# Ph.D. Theses

 2017-10-2011:16 [PUBDB-2017-11458] Report/Dissertation / PhD Thesis Thun, H.-J. Asymptotic behaviour at exceptional momenta [DESY-74-004] [S.l.] : Italian Physical Society, (1975) [10.1007/BF02900512] = Universität Hamburg, Diss., 1974   We develop a method for investigating the asymptotic behaviour of vertex functions at certain Minkowskian exceptional momenta. It is a direct generalization of earlier treatments of Euclidean exceptional momenta. [...] OpenAccess: PDF PDF (PDFA); 2017-10-1813:21 [PUBDB-2017-11443] Dissertation / PhD Thesis Ippen, E. P. All-Optical Electron Acceleration with Ultrafast THz Pulses 210 pp. (2017) = Massachusetts Institute of Technology, Diss., 2017 This thesis discusses a series of advances toward - and resulting in -the demonstration of the first ultrafast THz-driven electron gun, a technology with the potential to deliver unprecedented electron beam quality to scientists studying matter at the ultrafast and ultrasmall scale via electron diffraction or x-ray imaging. In Part 1, we discuss various advances in generation of high energy pulsed THz radiation, a spectral regime uniquely effective at accelerating electrons but historically lacking in effcient sources. [...] Restricted: PDF PDF (PDFA); 2017-10-1718:02 [PUBDB-2017-11438] Book/Report/Dissertation / PhD Thesis Weiglein, G. Interplay of Higgs Phenomenology and New Physics in Supersymmetric Theories [DESY-THESIS-2017-041] Hamburg : Verlag Deutsches Elektronen-Synchrotron, DESY-THESIS, 169 pp. (2017) [10.3204/PUBDB-2017-11438] = Universität Hamburg, Diss., 2017   OpenAccess: desy-thesis-17-041.title - PDF PDF (PDFA); thesis_patel - PDF PDF (PDFA); 2017-10-1313:31 [PUBDB-2017-11374] Book/Report/Dissertation / PhD Thesis Schlarb, H. Pilot Study of Synchronization on a Femtosecond Scale between the Electron Gun REGAE and a Laser-Plasma Accelerator [DESY-THESIS-2017-040] Hamburg : Verlag Deutsches Elektronen-Synchrotron, DESY-THESIS, 158 pp. (2017) [10.3204/PUBDB-2017-11374] = Universität Hamburg, Diss., 2016   Laser wakefield acceleration (LWFA) is a novel technique to accelerate charged particles. Acceleration is achieved by a high-power laser pulse transmitting a gas target where electrons and ions form a strong wakefield with gradients up to 100 GV/m. [...] OpenAccess: PhD_Thesis_Mikheil_Titberidze - PDF PDF (PDFA); desy-thesis-17-040.title - PDF PDF (PDFA); 2017-10-0914:16 [PUBDB-2017-11222] Book/Report/Dissertation / PhD Thesis Maier, A. High energy multi-cycle terahertz generation [DESY-THESIS-2017-039] Hamburg : Verlag Deutsches Elektronen-Synchrotron, DESY-THESIS, 198 pp. (2017) [10.3204/PUBDB-2017-11222] = Universität Hamburg, Diss., 2017   Development of compact electron accelerators and free-electron lasers requires novel acceleration schemes at shorter driving wavelengths. The Axsis project seeks to developterahertz based electron acceleration as well as the high energy terahertz sources required. [...] OpenAccess: desy-thesis-17-039.title - PDF PDF (PDFA); Frederike-Ahr-PhDThesis - PDF PDF (PDFA); 2017-08-2616:35 [PUBDB-2017-09888] Dissertation / PhD Thesis Stierle, A. Resonant Hard X-ray Ptychography for High-Sensitivity Imaging with Chemical Contrast 125 pp. (2017) [10.3204/PUBDB-2017-09888] = University of Hamburg, Diss., 2017   For the detailed investigation of biological, chemical or physical processes on the nano scale, high-resolution imaging techniques are essential. For this purpose, the coherentimaging technique – X-ray ptychography – has been established in recent years. [...] OpenAccess: PDF PDF (PDFA); 2017-08-2108:02 [PUBDB-2017-09563] Dissertation / PhD Thesis Herzog, G. Erforschung von Prozessen an nanostrukturierten Oberflächen mit Röntgenkleinwinkelstreuung unter streifendem Einfall 139 pp. (2015) = University of Hamburg, Diss., 2016 2017-08-1509:47 [PUBDB-2017-09253] Book/Report/Dissertation / PhD Thesis Louis, J. Aspects of Six-Dimensional Flux Compactifications [DESY-THESIS-2017-036] Hamburg : Verlag Deutsches Elektronen-Synchrotron, DESY-THESIS, 141 pp. (2017) [10.3204/PUBDB-2017-09253] = Universität Hamburg, Diss., 2017   In this thesis we investigate various aspects of ux compactications in six-dimensionalquantum eld theories. After introducing the internal geometries, i.e. [...] OpenAccess: PhD_Thesis_Markus_Dierigl_Pub - PDF PDF (PDFA); desy-thesis-17-036.title - PDF PDF (PDFA); 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; 2017-08-1016:14 [PUBDB-2017-09144] Book/Dissertation / PhD Thesis Techert, S. Insights into Protein Dynamics by Time-resolved X-ray Scattering 150 pp. (2015) = Georg-August-Universität Göttingen, Diss., 2014