How Quantum Mechanics Cracked the Nuclear Code

Free public lecture by physicist Charles W. Clark scheduled for March 15 at UC Riverside

RIVERSIDE, Calif. — At dawn on Thanksgiving Day of 1931, not one person in the world had a clear understanding of the essential facts of nuclear structure.  But then deuterium — the heavy stable isotope of hydrogen and a bound state of a proton and a neutron — was discovered later that day using elementary quantum mechanics and atomic spectroscopy, and provided a key clue in solving the puzzle.

The six months following deuterium’s discovery were among the most productive in the history of science, with many of the most important basic facts of nuclear structure being suddenly assembled then and rapidly exploited thereafter.

Charles W. Clark

Charles W. Clark is the co-director of the Joint Quantum Institute at the National Institute of Standards and Technology and the University of Maryland, College Park. Photo credit: National Institute of Standards and Technology.

How the pieces of the mysterious puzzle of the structure of the atomic nucleus fell quickly into place within a matter of months, about exactly 80 years ago, due to two experiments is the subject of a talk at the University of California, Riverside on Thursday, March 15, by theoretical atomic and molecular physicist Charles W. Clark.

Titled “Photon, atom and neutron: how quantum mechanics cracked the nuclear code,” the talk will take place at 3:30 p.m. in Room 138 in Winston Chung Hall.  The free lecture is open to the public.  Parking costs $6.

“The two experiments are rather easy to describe and understand, and to a degree that makes them seem rather obvious in hindsight,” said Clark, the co-director of the Joint Quantum Institute at the National Institute of Standards and Technology (NIST) and the University of Maryland, College Park.  “They touched off a spark that took nuclear science from a status of essentially no fundamental knowledge, to building atomic bombs, within thirteen years.”

Clark explained that precise measurements of a few spectral lines of atomic hydrogen revealed the existence of deuterium, a previously unknown substance.

“Once its existence was known, it was soon being produced in industrial quantities,” he said. “It had been hiding in the open!”

The discovery of deuterium was recognized by a Nobel Prize in chemistry in 1934 (to Harold Urey).  Eight years later, the first nuclear reactor went into operation.  Three years after that the atom bomb was demonstrated.  On the 21st anniversary of deuterium, the first hydrogen bomb was detonated.

“We are now in the 80th anniversary of this remarkable period,” Clark said.

He received his doctoral degree in physics from the University of Chicago in 1979. His research interests include the dynamics of ultracold atoms and atomic and molecular phenomena on surfaces, in condensed matter, and in nuclear reactions. His research activities are also in quantum information and telecommunications.

A career civil servant, Clark received the Distinguished Presidential Rank Award in 2007, a R&D 100 Award in 2008, the Gold Medal from the U.S. Department of Commerce, and the Government Computer News Award for Information Technology Achievement in 2011. His numerous honors include being named a fellow of NIST, the Washington Academy of Sciences, the American Association for the Advancement of Science, the Institute of Physics, the Optical Society of America, and the American Physical Society.  He is the recipient of the Archie Mahan Prize from the Optical Society of America as well as the Edward U. Condon Award from NIST.

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