Gopal Shenoy was born on 26 January 1940 in Kasargod, India, and passed away on 29 November 2017 in Naperville, Illinois. He received his BSc, MSc, and PhD from the Institute of Science in Mumbai, India. His career at Argonne National Laboratory spanned 43 years, starting in 1967. He had a major impact, first as a bench scientist in the Mössbauer Spectroscopy Laboratory, then as a group leader for synchrotron radiation research in the Materials Science Division, then as a founding father of the Advanced Photon Source. He led in formulating the need for an advanced synchrotron radiation source for the nation, and then in raising Argonne’s capacity to compete for and ultimately bring the Advanced Photon Source to Argonne.
Gopal began his career at Argonne in the Solid State Science Division, working with Michael Kalvius at the Mössbauer Laboratory. Together with Bobby Dunlap, they carried out fundamental work on actinide and lanthanide chemistry and physics. Taking advantage of reactor facilities at Argonne, they carried out pioneering work on magnetism and superconductivity in uranium, neptunium, ytterbium, gadolinium, erbium, and europium compounds. Their work later helped Argonne attract new generations of scientists to develop nuclear resonant scattering. Gopal was the first researcher to enter the 200+ club of the Mössbauer Effect Data Center. The impact of his studies is quite visible our current understanding of electronic structure of heavy fermions, ternary superconductors, Chevrel phase compounds, and high-performance magnets.
By the mid 1980s Gopal’s scientific interest moved to nanocluster physics. Together with Pedro Montano and researchers from Fritz-Haber Institute, Gopal pioneered the use of EXAFS spectroscopy in studying the atomic arrangements in pure metal nanoclusters embedded in a noble gas matrix. Their work on gold, silver, copper, and iron nanoclusters is still extensively cited. Gopal led the effort to form the X-11 Participating Research Team at Brookhaven’s National Synchrotron Light Source. Similarly, a soft-x-ray spectroscopy beamline was acquired at the Synchrotron Research Center in Wisconsin. The time was right for Argonne to plan for a new major scientific research facility.
Gopal seized on this historic opportunity and, as early as 1982, pushed for an insertion-device based synchrotron light source. He formed a research group in synchrotron radiation and installed the most advanced computational codes at the time for undulator radiation calculations. His enthusiasm was matched by that of Yanglai Cho, and working together they developed a low-emittance lattice storage ring design with 35 undulator sources. It was Gopal (together with James Viccaro) who fully optimized undulator designs to cover the entire energy range of interest in the x-ray regime. The synchrotron radiation community was excited by this work, and 350 participants attended the first users meeting for an unfunded, unnamed synchrotron source held at Argonne in 1986. This was a turning point for Argonne National Laboratory in its successful bid to build and operate the Advanced Photon Source.
Starting in 1987, Gopal’s attention, and that of David Moncton, the first Director of the photon source, was directed to detailed design and construction as well as to creating a healthy national scientific user community As x-ray division director Gopal organized collaborative access teams to fund and operate beamlines. Gopal understood and appreciated the importance of physical infrastructure needed for the design and construction of the x-ray beamlines, and for addressing technologically challenging issues such as the handling of high-heat load from the intense x-ray beams and developing critical x-ray optics components.
Later, Gopal played a major role in putting together the science case for Linac Coherent Light Source, the world’s first x-ray free electron laser, at Stanford, and remained actively involved in guiding the early scientific proposals. He served on many international scientific advisory committees of synchrotron radiation facilities in the world, including the Australian Synchrotron, the European Synchrotron Radiation Facility, the European XFEL, and Japan’s SPring-8.
In the 2000s, after leaving his APS management position, Gopal turned to novel experimental development issues. His constant enthusiasm led to the first successful fast mechanical chopper for nuclear-resonant x-ray scattering studies. His work on MEMS-based cantilevers to manipulate the time structure of light sources promises to be very useful in time-resolved studies at current and future light sources.
Gopal always had an eye on the future. As early as 1995, he was working on laser-based x-ray light sources. The first demonstration of the self-amplified spontaneous emission principle, with laboratory leaders such as Moncton, Efim Gluskin, John Galayda, Michael Borland, and Stephen Milton, paved the way for x-ray free-electron lasers in the world today.
Gopal Shenoy proved time and again that he could connect to young researchers, support their work, fire their enthusiasm, challenge their ideas, and encourage them to publish their work. He will be greatly missed.
