Time, Place:

16:30 ,Seminar room Lindner 339, Gentner lab, 2nd floor

Speaker:

Prof. Qaisar Shafi (Delaware)

Title:

Monopoles, Strings and Gravitational Waves

A variety of interesting topological objects arise in spontaneously broken unified theories. They include monopoles and strings as well as more complex structures withcosmological implications. In this talk I will discuss primordial magnetic monopoles, cosmic strings and gravitational waves.

Time, Place:

11:15 ,Otto Hahn lecture hall, library building

Speaker:

Dr. Pei-Lun He, MPIK

Title:

Photoelectron Polarization Vortexes in Strong-Field Ionization

Abstract: // The spin polarization of photoelectrons induced by an intense linearly polarized laser field is investigated using numerical solutions of the time-dependent Schrödinger equation in companion with our analytic treatment via the spin-resolved strong-field approximation and classical trajectory Monte Carlo simulations. We demonstrate that, even though the total polarization vanishes upon averaging over the photoelectron momentum, momentum-resolved spin polarization is significant, typically exhibiting a vortex structure relative to the laser polarization axis. The polarization arises from the transfer of spin-orbital coupling in the bound state to the spin-correlated quantum orbits in the continuum. The rescattering of photoelectrons at the atomic core plays an important role in forming the polarization vortex structure, while there is no significant effect of the spin-orbit coupling during the continuum dynamics. Furthermore, spin-polarized electron holography is demonstrated, feasible for extracting fine structural information about the atom.

Time, Place:

11:15 ,Grosser Hoersaal/Big Lecture Hall (library)

Speaker:

Dr Christoph Wiesinger

Title:

Probing the neutrino mass with KATRIN and ultra-low background X-ray detectors for IAXO

Our understanding of fundamental particles is incomplete. The absolute neutrino mass remains unknown and strong interactions appear suspiciously symmetric, hinting at the existence of axions. KATRIN performs precision spectroscopy of tritium beta-decay electrons, probing the effective electron anti-neutrino mass with unprecedented sensitivity. IAXO is a next-generation helioscope aiming to detect solar axions, as they are converted into X-rays along a strong magnet pointing towards the sun. In my presentation, I will discuss the challenging analysis of the first five KATRIN neutrino mass campaigns and the potential of ultra-low background semiconductor detectors, based on the TRISTAN upgrade of KATRIN, to boost the search for solar axions with IAXO.