Pierre Marin 1927-2002
Pierre Marin died on 15 April of a heart attack, aged 74. A tireless worker, he devoted his entire life to particle physics and the physics of accelerators. By setting up and running many leading projects in these fields, he contributed greatly to major scientific breakthroughs. He was an experimentalist of imagination and rigour; a totally upright man with no inclination to compromise. He was also a committed researcher and supported a great number of generous initiatives.
He completed his PhD in nuclear physics in the 1950s at the Clarendon Laboratory in Oxford, where Hans Halban was his supervisor. Afterwards he was among those who moved with Halban to Paris to set up an experimental nuclear physics group in the Physics Laboratory at the Ecole Normale Supérieure. There, Marin built and ran two proton accelerators, where a whole series of projects was conducted, some of them led by himself. He later spent a year at CERN, working with Hyams and Backinstoss on generating an intense 7 GeV muon beam in order to measure its polarization.
In the summer of 1961, Marin travelled to Frascati to find out about the tests run there on the AdA electron-positron ring by a team of Italian physicists and engineers under Bruno Touschek. On returning to Paris from Rome, he suggested to André Blanc-Lapierre, who had by then succeeded Hans Halban as head of the Laboratoire de l'Accélérateur Linéaire (LAL), that they invite the Frascati team to LAL (together with the AdA ring, which was transported by truck to Orsay from Rome), and also to build a an e+e- collider ring with an energy of 2 ¥ 550 MeV.
Following the Frascati group's arrival at LAL, Marin joined a Franco-Italian collaboration that ran numerous beam studies on AdA which eventually led to the achievement of the first ever collisions in an electron-positron ring. At the same time, he directed the building of the ACO ring, which stored its first beam on 25 October 1965. He then supervised the first two particle physics theses based on findings from ACO. The machine paved the way for in-depth studies on r, w and F vector mesons and the first direct evidence of vacuum polarization effects in the s-channel (by analysing the e+e- Æ m+m- process at the F energy).
Marin went on to direct the building and operation of the DCI collider, with its energy of 2 ¥ 1.85 GeV, and later the Super-ACO ring, designed specifically for synchrotron radiation. With his dual background as engineer and researcher, he had total mastery over the different aspects of operating the highly innovative machines that are storage and collider rings. He also acted as a consultant for numerous machines built in France or abroad.
More recently Marin was an ardent backer of SOLEIL, the French national machine project for a third-generation synchrotron radiation source intended to serve the needs of a wide community of users. His great expertise in the ultravacuum field was also brought to bear on the VIRGO interferometer, which is designed to detect gravitational waves.
His many colleagues and friends are dismayed at his loss.
Jacques Haïssinski, LAL Orsay.
Giustina Baroni 1923-2002
Giustina Baroni died on 24 March following a disabling illness. A full professor at the University "La Sapienza" in Rome, she retired from academic and scientific activities in 1996.
Baroni was well known in the high-energy physics community. With her two degrees in chemistry and physics, she was a pioneer in the use of nuclear emulsions, from the study of the detection process with an electron microscope to the first exposures at the Pic du Midi to study the soft component of cosmic radiation. A significant highlight was the launch from the Sardinian coast of balloons carrying stacks of stripping emulsions, which reached heights of 26,000 m. This was the first of the large European collaborations, and marked a change of style in the work of our laboratories. Baroni cared especially about the few tau decays and their spin-parity analysis, thus fitting her pieces into the theta/tau puzzle. By then, the time was ripe for a switch to accelerator-produced particles.
In the emulsions returned to Rome from one of the balloon flights, an event was found with the features of a negative proton. After the successful outcome of the Berkeley experiment on antiproton production, a Berkeley-Rome collaboration was set up to expose stacks of emulsions to the antiproton beam, leading to an extensive study of antiproton interactions in emulsions. These studies were, in part, superseded a few years later when liquid hydrogen bubble chambers of large dimensions provided a large amount of clean proton-antiproton data. Another turning point came with the commissioning of CERN's proton synchrotron, and the possibility of using a pulsed magnetic field of very high intensity. There followed a search for Dirac magnetic monopoles, and the first very precise measurement of the magnetic moment of hyperons.
In 1965 Baroni became leader of the emulsion group in Rome and enthusiastically entered the "new age" of nuclear emulsions, with the so-called hybrid experiments. There, a very sensitive emulsion target was connected to electronic devices surrounding it, thus allowing special events to be selected. This was rewarded at Fermilab with the observation of a likely example of charmed particle decay produced in a neutrino beam. The Super Proton Synchrotron (SPS) at CERN was the natural site for these hybrid experiments. A powerful collaboration was set up with the other European emulsion groups, especially with the Brussels, University College London, Dublin, Turin and Bari groups. From 1975 for about 10 years, this group formed the basis for success in the search for short-lived particles. The first observations of charm and beauty mesons and baryons, and measurements of their lifetimes, were done at the SPS, in the WA17 and WA75 experiments.
Throughout this period Baroni also actively contributed to setting up a successful collaboration with Nagoya and other Japanese emulsion groups in view of the detection of tau neutrinos. Heavy-ion interactions were another field of interest, starting from carbon at the CERN Synchrocyclotron to oxygen-16 at the highest energies available at the SPS.
Baroni was a very good teacher and scientific leader, and many of her students are active in elementary particle and nuclear physics experiments. She shared her talent for physics analysis and technical developments with her collaborators with great generosity. Beyond her professional life she was a knowledgeable and refined lady, and it was always a pleasure for her colleagues to converse with her on diverse cultural and social topics. Roman archaeology was one of her greatest passions, and many friends still recall affectionately her accounts of her several trips to archaeological sites throughout the world.
Giustina Baroni will be remembered by friends, colleagues and students as a fine example of culture and humanity.