"GSI-Colloquium:Physics and chemistry experiments with Superheavy Elements at GSI on the way to FAIR"

Since the birth of GSI and still today, studies of superheavy elements are a pillar of the GSI research program. Six elements (Z=107-112) were discovered here, two (Z=106, 108) had chemical properties measured for the first time in GSI experiments. 270Hs, which is the heaviest known doubly-magic nucleus, was discovered at GSI, and the first direct mass measurements beyond uranium were achieved here. In the past decade, elements with atomic numbers up to Z=118 were claimed, first from experiments at FLNR Dubna, and IUPAC has accepted those with Z=114 and 116 as discovered and they were recently named flerovium (Fl) and livermorium (Lv). Superheavy element research at GSI and the Helmholtz Institute Mainz (HIM) encompasses a variety of aspects of these elements; most pronouncedly their synthesis and decay properties, nuclear structure, atomic mass, and their chemical properties. After an overview over the status of the field, I will discuss in detail experiments on the search for the new elements with Z>118 that were performed at the gas-filled recoil separator TASCA in 2011/12, and on the not yet acknowledged elements with Z=113/115/117. In the second part I will discuss chemical studies of the heaviest elements. A first example focuses on gas phase experiments with Fl in the elemental state, which help answering the question about the nature of this element: noble metal, as generally expected for this heavier homolog of Pb, or noble-gas-like, as predicted for a long time? A second example concerns the synthesis of the first carbonyl-complex of a superheavy element, Sg(CO)6, which was achieved in 2013. I will close with discussing the perspectives of SHE research at the GSI/FAIR facility, highlighting synergies between SHE and FAIR, and the research possibilities arising from the development of a compact superconducting continuous wave linac, largely driven by scientists from HIM, GSI, and Frankfurt University. A first cavity is currently under construction and serves as a prototype for a new acceleration concept. The next step includes the design of an advanced demonstrator consisting of five cavities.