Matey Dragomirov Mateev (1940–2010)

Matey Mateev, a leading Bulgarian scientist and eminent theoretical physicist, perished together with his wife Rumiana Mateeva in a car accident near Sofia on 25 July. A teacher of generations of physicists and an organizer of scientific activities, he was dedicated to international collaboration in science.

Mateev was born in Sofia on 10 April 1940, the son of a medical doctor in a family that was part of the old Bulgarian intelligentsia. Graduating at Sofia University, "St. Kliment Ohridski", in 1963 he became an assistant professor of theoretical physics in the university’s faculty of physics. International collaboration played an important role in his career from the start. Early in his professional life Mateev won a one-year grant to work at the newly founded International Centre for Theoretical Physics in Trieste. Later, from 1971, he worked for a decade in the Laboratory of Theoretical Physics at JINR in Dubna, where he gained his PhD and a Doctor of Science degree (for a dissertation on the concept of fundamental length in high-energy physics). In 1983 he became full professor at Sofia University, where he taught for 25 years. In 2003 he was elected a member of the Bulgarian Academy of Sciences.

International collaboration has also been a vital element in the development of Bulgarian physics. As an established scientist in his own right, it was natural for Mateev to use his influence – as a minister of national education in the years 1990–1991, and later – to promote international collaboration with Bulgarian physicists for the benefit of future generations. He was, in particular, instrumental in Bulgaria’s admission to CERN as a member state in 1999 and he represented his country on the CERN Council in the period 1999–2000. He was also a member of the Scientific Council of JINR from 1993 and chair of the Bulgarian Union of Physicists from 2001.

Mateev was involved in many other activities, participating in work ranging from high-temperature superconductivity to crystal growth. In recent years he wrote, together with Alexander Donkov who passed away a year ago, the first advanced textbook on quantum mechanics in Bulgarian. He continued until the last day of his life his work with Vladimir Kadyshevsky from JINR on a quantum field theory with fundamental length.

Matey, known as Mag by those close to him, was a kind and warm person. He naturally attracted people and had good friends in many countries around the world. We shall miss him.

His colleagues and friends.

Alessandro G Ruggiero 1940–2010

Alessandro Ruggiero, senior physicist in the Collider-Accelerator Department at Brookhaven National Laboratory passed away at his home on 26 June after a long battle with cancer.

Alessandro Ruggiero’s story is one of the search for new ideas and improvements to particle accelerators, which sent him to live in many locations around the globe. Sandro, as he was known by his friends and colleagues, was born on 10 April 1940 in Rome. He studied at the Institute of Physics of the University of Rome and gained his PhD in 1964, based on work done at the electron synchrotron at the Laboratory Nazionali di Frascati. His first move took him to CERN in 1966 on a two-year fellowship to work on the CERN Electron Storage Accelerator Ring and the Intersecting Storage Rings. Together with Andrew Sessler and Vittorio Vaccaro he developed a systematic description of collective beam instabilities in terms of stability charts and coupling impedances, which had a lasting influence on accelerator theory. The time at CERN stimulated his interest in all aspects of accelerator physics, a field he never left.

In 1970 Sandro accepted an appointment at Fermilab and the US subsequently became his new home and he became a citizen in 1980. The period from 1970 to 1984 at Fermilab allowed him to establish himself as a first-class theoretical accelerator physicist. As a member of the theory group, he not only studied beam-intensity effects in accelerators and storage rings in general terms, but also solved known problems. He is credited with having made major contributions to the concept and design of the two-ring antiproton source for the Tevatron, especially the stochastic cooling method in the Accumulator and the design of the Debuncher. In 1985, Sandro accepted a post as senior physicist at the Argonne National Laboratory. He was attracted by the proposal to build the Argonne Wakefield Accelerator Facility. At the same time, he successfully led an inter-laboratory group to improve the performance of ALADDIN, the 1 GeV synchrotron-radiation facility in Wisconsin.

Sandro had previously shown interest in ISABELLE, the precursor to the Relativistic Heavy Ion Collider (RHIC) at Brookhaven, by providing the beam-stability analysis at the workshop held in 1975. So, when Brookhaven’s future direction as an accelerator laboratory was being discussed after the ISABELLE project was terminated, he was invited to explore the options for a heavy-ion collider. In 1987 he went to Brookhaven as senior physicist with tenure and stayed there until his untimely death. He was lured by the possibility of influencing the design and construction of the proposed RHIC, which he could do as head of the Accelerator Physics Group. He applied his expertise of beam dynamics and instabilities to the various components of RHIC – from the Tandem via the Booster and the Alternating Gradient Synchrotron to the collider itself – resulting in a stable, high-intensity machine.

Sandro was always driven by the search for challenges, as well as their implementation in new projects. He participated in the study and design of the Brookhaven-designed Accumulator ring for the Spallation Neutron Source at Oak Ridge National Laboratory. He became involved in proton radiography for the Stockpile Stewardship programme of the US Department of Energy (DOE) and a facility for nuclear waste transmutation in conjunction with Lawrence Livermore National Laboratory. He conceived and promoted a circular RF quadrupole as an alternative to a ring of conventional magnets in collaboration with the Accelerator Physics Group at the University of Naples. He participated in the study of a non-scaling, fixed-field, alternating-gradient accelerator as a proton driver for isotope production, a muon collider or a neutrino factory. He studied and produced papers on the formation of crystal beams. Although drawn mainly to new concepts and proposals, he was equally active in the measurements of the beam at RHIC and the interpretation of its instabilities and performance limitations.

Sandro was an eminent accelerator physicist, respected by his peers worldwide. He was an adjunct professor of physics at the University of Wisconsin in Madison and taught accelerator physics to young students at the US Particle Accelerator School. He had more than 200 publications to his credit, organized accelerator conferences and was the editor of several workshop proceedings. He was a member of many review committees for the DOE and for foreign projects. His outstanding contributions to physics were recognized when he was elected a fellow of the American Physics Society for "contributions to accelerator theory, including instabilities and nonlinear dynamics, to accelerator complex designs notably the Antiproton Source and the Relativistic Heavy Ion Collider and to accelerator architecture investigations of spallation neutron sources".

With Sandro’s death, the accelerator community has lost a true innovator and a lively personality. He will be missed by his friends and colleagues, at Brookhaven and around the world. He is survived by his wife Amalia (Liucci) Ruggiero, children Sara and Filippo, and grandchildren.

Harald Hahn, with input from Thomas Roser, Vittorio Vaccaro and Claudio Pelligrini.