DESY Doctoral Researchers Online Conference

19 Aug 2020, 09:30 → 20 Aug 2020, 12:00 Europe/Berlin

Online

Did you have a conference that was cancelled this summer? Were you planning on giving a talk? If you are reading this text, that’s pretty much a guarantee. Even in these times of virus and unrest, our research continues. With most of the normal avenues gone, wouldn’t it be nice to have a place to practice your speaking skills in preparation for your defense or other high profile engagement? If you agree, then please join us for the first annual DESY Doctoral Researchers Online Conference!

Wednesday, 19 August

Session 1.1

1 Search for GeV-scale decaying sterile neutrinos with IceCube DeepCore

IceCube is a cubic kilometer ice Cherenkov detector located at the South Pole that can be used to test models describing the production and decay of particles not included in the standard model. This talk introduces a novel analysis searching for heavy neutral lepton signals using DeepCore, a dense sub-array of IceCube capable of detecting particle interactions at energies as low as 10GeV.

Speaker: Mr Leander Fischer (DESY Zeuthen)

2 (Magnetic) x-ray standing waves

The presentation will provide a brief introduction the x-ray standing wave method. Laying in between spectroscopy and diffraction, the technique is used to study the atomic structure of materials in the direct way. In the second part, the extension of the method for magnetic structures will be presented.

Speaker: Michal Kaminski

10:20 Coffee Break

Session 1.2

3 Very-High-Energy Emission from Gamma-Ray Burst Afterglows

The recent, unprecedented detection of gamma-ray burst afterglows at very high energies (VHE) opens a new window on the radiative processes at work. I will discuss the limitations of its interpretation as synchrotron-self Compton (SSC) radiation being a natural extension of the standard fireball model.

Speaker: Mr Marc Klinger (DESY Zeuthen)

4 Design of Photon Mask for the Helical Undulator at ILC-250GeV

The positron source of the International Linear Collider (ILC) is based on a superconducting helical undulator passed by the high-energy electron beam to generate photons which hit a conversion target. Since the photons are circularly polarized the resulting positron beam is longitudinally polarized. At a center-of-mass energy of 250 GeV (ILC-250), the undulator with 231 m magnet length is needed to produce the required number of positrons. The power deposition in the undulator walls should be below the acceptable limit of 1 W/m since it is a superconducting undulator and also to fulfill the vacuum requirements. The power deposition of the photon beam in undulator walls was studied and shown that the peak power deposition in the undulator walls is above 20 W/m. To keep the power deposition below the acceptable limit, 23 photon masks must be inserted in the undulator line. In this paper the design of photon masks for an ideal and non-ideal helical undulator is presented and the power deposition in the undulator walls is discussed.

Speaker: Mr Khaled Alharbi (Hamburg Uni-DESY)

Session 2.1

5 Search for Primordial Black Holes with Optical Microlensing by Imaging Air Cherenkov Telescopes

Primordial black holes (PBHs) are viable candidates for dark matter. The microlensing of stars is a powerful method to constrain their abundance. Imaging Air Cherenkov Telescopes (IACTs), which are designed for gamma-ray astronomy, also provide outstanding optical capabilities with sampling speeds of $\ll 1\,$s. This work investigates, whether IACTs can access the unexplored PBH mass window of $10^{-14}\,M_\odot\leq M_{PBH} \leq10^{-10}\,M_\odot$.

Speaker: Konstantin Pfrang (DESY Zeuthen)

6 The 'shocking' effects of slow compression experiments on quartz crystals using diamond anvil cells

Mineral specimens recovered from meteorites or impact sites on Earth typically exhibit shock metamorphic effects, providing insights into past impact events within the solar system. Simulating impacts by diamond anvil cells in slow motion, we perform compression experiments on quartz to better understand the formation of natural impact effects.

Speaker: Mr Christoph Otzen (DESY)

14:50 Coffee Break

Session 2.2

7 The gamma-ray source morphology with H.E.S.S.: latest results

The High Energy Stereoscopic System (H.E.S.S.) is a gamma-ray experiment composed of five Cherenkov telescopes and located in Namibia. Numerous gamma-ray sources have been detected since the start of operations in 2004, many of them physically extended. Yet, some sources are expected to be extended at the detection limit of H.E.S.S. New analysis methods, hardware upgrades as well as sophisticated Monte-Carlo simulations allowed the H.E.S.S. collaboration to investigate further details in the already detected sources. Understanding the morphology of the gamma-ray emission helps building a complete model for the source emission in a Multi-wavelength (MWL) scenario and sheds light on the origin of the accelerated particles. The latest findings regarding the extension of Galactic and extra-galactic sources are presented. Prospects for the Cherenkov Telescope Array (CTA), the next generation gamma-ray telescopes, are discussed.

Speaker: Mr Victor Barbosa Martins (Desy)

Thursday, 20 August

Session 3.1

8 Axion gegenschein: dark countersources of bright radio objects

We propose a novel scenario for the detection of radio signals from the decay of axions and axion-like particles, termed *axion gegenschein*. Ambient radiation arriving from astrophysical radio-bright objects stimulate the decay of halo dark matter in Milky Way creating a *countersource* emitting photons at frequencies half the axion mass and exhibiting the spatial dimensions and features of each radio object in a direction precisely opposite to it. This technique for the indirect detection of axion dark matter is more powerful compared to radio observations of dwarf spheroidals, and can be advantageous in measuring dark matter overdensities, in the form of minihalos, clumps, and spikes, at large distances.

Speaker: Oindrila Ghosh (DESY Hamburg)

9 Characterization of integrated THz waveguides for electron manipulation

Emerging high power THz sources show great promise for electron acceleration and manipulation within mm-scale waveguides. For efficient and phase synchronous interaction a thorough characterization of these waveguides is required for which a technique has been developed and tested.

Speaker: Max Kellermeier (DESY)

10:20 Conference Closing