<i>r</i>-process nucleosynthesis: connecting rare-isotope beam facilities with the cosmos

Horowitz, C. J.; Arcones, Almudena; Côté, Benoît; Dillmann, I.; Nazarewicz, W.; Roederer, Ian U.; Schatz, H.; Aprahamian, A.; Atanasov, D.; Bauswein, Andreas; Beers, Timothy C.; Bliss, Julia; Brodeur, M.; Clark, J. A.; Frebel, Anna; Foucart, François; Hansen, C. J.; Just, Oliver; Kankainen, A.; McLaughlin, G. C.; Kelly, James; Liddick, S. N.; Lee, Duane; Lippuner, Jonas; Martin, Dirk; Mendoza-Temis, Joel; Metzger, Brian T; Mumpower, Matthew; Perdikakis, G.; Pereira, J.; O’Shea, Brian W.; Reifarth, R.; Rogers, A. M.; Siegel, Daniel M.; Spyrou, A.; Surman, Rebecca; Tang, Xiaodong; Uesaka, T.; Wang, M.

doi:10.1088/1361-6471/ab0849

Cited by 162 publications

(114 citation statements)

References 706 publications

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“…The spectroscopic factors in Table I are normalized, arbitrarily, such that the 1960-keV = 0 transition has S ≡ 1.00. The summed strength for 1g 9/2 , 2d 5/2 , 3s 1/2 , 2d 3/2 , and 1g 7/2 are then 0.82(13), 1.02(14), 1.00, 1.00 (17), and 0.62 (12), respectively, implying that the bulk of the strength is carried by these states. The observed 1g 7/2 strength is notably lower than others, suggesting fragments of this strength lie at higher excitation energy than was probed here.…”

Section: E (Kev)mentioning

confidence: 99%

“…J π n s S 0 4 9/2 + 1g 9/2 0.82 (13) 1195 (20) (2) (5/2 + ) (2d 5/2 ) a 0.47 (9) 1600 (45) (2) (5/2 + ) (2d 5/2 ) a 0.13 (2) 1810 (20) (2) (5/2 + ) (2d 5/2 ) a 0.42 (7) 1960(30) (0) (1/2 + ) (3s 1/2 ) ≡ 1.00 2335 (20) (2) (3/2 + ) (2d 3/2 ) 1.00 (17) 2530 (20) (4) (7/2 + ) (1g 7/2 ) 0.62 (12) a The centroid of the 2d 5/2 strength lies at 1500(50) keV, with C 2 S = 1.02 (17).…”

Section: E (Kev)mentioning

confidence: 99%

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First Exploration of Neutron Shell Structure below Lead and beyond N=126

Tang¹,

Kay²,

Hoffman³

et al. 2020

Phys. Rev. Lett.

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The nuclei below lead but with more than 126 neutrons are crucial to an understanding of the astrophysical r-process in producing nuclei heavier than A ∼ 190. Despite their importance, the structure and properties of these nuclei remain experimentally untested as they are difficult to produce in nuclear reactions with stable beams. In a first exploration of the shell structure of this region, neutron excitations in 207 Hg have been probed using the neutron-adding (d,p) reaction in inverse kinematics. The radioactive beam of 206 Hg was delivered to the new ISOLDE Solenoidal Spectrometer at an energy above the Coulomb barrier. The spectroscopy of 207 Hg marks a first step in improving our understanding of the relevant structural properties of nuclei involved in a key part of the path of the r-process.The nucleus 207 Hg lies in the almost completely unexplored region of the nuclear chart below proton number 82 and just above neutron number 126, both "magic" numbers representing closed shells in the nuclear shell model [1]. The doubly-magic nucleus 208 Pb is the cornerstone of this region, a benchmark nucleus in our understanding of the single-particle foundation of nuclear structure. This region, highlighted on the nuclear chart in Fig. 1, is unique in that its single-particle structure remains unexplored.The nucleosynthesis of heavy elements via the rapid neutron-capture (r-) process path [2] crosses this region, as shown in Fig. 1. The robustness of the N = 126 neutron shell closure plays a crucial role in the nucleosynthesis of the actinides [3][4][5][6][7]. The recent observation of a neutron star merger has provided a new focus of interest [8,9], suggesting a possible astrophysical environment for r-process nucleosynthesis [10-13].Approaching the r-process path along the N = 126 isotonic chain from Pb, the binding energies (the degree to which neutrons are bound by the mean-field potential created by the decreasing number of all other nucleons) decrease, eventually crossing zero binding and becoming unbound. Near closed shells, the level density is low, so the usual statistical assumptions of many resonances participating in neutron capture is not valid, and specific nuclear-structure properties become important. Knowledge of ground-state binding energies of nuclei with N = 126 + n is important in defining the waiting point caused by the N = 126 closure, the bottleneck which is responsible for the third peak in solar system elemental abundances at nuclear mass A ∼ 195 [14]. The binding energies are critical to how the r-process evolves. The energies of ground and excited states have significant consequences for the rate at which direct s-, p-, (and possibly d-) wave neutron-capture (n,γ) reactions proceed [15][16][17]. This was discussed recently in the context of the N = 82 shell closure in Ref. [18].As zero binding is approached, the energies of s orbitals increase less rapidly than those of states with higher angular momenta [19]. This behavior has been studied for light nuclei [20,21] and, in the vicinity o...

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Section: E (Kev)mentioning

confidence: 99%

Section: E (Kev)mentioning

confidence: 99%

First Exploration of Neutron Shell Structure below Lead and beyond N=126

Tang¹,

Kay²,

Hoffman³

et al. 2020

Phys. Rev. Lett.

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“…Whether superheavy nuclei can be produced during the r -process nucleosynthesis, and whether the observed elemental abundances contain unambiguous information on the role of superheavy elements, can only be addressed through systematic reaction network calculations. On the nuclear physics side, such calculations require a consistent set of nuclear reaction rates, binding energies, beta-and gamma-decay decay rates, fission rates, and fission fragment distributions, as well as a consistent treatment of weak interactions (Horowitz et al, 2018). From an experimental point of view, further constraints will be provided by the data on neutron-rich rare isotopes from next-generation radioactive ion beam facilities.…”

Section: Perspectives and Expectationsmentioning

confidence: 99%

Colloquium : Superheavy elements: Oganesson and beyond

et al. 2019

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During the last decade, six new superheavy elements were added into the seventh period of the periodic table, with the approval of their names and symbols. This milestone was followed by proclaiming 2019 the International Year of the Periodic Table of Chemical Elements by the United Nations General Assembly. According to theory, due to their large atomic numbers, the new arrivals are expected to be qualitatively and quantitatively different from lighter species. The questions pertaining to superheavy atoms and nuclei are in the forefront of research in nuclear and atomic physics, and chemistry. This Colloquium offers a broad perspective on the field and outlines future challenges. References

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“…This scientific overlap provides an important opportunity for both FRIB and LIGO. An extensive review article on the r-process discusses many of these issues [9].…”

Section: The R-process After Gw170817mentioning

confidence: 99%

Neutron rich matter in the laboratory and in the heavens after GW170817

Horowitz

2019

Annals of Physics

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The historic observations of the neutron star merger GW170817 advanced our understanding of r-process nucleosynthesis and the equation of state (EOS) of neutron rich matter. Simple neutrino physics suggests that supernovae are not the site of the main r-process. Instead, the very red color of the kilonova associated with GW170817 shows that neutron star (NS) mergers are an important r-process site. We now need to measure the masses and beta decay half-lives of very neutron rich heavy nuclei so that we can more accurately predict the abundances of heavy elements that are produced. This can be done with new radioactive beam accelerators such as the Facility for Rare Isotope Beams (FRIB). GW170817 provided information on the deformability of NS and the equation of state of dense matter. The PREX II experiment will measure the neutron skin of 208 Pb and help constrain the low density EOS. As the sensitivity of gravitational wave detectors improve, we expect to observe many more events. We look forward to exciting advances and surprises!

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r-process nucleosynthesis: connecting rare-isotope beam facilities with the cosmos

Cited by 162 publications

References 706 publications

First Exploration of Neutron Shell Structure below Lead and beyond N=126

First Exploration of Neutron Shell Structure below Lead and beyond N=126

Colloquium : Superheavy elements: Oganesson and beyond

Neutron rich matter in the laboratory and in the heavens after GW170817

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