ERIK MCLEAN / UNSPLASH

Physikalisches Kolloquium

Freitag, 16. Oktober 2026 17:00 Uhr  Modern Nuclear Physics and the Study of Exotic Decays of Nuclei

Prof. Dr. Yury A Litvinov , GSI Helmholtz Center for Heavy Ion Research GmbH From Nuclei to Stars: β Decay of Highly Charged Ions Yury A. Litvinov GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany Institut für Kernphysik, Universität zu Köln, 50937 Köln, Germany The famous phrase "we are all made of stardust" reflects a profound truth: nearly all visible matter in the Universe was forged in stellar interiors. Nucleosynthesis proceeds by nuclear fusion up to iron, beyond which nature relies on neutron capture and β-decay to build heavier elements. Yet our knowledge of β-decay rests almost entirely on studies of neutral atoms — a poor proxy for the interiors of stars, where atoms are stripped of most or all of their electrons. In this presentation we will show that decay properties can change dramatically for highly charged ions (HCI). Familiar radioactive decay channels can be blocked. New ones, unavailable to neutral atoms, can open up. These effects arise from the interplay between the electron shell and the nucleus, making them relevant to nuclear structure and stellar nucleosynthesis, as well as to atomic physics in its own right. Such measurements are carried out at the Experimental Storage Ring (ESR) at GSI, Darmstadt, presently the only facility dedicated to precision decay studies of HCIs, where freshly produced radionuclides are stored in ultra-high vacuum, preserving their high atomic charge state for extended periods.

Teilchenkolloquium

Towards chromatic calorimetry using nanocomposites

Dr. Anne-Mazarine Lyon, CERN, Genf Towards chromatic calorimetry using nanocomposites Dr. Anne-Mazarine Lyon CERN, Genf The development of advanced detector technologies is key to the success of nextgeneration high-energy physics experiments, such as at the FCC-ee. In this context, quantum-engineered scintillating materials open new opportunities for innovative detector designs. One such concept is chromatic calorimetry, a novel approach to homogeneous electromagnetic calorimetry that reconciles detector homogeneity with longitudinal segmentation of particle showers. In this seminar, I first present the experimental validation of a proof-of-concept chromatic calorimeter. The detector is based on standard scintillating materials emitting in distinct wavelength ranges, combined with a spectrally dependent readout system. Results on shower profile reconstruction and energy calibration are discussed, demonstrating the potential of this approach. I then present prospects for implementing chromatic calorimetry using nanocomposite scintillators, consisting of quantum dots embedded in a polymer matrix. These materials are particularly promising due to their narrow, tunable emission spectra and their exceptionally fast timing capabilities. I review the current status of the production of nanocomposites based on cesium lead halide and discuss their scintillation properties in view of future applications in calorimetry.

Astronomisches Kolloquium

Dienstag, 20. Oktober 2026 16:30 Uhr  Again! - but faster, better, and with more physics: ML-accelerated inference of galaxy properties in deep and wide surveys of the universe

Joel Leja, Penn State University The inference of the physical properties of galaxies at cosmological distances requires modeling a wide range of physics, including stellar evolution and atmospheres, dust attenuation and re-emission, nebular physics, AGN emission, and more. Bayesian inference is often used to map this space, and the wide range of physics and large parameter space (30-40 dimensions!) means these codes are not fast. Yet current and near-future surveys yield spectra for millions of galaxies, and imaging for billions. I will introduce the next-generation solutions, ranging from neural net emulators of core physics (photoionization modeling; stellar spectra), to efficient gradient-aware, GPU-native sampling, to rapid simulation-based inference. These yield speed-ups of between hundreds and millions, with different trade-offs in flexibility and accuracy. In addition to permitting sophisticated high-dimensional modeling on the industrial scales of modern surveys, I will discuss qualitatively new science directions enabled by these breakthroughs, such as modeling entire galaxy populations rather than one galaxy at a time, extremely high-dimensional modeling of individual systems (e.g. spatially resolved modeling), and new data-driven approaches that learn the priors directly from the data, all together with the promise to finally address critical systematics endemic to studies of distant galaxies. To arrange a visit with the speaker during the visit, please contact their host: Anna de Graaff

Zentrum für Quantendynamik Kolloquium

Mittwoch, 4. November 2026 16:30 Uhr  tba

Prof. Dr. Leticia Tarruell, ICFO – The Institute of Photonic Sciences, Spain