Sigurd Hofmann, an extraordinary scientist, colleague and teacher, passed away on 17 June 2022 at the age of 78. Remarkable in his scientific life was the discovery of proton radioactivity, which was achieved in 1981, as well as the synthesis of six new superheavy chemical elements between 1981 and 1996.
Sigurd was born on 15 February 1944 in Böhmisch-Kamnitz (Bohemia) and studied physics at TH Darmstadt, where he received his diploma in 1969 and his doctorate in 1974 with Egbert Kankeleit. Afterwards, he joined the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, his scientific work there occupying him for almost 50 years. Accuracy and scientific exactness were important to him from the beginning. He investigated fusion reactions and radioactive decays in the group of Peter Armbruster and worked with Gottfried Münzenberg.
Sigurd achieved international fame through the discovery of proton radioactivity from the ground state of 151Lu in 1981, a previously unknown decay mechanism. When analysing the data, he benefited from his pronounced thoroughness and scientific curiosity. At the same time, he begun work on the synthesis, unambiguous identification and study of the properties of the heaviest chemical elements, which were to shape his further scientific life. The first highlights were the synthesis of the new elements bohrium (Bh), hassium (Hs) and meitnerium (Mt) between 1981 and 1984, with which GSI entered the international stage of this renowned research field. The semiconductor detectors that Sigurd had developed specifically for these experiments were far ahead of their time, and are now used worldwide to search for new chemical elements.
At the end of the 1990s Sigurd took over the management of the Separator for Heavy Ion Reaction Products (SHIP) group and, after making instrumental improvements to detectors and electronics, crowned his scientific success with the discovery of the elements darmstadtium (Ds), roentgenium (Rg) and copernicium (Cn) in the years 1994 to 1996. The concept for “SHIP-2000”, a strategy paper developed under his leadership in 1999 for long-term heavy-element research at GSI, is still relevant today. In 2009 he was appointed Helmholtz professor and from then on was able to devote himself entirely to scientific work again. For many years he also maintained an intensive collaboration and scientific exchange with his Russian colleagues in Dubna, where he co-discovered the element flerovium (Fl) in a joint experiment.
For his outstanding research work and findings, Sigurd received a large number of renowned awards and prizes; too many, in fact, to mention. A diligent writer and speaker, he was invited to talk at countless international conferences, authored a large number of review articles, books and book chapters, and many widely cited publications. He also liked to present scientific results at public events. In doing so, he was able to develop a thrilling picture of modern physics, but also of the big questions of cosmology and element synthesis in stars; he was also able to convey very clearly to the public how atoms can be made “visible”.
Many chapters of Sigurd’s contemporary scientific life are recorded in his 2002 book On Beyond Uranium (CRC Press). His modesty and friendly nature were remarkable. You could always rely on him. His care, accuracy and deliberateness in all work were outstanding, and his persistence was one of the foundations for ground-breaking scientific achievements. He was always in the office or at an experiment, even late in the evening and on weekends, so you could talk to him at any time and were always rewarded with detailed answers and competent advice.
We are pleased that we were able to work with such an excellent scientist and colleague, as well as an outstanding teacher and a great person, for so many years.