Session B3: Science with Intense Beams of Rare Isotopes: On the way to FRIB

Nuclear Astrophysics and Rare Isotopes

A new generation of rare isotope facilities will help define the nuclear physics of exotic astrophysical environments. The data -- nuclear masses and weak rates -- will reduce the microphysics uncertainties in astrophysical models, helping modelers gain better control over other parameters. I discuss several examples, with special emphasis on the r-process, where quantities of interest include the freezeout radius, dynamic timescale, and flavor physics affecting the ejecta of core-collapse supernovae.   

Francis M. Pipkin Award Talk: Simple Atom, Extreme Nucleus: Laser Trapping and Probing of Helium-8

Helium-8 ($^{8}$He) is the most neutron-rich matter to have been synthesized on the Earth: it consists of two protons and six neutrons, and remains stable for an average of 0.2 seconds. It is often viewed as a $^{4}$He core with four additional neutrons orbiting at a relatively large distance, forming a halo. Because of its intriguing properties, $^{8}$He has the potential to reveal new aspects of the fundamental forces among the constituent nucleons. We have recently succeeded in laser trapping and cooling this exotic helium isotope, and have performed precision laser spectroscopy on individual trapped atoms. Based on the atomic frequency differences measured along the isotope chain $^{4}$He -- $^{6}$He -- $^{8}$He, the nuclear charge radius of $^{8}$He has now been determined for the first time. Comparing this result with the values predicted by a number of nuclear structure calculations, we test theoretical understanding of the nuclear forces in the extremely neutron-rich environment. Moreover, this method of capturing and probing atoms of rare isotopes is also applied to experiments that test fundamental symmetries and to applications of ultrasensitive trace analysis.   

Promise and Preparations of FRIB for Nuclear Astrophysics

The promise of FRIB for nuclear astrophysics will be discussed, and tentative plans for the facility implementation will be given. The current state of experiments in producing and studying new isotopes important for explosive scenarios in nuclear astrophysics will be reviewed and this status used to extrapolate to what might be expected with a more powerful FRIB facility. For example, the current state of delineating the limits of nuclei will be presented and prospects for how this might be extended at FRIB described. Finally some of the challenges that need to be addressed prior to FRIB operation, such as how we might model the fission of very neutron rich nuclei and measure neutron and proton radii in exotic isotopes, will be presented.