http://www.sciencenews.org | November 20, 2021 25Icing on the cake
Along with studying atomic nuclei at
extremes and exploring nuclear physics
of the stars, scientists hope to use FRIB to
make progress in two other key areas.Harvesting
useful nuclei
Scientists plan to
collect isotopes
produced in
FRIB for societal
applications.
In medicine,
for example, certain isotopes, such as
terbium-149, can be used for radiation
treatment or medical imaging.
When this isotope of the rare earth metal
terbium decays, it can emit alpha particles
(helium nuclei) that can kill cancer cells. Its
half-life of 4.1 hours is in a sweet spot: fast
enough to have an effect — it doesn’t take
hundreds of years to decay — but not so
fast that it’s gone within seconds, before it
can do its work.Testing laws
of nature
Scientists plan
to check certain
physics rules,
for example,
the idea that
matter and
antimatter behave as mirror images.
Certain hypothetical physics effects could
cause particles to flout this rule, and that
could help explain why there’s more matter
than antimatter in the universe.
Effects that could make matter and
antimatter behave differently might also
cause electric charge in atoms to separate,
with slightly more positive charge on one
side of the atom and more negative on the
other. In most atoms, this separation may
be too tiny to measure. But in radium-225,
which has a pear-shaped nucleus, the effect
would be stronger, as the nucleus’ asymme-
try should enhance the asymmetry of the
atom’s charge. — Emily ConoverTb
terbium65
Ra
radium88
iron, have been synthesized,” she says.
Many of the elements around us — and in
us — formed within stars. As large stars age, they
fuse progressively larger atomic nuclei together
in their cores, creating elements farther along the
periodic table — oxygen, carbon, neon and oth-
ers. But the process halts at iron. The rest of the
elements must be born another way.
A process called the rapid neutron capture
process, or r-process, is responsible for many
of those other elements found in nature. In the
r-process, atomic nuclei quickly soak up neutrons
and bulk up to large masses. The neutronfest is
interspersed with radioactive decays that form
new elements. The sighting of two neutron stars
merging in 2017 revealed that such collisions are
one place where the r-process occurs (SN: 11/11/17,
p. 6). But scientists suspect it might happen in other
cosmic locales as well (SN: 6/8/19, p. 10).
Cizewski and colleagues are studying an
abbreviated form of the r-process that might
thrive in supernovas, which may not have enough
oomph for the full r-process. The team has zeroed
in on germanium-80, which plays a pivotal role in
the weak r-process. Physicists want to know how
likely this nucleus is to capture another neutron
to become germanium-81. At FRIB, Cizewski will
slam a beam of germanium-80 into deuterium,
which has one proton and one neutron in its
nucleus. Knowing how often germanium-80
captures the neutron will help scientists nail down
the neutron-slurping chain of the weak r-process,
wherever it might crop up.A Borromean bent
Like the interlinked Borromean rings, different
facets of nuclear physics are closely entwined,
from mysteries of the cosmos to the inner work-
ings of nuclei. The exotic nuclei that FRIB cooks
up could also allow physicists to tap into the very
bedrock of physics by testing certain fundamental
laws of nature. And there’s a practical side to the
facility as well. Scientists could collect some of
the isotopes FRIB produces for use in medical
procedures, for example.
Physicists are ready for surprises. “Every time
we build such a facility, new discoveries come
and breakthroughs in science come,” Nazarewicz
says. Like the 1980s discovery of lithium-11’s
Borromean nucleus, scientists may find some-
thing totally unexpected. sExplore more
FROM TOP: MICHIGAN STATE UNIV.; ADAM BURROWS/PRINCETON UNIV., JOE INSLEY AND SILVIO RIZZI/ARGONNE NATIONAL LABs Facility for Rare Isotope Beams. frib.msu.edu/
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