Exploding Stars and Their Elusive Nuclear Reactions
The origin of the elements in the Universe is one of the big unsolved questions in science. Nuclear fusion reactions in stars are responsible for creating most of the light elements up to iron. Heavier elements are produced in a network of nuclear reactions and decays, mainly involving the capture of neutrons by unstable nuclei that only exist for fractions of a second. Therefore, it is essentially impossible to measure the majority of these rates directly in the laboratory because the unstable nuclei involved cannot be made into targets for irradiation with neutrons. An experiment performed at the National Superconducting Cyclotron Laboratory (NSCL) on the campus of Michigan State University revealed that these challenging reactions can be conquered by an indirect approach that exploits the formation of unstable nuclei in beta decay and the detection of the gamma-ray radiation liberated in the process with the SuN detector (see Figure). The experiment reported by S. N. Liddick et al., demonstrated that one can use the rare-isotope beams to constrain the elusive neutron-capture reactions indirectly. Accurate nuclear reaction rates are crucial for answering the question on the origin of the heavy elements, and the pioneering NSCL experimental approach provides a new pathway.
S. N. Liddick, A. Spyrou et al., Experimental neutron capture rate constraint far from stability, PRL 116, 242502 (2016)
And the accompanying Synopsis: http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.116.242502