Recent measurements of pre-equilibrium neutron and proton transverse emission from 112,124 Sn+ 112,124 Sn reactions at 50 MeV/A have been completed at the National Superconducting Cyclotron Laboratory. Free nucleon transverse emission ratios are compared to those of A=3 mirror nuclei. Comparisons are made to BUU transport calculations and conclusions concerning the density dependence of the asymmetry term of the nuclear equation-of-state at sub-nuclear densities are made. The double-ratio of neutron-proton ratios between two reactions is employed as a means of reducing first-order Coulomb effects and detector efficiency effects. Comparison to BUU model predictions indicate a density dependence of the asymmetry energy that is closer to a form in which the asymmety energy increases as the square root of the density for the density region studied. A coalescent-invariant analysis is introduced as a means of reducing suggested difficulties with cluster emission in total nucleon emission. Future experimentation is presented.PACS numbers: 25.70.Mn,21.65.+f,26.62.+c The nuclear symmetry energy increases the masses of nuclei with very different neutron and proton concentrations and limits the neutron concentration and maximum neutron number N of any element. In the interior regions of neutron stars, where neutrons may comprise over 90% of the matter, the symmetry energy may contribute the bulk of the pressure supporting the star [1]. The nuclear equation-of-state at densities of 0.5≤ ρ ρ0 ≤10 (where ρ 0 is the nuclear saturation density) governs many of the neutron star macroscopic properties, including radius, moment of inertia, core structure [2], cooling rates, and the possible collapse of a neutron star into a black hole [3,4,5].Constraints on the symmetry energy at sub-saturation density have been obtained from measurements of the diffusion of neutrons and protons between nuclei of different asymmetry δ = (N-Z)/(N+Z) in peripheral collisions [6,7]. (Here N and Z are the relevant neutron and proton number of the nuclei.) Measurements of nuclear masses, isovector collective excitations and neutron skin measurements may also provide constraints at densities less than ρ 0 . Nevertheless, the density dependence of the symmetry energy is not known well enough to constrain the relevant neutron star properties. Using an alternative approach to improve present constraints, new measurements of the ratios of neutron and proton spectra in central heavy ion collisions are presented and compared to transport theory calculations. These calculations display a strong sensitivity to the density dependence of the symmetry energy, from which additional contraints may ultimately be derived [8] Using proton and neutron densities calculated from the non-linear relativistic mean-field theories as inputs, the dynamics of nucleon-nucleon collisions are calcuated. These calculations utilize nucleonic mean field potentials corresponding to an equation-of-state that can be expressed (at zero temperature) in terms of the mean energy of a nuc...

This is an exciting time for the study of r-process nucleosynthesis. Recently, a neutron star merger GW170817 was observed in extraordinary detail with gravitational waves and electromagnetic radiation from radio to γ rays. The very red color of the associated kilonova suggests that neutron star mergers are an important r-process site. Astrophysical simulations of neutron star mergers and core collapse supernovae are making rapid progress. Detection of both, electron neutrinos and antineutrinos from the next galactic supernova will constrain the composition of neutrino-driven winds and provide unique nucleosynthesis information. Finally FRIB and other rare-isotope beam facilities will soon have dramatic new capabilities to synthesize many neutron-rich nuclei that are involved in the r-process. The new capabilities can significantly improve our understanding of the r-process and likely resolve one of the main outstanding problems in classical nuclear astrophysics.However, to make best use of the new experimental capabilities and to fully interpret the results, a great deal of infrastructure is needed in many related areas of astrophysics, astronomy, and nuclear theory. We will place these experiments in context by discussing astrophysical simulations and observations of r-process sites, observations of stellar abundances, galactic chemical evolution, and nuclear theory for the structure and reactions of very neutron-rich nuclei. This review paper was initiated at a three-week International Collaborations in Nuclear Theory program in June 2016 where we explored promising r-process experiments and discussed their likely impact, and their astrophysical, astronomical, and nuclear theory context.

We have measured fragment cross-sections of projectile fragmentation reactions using primary beams of 40 Ca, 48 Ca, 58 Ni, and 64 Ni at 140 MeV/nucleon on 9 Be and 181 Ta targets. The cross-sections were obtained by integrating the momentum distributions of isotopes with Z 5 measured in the A1900 fragment separator. We compare the extracted cross-sections to the predictions of the empirical parametrization of fragmentation cross-sections (EPAX).

The results of a study of the beta decays of three proton-rich nuclei with Tz = -2, namely 48 Fe, 52 Ni and 56 Zn, produced in an experiment carried out at GANIL, are reported. In all three cases we have extracted the half-lives and the total β-delayed proton emission branching ratios. We have measured the individual β-delayed protons and β-delayed γ rays and the branching ratios of the corresponding levels. Decay schemes have been determined for the three nuclei, and new energy levels are identified in the daughter nuclei. Competition between β-delayed protons and γ rays is observed in the de-excitation of the T = 2 Isobaric Analogue States in all three cases. Absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. In addition, we discuss in detail the data analysis taking as a test case 56 Zn, where the exotic β-delayed γ-proton decay has been observed.