German nuclear physicist · born 1931
Peter Armbruster
Peter Armbruster led the team at GSI in Darmstadt that discovered six superheavy elements between 1981 and 1996, from bohrium to copernicium. Their success moved the centre of element hunting from the United States and Soviet Union to West Germany.
- Elements credited
- 6
- Discoveries
- 1981–1996
- Co-discoverers
- 2
- Where
- Germany
Discovery timeline
1981 · Germany
Bohrium is a synthetic, radioactive element made at the GSI laboratory in Darmstadt.
1982 · Germany
Meitnerium is a synthetic, highly radioactive element. Its first detection rested on a single atom.
1984 · Germany
Hassium is a synthetic, radioactive element and a heavier relative of osmium.
1994 · Germany
Darmstadtium is a synthetic, radioactive element expected to be a heavy relative of platinum.
1994 · Germany
Roentgenium is a synthetic element predicted to be a heavier relative of gold.
1996 · Germany
Copernicium is a synthetic element in the same group as zinc, cadmium and mercury. It may be a volatile liquid or gas.
The discoveries
Earlier labs made heavy elements by firing light nuclei into heavy actinide targets, which produced very hot compound nuclei that usually broke apart. Armbruster’s group championed “cold fusion” in the nuclear sense: firing medium-heavy ions such as chromium, iron or nickel at lead or bismuth targets, so the new nucleus formed with less excess energy and had a better chance of surviving.
The key instrument was SHIP, a velocity filter that separated the rare fusion products from the enormous beam of unreacted ions in under a millionth of a second. Each new atom was then tracked through its chain of alpha decays to known nuclei, so a single event could be identified beyond doubt.
With this method the team identified bohrium in 1981, meitnerium in 1982 and hassium in 1984. In 1994 a new generation of the group, led by Sigurd Hofmann, found darmstadtium and roentgenium, and in 1996 copernicium.
Life and career
Armbruster was born in Dachau, Bavaria, studied physics in Stuttgart and Munich, and worked at the Jülich research centre before joining GSI, the heavy-ion research centre founded at Darmstadt in 1969.
He led its nuclear reactions research for decades and later became research director of the Institut Laue-Langevin in Grenoble. In later years he turned to applying heavy-ion physics to transmuting nuclear waste.
Also known for
- Pioneer of cold-fusion reactions for making superheavy elements
- Helped design the SHIP separator at GSI