X-ray free-electron lasers and the exploration of matter at the angstrom-femtosecond scale

Claudio Pellegrini is a physicist recognized for his work on electron and photon beams physics, coherent X-ray sources, particle accelerators and their applications, novel lasers/ plasmas accelerators. He is particularly known for his work on collective effects and self-organization phenomena. Understanding these phenomena, and how to control and utilize them, was critically important for electron-positron colliders development for high-energy physics, leading to the standard model of elementary particles, and for the development of X-ray free-electron lasers, which opened a new exploration window for atomic and molecular science at the Angstrom-femtosecond space and time resolution. Pellegrini was born in Rome, Italy, where he grew up. He graduated from the University of Rome in 1958 and received the “Libera Docenza” in 1965. He worked at Frascati National Laboratory in Italy and Brookhaven National Laboratory in Upton, New York. He was Fellow at CERN. He is a Distinguished Professor Emeritus at the University of California, Los Angeles and is now working at the SLAC National Accelerator Laboratory. He is a Fellow of the American Physical Society (APS) and has been Chair of the APS Division of Physics of Beams. He received a Fulbright Fellowship, the APS R.R. Robert Wilson Prize, the Free-electron Laser Prize and the Enrico Fermi Presidential Award. He is a member of the National Academies of Sciences.

Claudio Pellegrini is mainly interested in multi body, collective and self-organization phenomena in particle beams and their applications to particle colliders for high energy physics and the generation of coherent X-ray radiation with free-electron lasers. X-ray lasers in the Angstrom region using population inversion in the inner atomic levels are not possible because of their short lifetime. Pellegrini proposed an alternative approach using free-electron lasers (FELs) based on self-amplified spontaneous emission (SASE). He lead the work to establish the theoretical foundation of X-ray SASE FELs and the experimental work at UCLA demonstrating for the first time the validity of the theoretical models, measuring very large gain and the statistical properties of the radiation. His work lead to the development of X-ray FELs in the USA and worldwide, opening for the first time the exploration of atomic and molecular science at the simultaneous Angstrom-femtosecond space and time resolution. X-ray FELs are producing breakthrough new science in chemistry, physics and biology. He is continuing his work to extend the capabilities of X-ray FELs to ultra-high peak power and attosecond pulse duration.