Discussion journal of the Mössbauer Community

["Nagy, Denes Lajos" <nagy.denes AT wigner.mta.hu>]

Dr. Gopal K. Shenoy, the distinguished member of the international 
Mössbauer community and one of the founders of the Advanced Photon Source 
at Argonne passed away on 29 November 2017. Our deepest sympathies go to 
Gopal's family and colleagues.

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Dr. Gopal K. Shenoy – An Appreciation

Dr. Gopal K. Shenoy's career Argonne National Laboratory started in 1967. 
Altogether he spent 43 years at the Laboratory. During this time, 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 current 
X-ray Science Division. He played a leading role in formulating the need 
for an advanced synchrotron radiation source for the nation, and then in 
raising Argonne's capacity to compete for this light source, culminating 
in bringing the Advanced Photon Source (APS) to Argonne.

Gopal started his career at Argonne in the Solid State Science Division, 
working with M. Kalvius at the Mössbauer Laboratory. Together with Bobby 
Dunlap, who later became the Director of Materials Science Division, they 
carried out fundamental work on actinide and lanthanide chemistry and 
physics. Taking full advantage of reactor facilities at Argonne, they 
carried out pioneering work on magnetism and superconductivity in uranium, 
neptunium, ytterbium, gadolinium, erbium, europium compounds. At the time, 
Argonne's reputation as the premier Mössbauer laboratory in the world was 
well established, which later on helped the Laboratory attract new 
generations of scientists to develop excellence in 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 
in the development of electronic structure of heavy fermions, ternary 
superconductors, Chevrel phase compounds, and high-performance magnets.

By the mid-1980's Dr. Shenoy's scientific interest moved to nanocluster 
physics. Together with Dr. Pedro Montano, and working with researchers 
from Fritz-Haber Institute, Gopal pioneered the use of EXAFS spectroscopy 
in studying the atomic arrangements in pure metal nanoclusters embedded in 
noble gas matrix. Their work on gold, silver, copper, and iron 
nanoclusters are still being extensively cited today. This work was 
coincident with the formation of the X-11 Participating Research Team at 
the National Synchrotron Light Source at Brookhaven National Laboratory, 
with Gopal leading the Argonne effort. Similarly, a soft-x-ray 
spectroscopy beamline was acquired at the Aladdin ring at the Synchrotron 
Research Center in Wisconsin, and J. C. Campuzano developed the pioneering 
ARPES experiments here.

With the work on EXAFS coinciding with the development of the Argonne 
Intense Pulsed Neutron Source, the time was right for Argonne to bid for a 
major scientific research facility. Shenoy seized on this historic 
opportunity and as early as 1982, he was in the forefront for pushing 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. His enthusiasm 
was matched by that of Dr. Yanglai Cho, and working together, they came up 
with a low-emittance lattice storage ring design with extensive undulator 
sources. It was Shenoy, (together with James Viccaro) who demonstrated 
that 7 GeV would be the right energy for a single undulator to cover the 
entire energy range of interest in the x-ray regime. The entire 
synchrotron radiation community felt the intensity of his early work, such 
that 350 participants attended the first User 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.

During the 1990's, Gopal's attention, and that of Dr. David Moncton, the 
first Director of the APS, was given to completion of the construction of 
the APS, as well as to creating a healthy scientific user community, 
particularly in the Midwest. His intense effort led to the formation of 
Collaborative Access Teams, which provided additional funding for the 
construction of beamlines. Gopal, together with Dennis Mills, Deming Shu, 
and Tuncer Kuzay managed to create all the infrastructure needed for the 
design and construction of the experimental beamlines, and for addressing 
technologically challenging issues such as the handling of high-heat load 
from the intense x-ray beams.

Gopal played a major role in putting together the science case for Linac 
Coherent Light Source at Stanford, and remained actively involved in 
guiding the early scientific proposals. He served on many scientific 
advisory committees of major hard x-ray synchrotron radiation facilities 
in the world, including the Australian Synchrotron, the European 
Synchrotron Radiation Facility, the European XFEL, and SPring-8.

In the 2000's, after leaving his position in the top management of the 
APS, Gopal turned his attention to novel experimental development issues. 
His never-changing enthusiasm led to first successful demonstration of a 
fast mechanical chopper in nuclear-resonant 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.

During his entire tenure at Argonne, Gopal Shenoy managed to have an eye 
on the future. As early as 1995, he was active in developing 
free-electron-based light sources. The first successful demonstration of 
the self-amplified spontaneous emission principle, a joint work with 
laboratory leaders such as Moncton, Efim Gluskin, John Galayda, Michael 
Borland, and Stephen Milton, paved the way for free-electron lasers in the 
world today.

Gopal Shenoy proved time and again that he could connect to young 
researchers, support their work, light their enthusiasm, challenge their 
ideas, and encourage them to publish their work.

Ercan Alp
Senior Physicist,
X-ray Science Division
Argonne National Laboratory

https://www1.aps.anl.gov/APS-Science-Highlight/2017/gopal-k-shenoy-a-founde
r-of-the-aps-passed-away