Tributes Roland Barloutaud (1925-2000) Roland Barloutaud passed away on 23 January. A graduate of the Sorbonne, Barloutaud began his career working on measurements of weakly radioactive materials before moving on to Saclay in 1951. In 1960 he joined the High Energy Physics Laboratory at Saclay, and from 1962 took part in many collaborations using CERN's 80 cm and 2 m bubble chambers. In around 1977 he led the analysis of photographs from the Mirabelle bubble chamber at Serpukhov as part of a CERN-France-Soviet Union collaboration. In the 1980s Barloutaud turned his attention to the Fréjus experiment, sparking an interest in particle astrophysics that fascinated him until the end of his life. John Blewett (1910-2000) Accelerator pioneer John Blewett died on 7 April, a few days short of his 90th birthday. Born and educated in Toronto, he completed his PhD at Princeton in 1936. After a postdoctoral year at the Cavendish Laboratory in Cambridge, Blewett worked at General Electric's Research Laboratory. There, he calculated that a beam of circu- lating electrons should lose energy through radiation. Synchrotron radiation was duly observed in 1947. Meanwhile, Blewett had moved to Brookhaven, where he contributed to the Cosmotron, the Alternating Gradient Synchrotron and the Light Source, as well as working for the Isabelle collider. From 1953 until 1954, at the invitation of Odd Dahl, Blewett worked with the small group designing CERN's Proton Synchrotron. In 1993 he was awarded the American Physical Society's Robert R. Wilson Prize. Louis Leprince-Ringuet (1901-2000) CERN pioneer Louis Leprince-Ringuet died on 23 December. Born in Alès, Leprince-Ringuet graduated from the Ecole Polytechnique. In 1933, he joined Pierre Auger on a ship sailing from Hamburg to Buenos Aires with an array of particle detectors on board to study the variation of cosmic ray intensity with latitude in order to ascertain whether cosmic rays were charged or neutral. Leprince-Ringuet was a powerful advocate for the establishment of CERN, and his efforts led to two French bubble chambers being installed as the Proton Synchrotron was commis- sioned in 1959. This eventually led to the Gargamelle chamber and its 1973 discovery of the neutral current. He was vice-chairman of CERN’s Scientific Policy Committee from its inception, and its chairman from 1964 - 66. He was elected to the Académie française in 1966. Giuliano Preparata (1942-2000) Italian theoretician Giuliano Preparata died on 24 April. After graduating in 1964, Preparata joined Raoul Gatto's group in Florence. Later he produced excellent work in the US on symmetries, current algebra, and on the field the- ory approach to particle physics. After returning to Italy, he soon came to CERN as a staff member. He was later Professor of Theoretical Physics at Bari and Milan. With time, Preparata became critical of many steps in the con- struction of the Standard Model and of some parts of its foundations. His interests then shifted increasingly to dif- ferent subjects such as nuclear physics, superconductivity, cold fusion, and quantum gravity. He was at CERN for the last time in January, when Remo Ruffini gave a presentation on their joint work on a possible mechanism for the production of gamma-ray bursts. © Sciences Frontières John Thresher (1929-2000) 35 Former CERN research director John Thresher died suddenly on 25 August. After obtaining his bachelor's degree from Cape Town and his DPhil from Oxford, he started his career at the UK Atomic Energy Research Establishment, Harwell. He then spent two years at Berkeley before returning to the UK in 1963, joining what is now the Rutherford Appleton Laboratory (RAL). Thresher's association with CERN began in 1968 when his group worked on a CP viola- tion experiment at the Proton Synchrotron. In 1975 he became head of RAL's High Energy Physics Division and in 1981 associate director for particle physics. From 1986 to 1991, Thresher was CERN Director of research with responsibility for the new LEP experimental programme. He retired in 1992. Tom Ypsilantis (1928-2000) Detector virtuoso Tom Ypsilantis died on 16 August. Born in 1928, he studied physics at Berkeley under Emilio Segrè. Together with Owen Chamberlain and Clyde Wiegand, he joined the historic 1955 experiment at the new Bevatron that first observed antiprotons. After a pioneer role in teaching modern physics in Greece, he came to CERN in 1968 and met Jacques Séguinot. This was the origin of a lifelong friendship and a series of innovative par- ticle detectors. Together they proposed the technique that became the Ring Imaging Cherenkov (RICH) counter. More recently they worked on noble-liquid calorimetry and on a very large water neutrino detector based on the fast-RICH technique. The "AquaRICH" was described by Ypsilantis as "a Superkamiokande with spectacles". His authority in the field led to him becoming editor of Nuclear Instruments and Methods in 1995..