS2016, Meeting locationMorioka, Japan, 5 Dec 2016 - 9 Dec 2016 1-6 (2017) [10.3204/PUBDB-2017-02181]   The beams at the ILC produce electron positron pairs due to beam-beam interactions. This note presents for the first time a study of these processes in a detailed simulation, which shows that these pair background particles appear at angles that extend to the inner layers of the detector. [...] OpenAccess: PDF; 2017-05-0213:53 [PUBDB-2017-02151] Report/Contribution to a conference proceedings White, G. A Study of the Impact of Muons from the Beam Delivery System on the SiD Performance [arXiv:1703.05738] International Workshop on Future Linear Colliders 2016, LCWS2016, Meeting locationMorioka, Japan, 5 Dec 2016 - 9 Dec 2016 15 pp. (2017) [10.3204/PUBDB-2017-02151]   To suppress the muon background arising from the Beam Delivery System (BDS) of the International Linear Collider (ILC), and to hinder it from reaching the interaction region, two different shielding scenarios are under discussion: five cylindrical muon spoilers with or without an additional magnetized shielding wall. Due to cost and safety issues, the scenario preferred by the Machine-Detector-Interface (MDI) group is to omit the shielding wall, although omitting it also has disadvantages. [...] OpenAccess: PDF; 2017-05-0211:59 [PUBDB-2017-02137] Conference Presentation et al The International Linear Collider - Background Simulations & the Impact on SiD LC Vertex Detector Workshop, Meeting locationSchloss Ringberg, Germany, 30 Apr 2017 - 3 May 2017   The International Linear Collider is a linear $e^{+}e^−$ accelerator, which is unique due to the clean environment and its capability for high precision measurements. To achieve these goals the backgrounds for linear colliders have to be understood in great detail, and both, the machine and the detectors, have to be optimized towards that goal. [...] OpenAccess: PDF; 2017-05-0211:47 [PUBDB-2017-02136] Conference Presentation Schuetz, A. The International Linear Collider - Background Simulations & Optimizing the Final Focus Region DPG 2017, Meeting locationMünster, Germany, 27 Mar 2017 - 31 Mar 2017 The International Linear Collider is a linear $e^{+}e^−$ accelerator, which is unique due to the clean environment and its capability for high precision measurements. To achieve these goals the machine backgrounds for linear colliders have to be understood in great detail, and both, the machine and the detectors, have to be optimized towards that goal. [...] OpenAccess: PDF; 2017-05-0210:39 [PUBDB-2017-02128] Conference Presentation et al BDSIM simulation model of ATF2 & Background Studies for the Vertical Collimator System 20th ATF2 project meeting, Meeting locationGeneva, CERN, Schweiz, 14 Mar 2017 - 15 Mar 2017   ATF2 in Japan is a test facility for the final-focus region of the International Linear Collider. In order to proof the functionality of the recently installed vertical beam halo collimator and its impact on the machine backgrounds, background measurements were done in the proximity of the collimator. [...] OpenAccess: PDF; External link: Fulltext 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 2017-04-2516:03 [PUBDB-2017-01893] Talk (non-conference) et al High-quality electron beam generation in plasma-based accelerators Neumann-Institut für Computing - Vortragsveranstaltung des Wissenschaftlichen Rates, Meeting locationDarmstadt, GSI Darmstadt, Germany, 20 Apr 2017 - 21 Apr 2017