Publications database

The steady-state gamma-ray emission from the Sun is thought to consist of two emission components due to interactions with Galactic cosmic rays: (1) a hadronic disk component, and (2) a leptonic extended component peaking at the solar edge and extending into the heliosphere. The flux of these components is expected to vary with the 11 yr solar cycle, being highest during solar minimum and lowest during solar maximum, as it varies with the cosmic-ray flux. [...]

This thesis studies the reconstruction of top quark-antiquark (t¯t) pairs in the dilepton decay channel, where both top quarks decay leptonically and two neutrinos escape detection. Since the event kinematics are underconstrained, the Sonnenschein algorithm, a fully analytical method used by the CMS and ATLAS experiments at the LHC, where quark-antiquark pairs of the heaviest elementary particle are produced in proton-proton collisions, is applied. [...]

The Large Hadron Collider will be upgraded to extend its lifetime and improve various components. With the upgrade to the High-Luminosity-LHC the instantaneous luminosity will increaseto 5 · 1034 cm−2s−1 and the total integrated luminosity to at least 3000 fb−1. [...]

The outer tracker of the Compact Muon Solenoid (CMS) Detector will be upgraded as part of the upgrade of the Large Hadron Collider (LHC) to the High-Luminosity LHC.The Tracker Endcap Double-Discs (TEDD), that are part of the outer tracker are built and integrated with modules at DESY. The CMS detector and with it the TEDD will be cooled to evacuate the generated heat of the modules, to minimize their leakage current due to the heavy irradiation from the passing through particles and avoid thermal runaway. [...]

In the IceCube Neutrino Observatory, a signal of astrophysical neutrinos is obscured by backgrounds from atmospheric neutrinos and muons produced in cosmic-ray interactions. IceCube event selections used to isolate the astrophysical neutrino signal often focus on t/he morphology of the light patterns recorded by the detector. [...]

Using total and resonant x-ray scattering coupled to large-scale computer modeling, we study the latticemodulations in the complex charge density wave (CDW) material Lu$_2$Ir$_3$Si$_5$ . We find that it is a unique quantumsystem where periodic lattice modulations related to emergent CDW order occur in three orthogonal atomicplanes of the crystal lattice, leading to the emergence of an unusual three-dimensional (3D) pattern of shortand long Ir-Ir and Lu-Lu bonds [...]

2,3-Dihydroxy-1,3,4-trimethyl-6-oxo-1,4-cyclohexadiene-1-carboxylic acid crystallizes in an order–disorder (OD) structure with a high stacking fault probability. The diffraction pattern features diffuse scattering and broad peaks, which can be attributed to fragments of two polytypes of a maximum degree of order (MDO) [...]

In our recent investigation, we utilized a century's worth of archival optical data to search for a decade-long periodicity from the blazar PG 1553+113, finding a hint of a 22-yr period. Building on this foundation, the current study extends our analysis to include 10 blazars from the Fermi-Large Area Telescope Second Catalog of Hard Sources (2FHL) catalogue to uncover similar long-term periodic behaviour. [...]

A wide variety of Galactic sources show transient emission at soft and hard X-ray energies: low- and high-mass X-ray binaries containing compact objects, isolated neutron stars exhibiting extreme variability as magnetars as well as pulsar-wind nebulae. Although most of them can show emission up to MeV and/or GeV energies, many have not yet been detected in the TeV domain by Imaging Atmospheric Cherenkov Telescopes. [...]

Gold ist ein unreaktives Metall und seine chemische Wechselwirkung mit Wasserstoff wird erst seit Kurzem untersucht. Unter Verwendung verschiedener Kohlenwasserstoffe als Wasserstoffquelle beobachten wir hier die Bildung von festem Goldhydrid in der Diamantstempelzelle, die mit einem Freie-Elektronen-Laser beheizt wird. [...]