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Benjamin Ailes photo
Faculty profile
Joseph Cerny’s legacy
RADIOACTIVE D E C AY
Chemistry professor
Joseph Cerny served as
Vice Chancellor for
Research and Dean of
the Graduate Division
from 1985 through
2000.
Joseph Cerny has made seminal discoveries in radioactive decay and the properties of
nuclei far from the stable isotopes, served in some of the top administrative posts on
campus, and educated a new generation of nuclear scientists. He has also worked to
better the lives and jobs of postdoctoral fellows and is currently assisting the soon-toopen
UC Merced campus in maintaining the high faculty quality of the University of
California. Not a quiet career at all. “And with hardly a dull moment,” notes Cerny.
Studying nuclear decay
A nuclear chemist, Cerny and his graduate
students and postdocs have devoted a lot of
experimental effort toward discovering new modes of
radioactive decay and the properties of highly unstable
nuclei. Radioactivity itself was discovered in 1896 by Henri
Becquerel when a sample of a uranium compound kept in
the dark was found to expose photographic plates. The
mysterious radiations were later shown to be helium
nuclei (alpha particles), electrons (beta particles) and
photons (gamma rays). Radioactivity is the conversion of
an unstable nucleus of an atom to relatively more stable
ones and ultimately to one of the 265 known stable
isotopes. Research on radioactive nuclei, primarily using
particle accelerators such as the cyclotron or using nuclear
reactors, has led to the discovery of some 2,600 artificially
produced isotopes, many with highly unusual neutron to
proton ratios. This field remains of intense interest, since
nuclear theorists have predicted that three to four thousand
additional radioactive nuclei should exist (however
fleetingly).
Cerny has discovered numerous radioactive isotopes
and a new mode of radioactive decay, and he has worked
out new pathways in complex radioactive decay. He was
honored with the E. O. Lawrence Award by the U.S. Atomic
Energy Commission in 1974 for the discovery of proton
emission as the fourth fundamental mode of radioactive
decay and for his investigation of the limits of nuclear stability
of a number of light elements. The theory for proton
radioactivity parallels that for alpha-particle radioactivity,
but is a simpler process and gives more direct evidence of
the basic nuclear structure of the decaying nuclide.
In an influential paper in 1983, Cerny and his collaborators
reported a complex new type of radioactive decay that
occurs in extremely proton-rich nuclei. This decay is initiated
by beta-particle emission from the parent nuclide,
but the daughter state is so highly excited that it decays by
sequentially emitting two protons, which can be detected
in coincidence. Currently Cerny is using the 88-inch
cyclotron at LBNL to look for direct evidence of an even
rarer process: the simultaneous emission of two protons,
which was first indirectly observed in France in 2002.
“Studies of nuclei very far from the stable isotopes continue
to reveal highly unusual nuclear radioactivity,” noted Cerny.
BEARS project
He has recently been instrumental in establishing the
BEARS project at LBNL—the Berkeley Experiments with
Accelerated Radioactive Species (BEARS). By utilizing two
cyclotrons, his group developed a light-ion, proton-rich
radioactive beam capability that provides experimenters
with the opportunity to perform a wide range of measure-
8 BERKELEY COLLEGE OF CHEMISTRY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .