One of the pioneers of neutron scattering research, Hans Bjerrum Møller, passed away on January 9, 2016. Hans Bjerrum Møller devoted most of his career to Risø National Laboratory, which he joined in 1956, and where he became the head of the Physics Department in 1968, member of the laboratory management in 1982, and eventually managing director from 1988–1997. Together with visiting scientist L. Passell and chief technician W. Kofoed he designed the first triple axis spectrometer at the DR3 reactor. Together with Allan Mackintosh he was the first to study the magnon excitations in crystals of rare earth metals, which significantly broadened the then rapidly growing field of rare-earth magnetism. For these achievements they were jointly awarded the Spedding Price in 1986. He also pioneered the analytical formulations of the resolution functions for triple axis spectrometers together with Mourits Nielsen, a methodology that has been widely used in the community.
Hans Bjerrum Møller was born in 1932, went to school in Copenhagen and graduated in physics engineering from the Danish Technical University in 1956. Immediately after his graduation he joined the newly established Danish Atomic Energy Commission, and became engaged in the creation of the Risø Research Establishment. From 1958 to 1960 he worked as a visiting scientist at Brookhaven National Laboratory with V.L. Sailor and F.J. Shore on neutron cross sections, in particular on the resonances in the rare-earth nuclei. From 1962–63 he worked at the Joint European Research Center in ISPRA at the Pulsed Fast Reactor, SORA. After his return to Risø in 1963 he became leader of the solid-state physics section, and head of the Physics Department from 1968 to 1982. In this period he was a main driver for the build-up of the neutron scattering program at the DR3 reactor. This included investments in a cold neutron source, an external “cold neutron” experimental hall that included a small angle scattering facility with the support of the Danish Natural Science Research Council and the Swedish Natural Science Research Council. Hans Bjerrum Møller also promoted a visiting scientist summer program, which expanded the international network of partners and collaborators connected to the DR3 facilities. Risø became a well-known hub in the global neutron scattering community.
Hans Bjerrum Møller was instrumental in the strategy of concentrations on eight crystal spectrometers around the DR3 reactor, where Risø perfected the technology using focusing optics, filters, polarizers and advanced detectors, enabling competition with the best neutron scattering facilities in the world. At the same time the Risø program became open for outside users, and Risø became part of the European Program for Access to Large Facilities from 1980 until the reactor was closed in 2001. Besides his managerial duties Hans Bjerrum Møller continued to make important scientific contributions with Allan Mackintosh, Bente Lebech, Per Anker Lindgaard, Mourits Nielsen and Jens Gylden Houmann in the field of rare-earth metals and alloys, as well as innovative, explorative experiments in liquid crystals with Tormod Riste.
Throughout his career Hans Bjerrum Møller was a strong advocate for international research cooperation, and a promoter of international sharing of work and facilities. One of his platforms for these efforts was the Magnetism Commission of the International Union of Pure and Applied Physics, where he served as the secretary (1972–1978). Others were his memberships of the steering committee of the European Fusion programs (1980–1988); of the Euratom Scientic and Technical Committee (1995–2001); of the board of directors for the EU Joint Research Center, JRC, (1992–2001); and of EUREKA's High Level Group (1998–2003).
Hans Bjerrum Møller was married to Inger Johanne Thorshaug, whom he met on the trip back by boat from the fist visit to Brookhaven. They had four children of which the oldest son died tragically at a young age. Hans and his family also had to mourn the early death of Inger Johanne in 1995. He enjoyed his retirement years in a house with splendid view of the Roskilde fjord and later on he moved closer to children and grand children near a lake in the north of Copenhagen. He was a trusted friend and a devoted father.