Olli V. Lounasmaa
August 2002

Academician Olli Viktor L o u n a s m a a, born on August 20, 1930, earned his Bachelor's Degree in physics from the University of Helsinki in 1953 and his D. Phil. Degree from the University of Oxford in 1958. His thesis was on the thermodynamic properties of fluid 4He. After two years of research on liquid 4He at the University of Turku in Finland he became, in 1960, Resident Research Associate of the Argonne National Laboratory near Chicago. There he built a 3He refrigerator and completed an extensive series of measurements on the nuclear heat capacity of rare earth metals. During this period he also did some research on liquid 4He near the l-transition.

In 1965 Lounasmaa returned to Finland. He was appointed Professor of Technical Physics at the Helsinki University of Technology where he founded the Low Temperature Laboratory (LTL) and became its director. Since then he has specialized in research at milli-, micro-, nano- and even picokelvin temperatures. In 1970 he was appointed Professor of the Academy of Finland. Government rules forced him to retire in January 1996. Three refrigerators, employing adiabatic nuclear demagnetization techniques for cooling, have been operating under Lounasmaa's directorship in the Low Temperature Laboratory. In two of them, rotating 3He can be investigated between 0.4 and 3 mK: extensive NMR, superfluid flow, ion mobility, ultrasonic, and optical measurements have been carried out on vortices in rotating 3He-A and 3He-B. The first demonstration of superfluidity in 3He was made and eight different vortices, including a vortex sheet, were discovered.

The third cryostat, intended for research on nuclear cooperative phenomena in metals, has two nuclear cooling stages working in series. This apparatus and its modifications have held many world's low temperature records, currently 100 pK in the nuclear spin system of rhodium. The same cryostat has produced "record-high" negative spin temperatures, first in silver and then in rhodium (750 pK). Three antiferromagnetic phases have been discovered in copper and antiferromagnetic and ferromagnetic phases in silver.

Another double nuclear refrigerator, constructed in Helsinki for neutron diffraction studies at nanokelvin temperatures, was operating first at the Risø National Laboratory in Denmark in 1985 90 and then at the Hahn-Meitner-Institute in Berlin in 1991 97; this was a joint Danish-Finnish-German research effort, partially financed by the European Community's SCIENCE program. Nuclear ordering in copper at T > 0 was studied in Risø and investigated in silver in Berlin. The LTL is also participating in the Spin-Muon Collaboration at CERN by being responsible for the construction of a very powerful dilution refrigerator. Much work has also been done by Lounasmaa and his students on the Mössbauer effect, on thermometry below 1 K, and on the use of SQUIDs for low temperature and brain research. Large scale uses of superconductivity have been investigated as well, including the construction of a 0.17 T superconducting solenoid for whole-body MR imaging. A 1.5 T magnet, 2 m long and with an 0.8 m bore, was completed in 1988.

A magnetically shielded room was built in 1980 to the Low Temperature Laboratory. With this facility, Lounasmaa's attention was partly turned to measurements of the weak magnetic signals produced by the human brain; in fact, neuromagnetism did become his secondary field of interest. After several smaller instruments, a SQUID magnetometer with 24 simultaneously operating channels was put to use in 1989. A 122-SQUID device, which covers the whole head and was the first instrument in this category, was operational in the Low Temperature Laboratory since the summer of 1992. Many extensive series of magnetoencephalographic (MEG) experiments, such as studies of basic neurophysiology, localizing epileptic foci, investigating cognitive processes, and studies of signal processing in the human brain have been carried out. In 1998, a 306-channel device was commissioned.

In 1977 Lounasmaa worked for a year at Saclay near Paris. He has also spent 1 to 2 months as Visiting Professor in the United States, Japan, India, Germany and Denmark. During the Academic Year 1982 83 he pursued research first in the University of California at Berkeley and later in the New York University. Most of 1996 he was working in the Hahn-Meitner-Institut in Berlin. Since the beginning of 1997 he came back in his old laboratory in Finland as an Academy Professor Emeritus.

Prof. Lounasmaa is the author of 250 scientific papers, including a book entitled Experimental Principles and Methods below 1 K. He has given almost 300 seminar or colloquium talks at low temperature laboratories throughout the world and attended about 100 international conferences, presenting over 40 plenary or invited papers. He has also given 20 series of lectures abroad, many of them at international schools of physics. Lounasmaa has supervised the Ph.D. theses of 48 students and written expert's opinions on the qualifications of candidates for many professorships in Finland and abroad. While he was the director of the LTL, a total of 58 Ph.D. theses were approved. In 1994 96 Lounasmaa was the Coordinator of two Large-Scale Facilities, BIRCH in neuro- and cardiomagnetism and ULTI in ultralow temperature physics, established by the European Union's Human Capital and Mobility Program. He has also been active in science policy in Finland having served, for example, in 1980 and in 1984 as Chairman of Ministry of Education's working groups on basic research. At the Ministry's request he prepared in 1995 a 70-page evaluation of the departments of mathematics, physics, chemistry, and computer sciences in Finnish universities.

In 1965 Lounasmaa was elected to the Finnish Academy of Technical Sciences (Medal in 1999), in 1969 to the Finnish Academy of Sciences and Letters (President in 1992), in 1974 to the Royal Swedish Academy of Sciences (Foreign Member), in 1976 to the Societas Scientiarum Fennica (Silver Medal in 2000) and to Honorary Membership of the Indian Cryogenics Council. In 1989 Lounasmaa was elected to Academia Europaea. In 1986 he became Fellow of the American Physical Society and in 1998 Foreign Associate (= Member) of the US National Academy of Sciences. He is also past President of the Finnish Physical Society and its Honorary Member since 1990.

In 1969 Lounasmaa received the Th. Homén Prize of Societas Scientiarum Fennica, in 1973 the Emil Aaltonen Foundation Prize, in 1978 the Finnish Cultural Foundation Prize, and in 1984 the Fritz London Memorial Award, presented at the 17th International Conference on Low Temperature Physics. In 1987 he was, together with three of his colleagues, given the Award for the Advancement of European Science by the Körber-Stiftung of Hamburg. In 1990 he received the Finnish Government's Inventors Prize and in 1991 the Professor of the Year title. In 1990 he was promoted to the Degree of Doctor of Philosophy honoris causa by the University of Helsinki in connection with the University's 350-year celebrations. In 1992, he received the Degree of Doctor of Technology honoris causa by the Tampere University of Technology and in 1998 by the Helsinki University of Technology. In 2000 he became Doctor of Medicine honoris causa of the University of Helsinki.

Lounasmaa is Commander 1st Class of the Order of the White Rose of Finland and Commander of the Order of the Lion of Finland. In 1993 he was honored by the Forschungspreis of the Alexander von Humboldt-Stiftung of Germany and in 1994 he was awarded the Wihuri International Prize. In 1995 he received the Finnish Government's Decoration for 30 Years of Service, the first Kapitza Gold Medal, established by the Russian Academy of Sciences on the occasion of Pjotr Kapitza's 100th birthday, and the Italgas Prize in physics, donated by the Italgas Company and awarded in collaboration with the Academy of Sciences of Torino. The same year he also received the Espoo medal and the bronze medal of the Academy of Finland. In 1996 he was honored by the Mendelssohn Prize and Gold Medal awarded by the International Cryogenic Engineering Committee. In 1997 Olli Lounasmaa obtained the title of Academician from the President of Finland; a total of 12 Finnish scientists can simultaneously hold this title. His portrait, painted by the Dutch artist Carla Rodenberg, was unveiled at the Helsinki University of Technology in 1997.

Prof. Lounasmaa has participated extensively in international collaboration among low temperature physicists. He has been President of the Commission on Cryophysics of the International Institute of Refrigeration and Chairman and Member of the Very Low Temperature Physics Commission of the International Union of Pure and Applied Physics; he has also been a member of the International Cryogenic Engineering Committee. For four years he served on the Executive Committee of the European Physical Society. In 1992 99 he was member of Comité International des Poids et Mesures. He was in 1975 President of the 14th International Conference on Low Temperature Physics (LT-14) and in 1984 President of the 10th International Cryogenic Engineering Conference (ICEC-10). He was President of the 7th General Conference of the European Physical Society (EPS-7), held in Helsinki in 1987. He has organized six smaller international conferences and several winter schools with foreign participation. He has been a member of the International Committees of over 20 scientific conferences held abroad. He has been member of the Editorial Boards of many scientific journals; currently Europhysics Letters and, most importantly, Proceedings of the National Academy of Sciences of the USA.

Lounasmaa has spent most of his time since October, 1999 in writing his comprehensive memoirs, which will be submitted to a Finnish publisher before the end of 2002.

Lounasmaa is married and has two daughters and four granddaughters. He has made extensive travels with his family to South-Africa and Zimbabwe, to Israel, India, Beijing, Brazil, New York, Australia and Singapore, and to Germany, Holland and France.