202 FRIB Graduate Brochure

Bradley Sherrill
University Distinguished Professor of Physics,
FRIB Scientific Director
Keywords: Rare Isotope Production, Ion Optics, Drip Line Search
Experimental Nuclear Physics
About
• BA, Physics, Coe College, 1980
• MS, Physics, Michigan State University, 1982
• PhD, Physics, Michigan State University, 1985
• Joined the laboratory in January 1985
• sherrill@frib.msu.edu
Research
Approximately 270 isotopes are found naturally. However,
many more isotopes, nearly 7,000 in total, can be
produced by particle accelerators or in nuclear reactors.
These isotopes are radioactive and spontaneously decay
to more stable forms, and I work to produce and separate
new and interesting ones.
There are several reasons why a latent demand exists
within the scientific community for new, rare isotopes.
One is that the properties of particular isotopes often
hold the key to understanding some aspect of nuclear
science. Another is that the rate of certain nuclear
reactions involving rare isotopes can be important for
modeling astronomical objects, such as supernovae. Yet
another is that the properties of atomic nuclei can be
used to test nature’s fundamental symmetries by searches
for deviations from known symmetry laws. Finally, the
production of isotopes benefits many branches of science
and medicine as the isotopes can be used as sensitive
probes of biological or physical processes.
isotopes and work to better understand the best ways to
produce any given isotope. We use and work to improve
the modeling code LISE++, which involves interesting
problems in computational science.
Research in this area includes study and design of
magnetic ion optical devices. learning the various nuclear
production mechanisms and improving models to
describe them. This background allows one to contribute
to science by making new isotopes, but also prepares one
for a broad range of careers in academia, government
(e.g. national security), and industry.
Selected Publications
NSCL and FRIB at Michigan State University: Nuclear
science at the limits of stability; A. Gade and B.M. Sherrill,
Physica Scripta Volume: 91 (2016) 053003
Design of the Advanced Rare Isotope Separator ARIS at
FRIB; M. Hausmann, et. al., Nucl. Instruments and Methods
B, on-line (2013)
Location of the Neutron Dripline at Fluorine And Neon
Isotopes; Ahn DS, et al., Phys. Rev. Lett. 123 (2019) 212501;
Discovery of 60Ca and Implications For the Stability of
70Ca, O. B. Tarasov, et al., Phys.
Rev. Lett. 121 (2018) 022501
The tools for production and separation of rare
isotopes gives scientists access to designer nuclei with
characteristics that can be adjusted to the research need.
For example, super-heavy isotopes of light elements,
such as lithium, have a size nearly five times the size of
a normal lithium nucleus. The existence of such nuclei
allows researchers to study the interaction of neutrons
in nearly pure neutron matter, similar to what exists in
neutron stars.
For production of new isotopes, the approach that I have
helped develop is called in-flight separation; where a
heavy ion, such as a uranium nucleus, is broken up at high
energy. This produces a cocktail beam of fragments that
are filtered by a downstream system of magnets called
a fragment separator. Our current research is focused
on preparing for experiments at FRIB where we hope
to discover nearly 1,000 new isotopes. Simultaneously,
we will study the nuclear reactions that produce new
The rich variety of nuclei is indicated by the depiction of
three isotopes 4 He, 11 Li, and 220 Ra overlaid on the chart of
nuclides where black squares indicate the combination
of neutrons and protons that result in stable isotopes,
yellow those produced so far, and green those that might
exist. Nuclei like 11 Li have very different characteristics,
such as a diffuse surface of neutron matter, than do
normal nuclei.
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