Experimental nuclear physics

Nuclear scientists pursue answers to fundamental questions about how atoms exist, how the different kinds of atoms are formed in the universe, and what atoms are made of. Answers come by colliding atomic nuclei at half the speed of light to in a billionth of a trillionth of one second create isotopes of the elements that do not normally exist on Earth. Particle accelerators like FRIB allow scientists to explore beyond what was previously known. Specially designed equipment and state-of-the-art computers make the study of the produced isotopes and how they interact possible.

Exploring exotic nuclei

Research at FRIB concentrates on the study of rare isotopes, one of the current frontiers in nuclear science. Compared to the more familiar atomic nuclei found in the atoms of objects on Earth, rare isotopes are exotic with a large excesses of either protons or neutrons. They are very unstable and decay quickly, sometimes within fractions of a second. Experimental groups use the world-leading capabilities of FRIB to produce rare isotopes through fragmentation of accelerated stable isotopes that break when they strike a target nucleus. The exotic fragments are transported to the experimental stations within hundreds of nanoseconds, where a wide range of experiments are carried out using state-of-the-art research equipment.

Types of experiments

Some experiments determine the existence of a particular isotope for the very first time. Others stop the nuclei to study their decay or to measure their mass. Some experiments have the exotic isotopes bombard another target and study the ensuing nuclear reactions revealing information about the internal structure of the nucleus or the behavior of nuclear matter during the extreme temperatures and densities. With a vast new landscape of isotopes available for study, FRIB will reveal many surprising properties of rare isotopes. It will guide researchers to a comprehensive picture of atomic nuclei.

At the laboratory, theorists are working closely with experimentalists to interpret these results. They use exotic nuclei as probes to uncover hidden aspects of the nuclear force that normally lies hidden. Understanding this force and building a nuclear theory that can predict its properties is one of the goals in nuclear science. Rare isotopes also play an important role in astrophysics. They are created in stellar explosions such as X-ray bursts and supernovae and are believed to exist inside neutron stars. Often, the decays of exotic nuclei are intermediate steps in the astrophysical processes that created the elements in nature. Many FRIB groups work at the intersection of nuclear physics and astrophysics to address open questions raised by astronomical observations. Such questions concern the origin of the elements, the nature of stellar explosions, and the properties of neutron stars.

The quantum realm of the atomic nucleus likely holds other secrets. What particles and forces of nature are at play is a key question. The properties of some rare isotopes are suspected to hold the key to discovering answers and show the way to new physics beyond the Standard Model, which among other reasons is needed to understand the matter-antimatter asymmetry in the universe. Often, such studies involve ion and atom trapping and high-precision laser spectroscopy.