Progress in Particle and Nuclear Physics 107 (2019) 109–166 Contents lists available at ScienceDirect Progress in Particle and Nuclear Physics journal homepage: www.elsevier.com/locate/ppnp Review Current status of r-process nucleosynthesis ∗ T. Kajino a,b,c, W. Aoki a, A.B. Balantekin a,d, R. Diehl e,f, M.A. Famiano a,g, , G.J. Mathews a,h a National Astronomical Observatory of Japan, Mitaka, Tokyo, Japan b University of Tokyo, Tokyo, Japan c Beihang University, Beijing, China d University of Wisconsin, Madison 53706, USA e Max Planck Institut für Extraterrestrische Physik, Garching, Germany f Technical University of Munich, Germany g Western Michigan University, USA h University of Notre Dame, USA article info a b s t r a c t Article history: The rapid neutron capture process (r process) is believed to be responsible for about Available online 6 March 2019 half of the production of the elements heavier than iron and contributes to abundances Keywords: of some lighter nuclides as well. A universal pattern of r-process element abundances nucleosynthesis is observed in some metal-poor stars of the Galactic halo. This suggests that a well- r process regulated combination of astrophysical conditions and nuclear physics conspires to astrophysics theory produce such a universal abundance pattern. The search for the astrophysical site nuclear experiment for r-process nucleosynthesis has stimulated interdisciplinary research for more than astronomical observation six decades. There is currently much enthusiasm surrounding evidence for r-process nucleosynthesis in binary neutron star mergers in the multi-wavelength follow-up ob- servations of kilonova/gravitational-wave GRB170807A/GW170817. Nevertheless, there remain questions as to the contribution over the history of the Galaxy to the current solar-system r-process abundances from other sites such as neutrino-driven winds or magnetohydrodynamical ejection of material from core-collapse supernovae. In this review we highlight some current issues surrounding the nuclear physics input, as- tronomical observations, galactic chemical evolution, and theoretical simulations of r-process astrophysical environments with the goal of outlining a path toward resolving the remaining mysteries of the r process. ' 2019 Elsevier B.V. All rights reserved. Contents 1. Introduction............................................................................................................................................................................................. 111 2. Nuclear theory ........................................................................................................................................................................................ 113 2.1. Theoretical neutron capture rates ........................................................................................................................................... 113 2.2. Theoretical nuclear masses....................................................................................................................................................... 113 2.3. Theoretical nuclear structure ................................................................................................................................................... 114 2.4. Theoretical β-decay rates ......................................................................................................................................................... 114 2.5. β-delayed neutron emission .................................................................................................................................................... 115 ∗ Corresponding author. E-mail addresses: [email protected] (T. Kajino), [email protected] (W. Aoki), [email protected] (A.B. Balantekin), [email protected] (R. Diehl), [email protected] (M.A. Famiano), [email protected] (G.J. Mathews). https://doi.org/10.1016/j.ppnp.2019.02.008 0146-6410/' 2019 Elsevier B.V. All rights reserved. 110 T. Kajino, W. Aoki, A.B. Balantekin et al. / Progress in Particle and Nuclear Physics 107 (2019) 109–166 2.6. Fission barriers and fission fragment distribution................................................................................................................. 115 2.7. Neutrino physics ........................................................................................................................................................................ 116 3. Experimental nuclear data .................................................................................................................................................................... 116 3.1. Nuclear masses........................................................................................................................................................................... 117 3.1.1. Mass measurement compilations and evaluations ................................................................................................ 117 3.1.2. Trap measurements ................................................................................................................................................... 118 3.1.3. TOF Measurements..................................................................................................................................................... 119 3.1.4. Storage rings ............................................................................................................................................................... 121 3.1.5. Other similar systems................................................................................................................................................ 123 3.2. β-decay rates and spectroscopy .............................................................................................................................................. 123 3.2.1. RIKEN ........................................................................................................................................................................... 123 3.2.2. CERN ISOLDE............................................................................................................................................................... 124 3.2.3. ANL/CARIBU ................................................................................................................................................................ 125 3.2.4. NSCL............................................................................................................................................................................. 125 3.2.5. GSI................................................................................................................................................................................ 125 3.2.6. Jyväskylä...................................................................................................................................................................... 126 3.2.7. ORNL ............................................................................................................................................................................ 126 3.2.8. Charge exchange ........................................................................................................................................................ 126 3.3. β-delayed neutron emission .................................................................................................................................................... 126 3.4. Fission barriers and distributions ............................................................................................................................................ 127 3.5. β-delayed fission ....................................................................................................................................................................... 127 3.6. Neutron capture rates ............................................................................................................................................................... 128 3.6.1. Direct Measurements................................................................................................................................................. 128 3.6.2. Surrogate Reactions.................................................................................................................................................... 128 3.6.3. Coulomb Dissociation ................................................................................................................................................ 128 3.6.4. β-Oslo Technique ....................................................................................................................................................... 129 3.6.5. Other facilities and techniques................................................................................................................................. 129 3.7. Nuclear structure studies.......................................................................................................................................................... 129 3.7.1. Neutron separation energies and shell closures..................................................................................................... 129 3.7.2. Isomers .......................................................................................................................................................................