Physikalisches Kolloquium Mainz

Programm für das Sommersemester 2020

Tuesdays, 16 Uhr c.t.

Institut für Kernphysik, Remote Seminar

live at Zoom
28.04.20Magdalena Kowalska, CERN/ U Genf
When we polarise the spins of unstable nuclei, their beta emission will be asymmetric, due to the parity non-conservation of the weak interaction. This feature has been used by our team in a variety of fields. It is a way to look for New Physics through the determination of the Vud matrix element of the CKM quark mixing matrix in nuclear mirror decays. In nuclear physics, in allows to apply an ultrasensitive type of NMR (called beta-NMR) to determine the magnetic dipole moments and electric quadrupole moments of short-lived nuclei. Recently, we have started applying beta-NMR to chemistry and biology, since its sensitivity is up to a billion times higher than in conventional NMR. In this talk I will introduce spin polarisation via optical pumping and beta-NMR principles. I will present our experimental setup located at CERN/ISOLDE. Finally, I will discuss the three scientific topics: Vud from 35Ar decay, magnetic moment of 26Na with ppm accuracy, and the interaction of Na with DNA G-Quadruplex structures .
16:15 Uhr s.t., at Recording of the presentation

05.05.20Joachim Peinke, Universität Oldenburg
The current development of wind energy is summarised, and it is shown that wind energy has become one of the cheapest ways to produce electrical energy. From the perspective of a physicist there are several challenging research questions which arise, although wind energy systems have been used already over several centuries. A central point of this talk will be to show how fundamental research in physics can contribute to the modern development of wind energy systems.
16:15 Uhr s.t., at Recording of the presentation

12.05.20Jeff Hangst, Aarhus University
16:15 Uhr s.t., online (zoom oder BigBlueButton)


19.05.20Jan Meijer, Universität Leipzig
The key technology to fabricate quantum devices, i.e. devices that employ single atoms or defects as functional unit is the addressing of single atoms in a solid with high lateral resolu-tion. Whereas the manipulation of single atoms at the surface has been possible since several years, the three dimensional addressing in the bulk requires more effort. The combination of surface manipulation and overgrowth is one possibility but technologically very challenging. Ion beam implantation allows addressing single countable atoms inside a given solid with nanometer precision. To meet this goal we firstly need to focus or collimate the ion beam and to count the ions delivered to the sample. Our approach is to detect a single ion during fly-by using image charge detection and to deliver the ion with nanometer precision employ-ing a modified commercial FIB system. However, to create a deterministic quantum register based on NV centers a third requirement has to be considered: The implanted nitrogen atom has to be converted into an NV center with nearly 100% efficiency. Unfortunately, the creation of vacancies by ion impact is a statistical process and therefore not predictable. Additionally, the charge state of the NV center has to be converted into the negative state to make it functional. The talk will discuss the state of the art of single ion nano-implantation methods as well as new developments in material science to overcome the limitations encountered in the crea-tion of NV centers so far.
16:15 Uhr s.t., at Recording of the presentation

26.05.20Achim Rosch, Universität Köln
Magnetic skyrmions are tiny, topologically quantized magnetic whirls stabilized by relativistic spin-orbit interactions. They couple extremely efficiently to charge-, spin- and heat currents and can be manipulated by ultra small forces. They are therefore promising candidates for, e.g., future magnetic memories. The coupling of skyrmions to electrons can efficiently be described by artifical electromagnetic fields. We explore how these fields can be measured. Phase transitions in and out of the skyrmion phase are driven by topological point defects which can be identified as emergent magnetic monopoles.
16:15 Uhr s.t., at Recording of the presentation

02.06.20Laura Baudis, University of Zurich
Neutrinos are the only known elementary particles that are Majorana fermion candidates, implying that they would be their own antiparticles. The most sensitive and perhaps only practical probe of the Majorana nature of neutrinos is an extremely rare nuclear decay process, the double beta decay without the emission of neutrinos. After an introduction to the physics of neutrinoless double beta decay, I will present the experimental techniques to search for this exceedingly rare process. I will show the latest results from leading experiments in the field, then discuss future projects and their prospects to probe the inverted neutrino mass ordering scenario.
16:15 Uhr s.t., at Recording of the presentation

09.06.20Martin Fertl, JGU Mainz
Muon g-2: Comparing the Muon’s Clocks to Test the Standard Model of Particle Physics
16:15 Uhr s.t., at Recording of the presentation

16.06.20Joachim Mnich, DESY
Over the last years, intense discussions on the international level have started on the future perspectives of particle physics after the LHC era. In Europe, CERN Council has initiated an update of the European Strategy, supposed to conclude in spring 2020. This schedule might slip because of the current Covid-19 pandemic, but some possible directions for the field have been identified in the community discussions. These include plans for Higgs factories to study this very peculiar particle to highest precision as well as ideas for future hadron colliders with a significantly higher energy reach than the LHC. All of these projects will require large resources and can only be realized through global collaboration. It is therefore important to formulate a global strategy for particle physics, including for instance the USA in which the community discussions (Snowmass process) are starting now – with results expected in about a year. The International Committee for Future Accelerators (ICFA), which includes members from all world, regions will provide a forum for discussions towards a global strategy. The talk will summarize the status of these discussions and try to provide an outlook into the future.
16:15 Uhr s.t., at Recording of the presentation

23.06.20Rafael Lang, Purdue University, Indiana, USA
I will review the science case for dark matter, presenting the evidence from cosmology and astrophysics. As will thus become clear, dark matter has already been discovered - we just don't know yet what it is made of. The so-called direct detection of dark matter is a very promising approach to tackle this question. I will present the status of this field, including the recently announced results from XENON1T.
16:15 Uhr s.t., at Recording of the presentation

30.06.20Jo van den Brand, Nikhef
The LIGO Virgo Consortium achieved the first detection of gravitational waves. A century after the fundamental predictions of Einstein, we report the first direct observations of binary black hole systems merging to form single black holes. The detected waveforms match the predictions of general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. Our observations provide unique access to the properties of space-time at extreme curvatures: the strong-field, and high velocity regime. It allows unprecedented tests of general relativity for the nonlinear dynamics of highly disturbed black holes. In 2017 the gravitational waves from the merger of a binary neutron star was observed. This discovery marks the start of multi-messenger astronomy and the aftermath of this merger was studied by using 70 observatories on seven continents and in space, across the electromagnetic spectrum. The scientific impact of the recent detections on nuclear physics will be explained. In addition key technological aspects will be addressed, such as the interferometric detection principle, optics, and sensors and actuators. Attention is paid to Advanced Virgo, the European detector near Pisa that recently came on-line. The presentation will close with a discussion of the largest challenges in the field, including plans for a detector in space (LISA), and Einstein Telescope, an underground observatory for gravitational waves science.
16:15 Uhr s.t., at Recording of the presentation

07.07.20Paul Dodds, University College London
Hydrogen caused an energy revolution when it was introduced from the early 1810s.  Might we return to using hydrogen again in the future?  Paul will examine the potential future roles of hydrogen and fuel cells across the economy, including for vehicles, heating your home and office, powering industry, and integrating renewable electricity generation.  He will examine the innovation challenges and opportunities for hydrogen and fuel cells, from both engineering and economic perspectives.  Finally he will compare them with alternative low-carbon technologies to try to understand which of these roles are most likely to be realised.
16:15 Uhr s.t., at Zoom (for more details see below)

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Prof. Dr. Uwe Oberlack
Institut für Physik, ETAP

Prof. Dr. Achim Denig
Institut für Kernphysik

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