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G. Otto, GSI Helmholtzzentrum für Schwerionenforschung

26.07.2022 | 

GSI and FAIR mourn the loss of one of their most prominent scientists. Prof. Dr. Sigurd Hofmann, one of the world leaders in the discovery of new elements, passed away on June 17, 2022 at the age of 78. During his time as head of the Heavy Elements Department, he succeeded in discovering the elements darmstadtium, roentgenium and copernicium. In the years before, he made significant contributions to the synthesis of the elements hassium, bohrium, and meitnerium. Equally remarkable in his scientific life is the discovery of proton radioactivity, which was achieved at the SHIP experimental setup in 1981.

Sigurd Hofmann was born on February 15, 1944 in Böhmisch-Kamnitz, Bohemia and came to Groß-Umstadt (near Darmstadt) shortly after the end of the second world war. He went to school there and attended the Max Planck High School until 1963. He then began studying physics at the former TH Darmstadt (now TU Darmstadt), where he received his diploma in 1969 and his doctorate in 1974 with Egbert Kankeleit. His scientific work, which he then began at GSI in Darmstadt, occupied him for almost 50 years. Most recently, he worked on a book on the current state of worldwide heavy element research and on the publication of a method for energy calibration of semiconductor detectors, which he had already developed in the 1990s - accuracy and scientific exactness were always important to him. After joining GSI in 1974, he devoted himself to investigating fusion reactions and radioactive decays in the group of Peter Armbruster and worked together with Gottfried Münzenberg. Sigurd Hofmann achieved international fame through the discovery of proton radioactivity from the ground state of lutetium-151 in 1981, a previously unknown decay mechanism. When analyzing the data, he benefited from his pronounced thoroughness and scientific curiosity.

At the same time, Sigurd Hofmann had 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, Z=107), hassium (Hs, Z=108) and meitnerium (Mt, Z=109) in the years 1981 to 1984, with which GSI for the first time – and at the same time very prominently ¬¬– entered the international stage of this renowned research field. The semiconductor detectors, that Sigurd Hofmann had developed specifically for these experiments, were crucial here. Far ahead of its time, such detectors are now used worldwide to search for new chemical elements. At the end of the 1990s, Sigurd Hofmann took over the management of the heavy element group and - after instrumental improvements at the GSI linear accelerator UNILAC, the velocity filter SHIP, further detectors as well as the detection electronics – he crowned his scientific success with the discovery of the chemical elements darmstadtium (Ds, Z=110), roentgenium ( Rg, Z=111) and copernicium (Cn, Z=112) in the years 1994 to 1996. The concept "SHIP-2000", a strategy paper developed under his leadership in 1999 for long-term heavy element research at GSI, is today still current. In 2009 he was appointed Helmholtz Professor and from then onwards he was able to devote himself entirely to scientific work again. For many years he maintained a very intensive collaboration and scientific exchange with his international colleagues in Dubna, where he co-discovered element flerovium (Fl, Z=114) in a joint experiment.

For his outstanding research work and findings, he received a large number of renowned awards and prizes, of which only the most important ones can be mentioned here. Since 1996 he has been an honorary doctor of the Faculty of Mathematics and Physics at Comenius University in Bratislava (Slovakia), since 1998 honorary professor at Goethe University in Frankfurt am Main, since 2001 Dr. h.c. of the Joint Institute for Nuclear Research (JINR) in Dubna and since 2004 Professor Laureate of the Josef Buchmann Foundation of the Goethe University in Frankfurt am Main. In 1984 he received the Physics Prize of the German Physical Society (together with Gottfried Münzenberg, Willibrord Reisdorf and Karl-Heinz Schmidt), in 1996 the Otto Hahn Prize of the City of Frankfurt am Main (together with Gottfried Münzenberg), in 1997 the G.N. Flerov Prize of the Joint Institute for Nuclear Research (JINR) in Dubna and in 1998 the SUN-AMCO Medal of the International Union of Pure and Applied Physics; in 2011 he received the Nicolaus Copernicus Medal of the Polish Academy of Sciences in Warsaw (Poland) and in 2011 the Medal of the City of Toruń and Nicolaus Copernicus University of Toruń (Poland).

Sigurd Hofmann was a diligent writer and speaker. He has been invited to speak at countless international conferences, authored a large number of review articles, books and book chapters, many widely cited publications etc. He also liked to present scientific results at public events, including as "Confessing Heiner" in the “Darmstadt Ziegelhütte” event location. 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 his contemporary scientific life are recorded in his 2002 book “On Beyond Uranium”. His modesty and friendly nature were remarkable. You could always rely on him. His care, accuracy and deliberateness in all work was outstanding. His persistence was one of the foundations for the groundbreaking scientific achievements he achieved for GSI. He was always in the office or at the experiment, even late in the evening and on weekends, so that you could ask him at any time and always got detailed answers and competent advice. There was practically nothing in nuclear physics or GSI that he didn't know.

We are pleased that we have been able to work with an excellent scientist and colleague as well as an outstanding teacher and great person for so many years. Now we mourn Sigurd Hofmann. Our deepest sympathy goes out to his family. We will remember him fondly. (JL)