Long-lived radionuclides are powerful tools in experimental astrophysics, offering insights into stellar evolution and nucleosynthesis. Their detection, however, is highly challenging: long half-lives preclude decay counting, while isotopic ratios can be as low as 10⁻¹⁵. Only advanced techniques such as Accelerator Mass Spectrometry (AMS) are able to solve the difficulties of direct detection related to immense molecular background and isobaric interference. Over the past decades developments especially at ETH Zurich cumulated in state-of-the art AMS systems such as the MICADAS and MILEA systems that are compact, highly efficient and precise.
During my talk, I will take you on a brief journey through a selection of my own experiments with radionuclides in experimental astrophysics. These studies cover radionuclides of very different half-lives and astrophysical origins: 182Hf (8.9 Myr, r- and s-process), 44Ti (59 yr, a-rich freezeout), 23Mg (11.3 s, classical novae) - and each require its own sophisticated dedicated detection technique ranging from AMS at various laboratories to the DRAGON recoil spectrometer at radioactive beam facility ISAC-TRIUMF. Our measurements improved half-life determinations and constrained key production and destruction reactions at stellar energies.
Furthermore, cosmogenic radionuclides such as 14C, 10Be or 36Cl can reveal insights of our closest star, the sun. Recently, so-called solar energetic events have been detected as production anomalies of these radionuclides preserved in tree rings and ice cores. At ETH, we have studied several of these events in detail, using all three radionuclides with the advanced AMS detection methods developed in our laboratory.
The journey ends with an outlook on experimental possibilities to expand the measurement capabilities that go beyond classical AMS by using photons for isobar separation, atom trapping and efficient radionuclide detection.
As part of the presentation, there will be a teaching demonstration on the topic "The classical and the quantum harmonic oscillator".
