0000000001034602
AUTHOR
A. Spyrou
Low-lying level structure of Cu56 and its implications for the rp process
The low-lying energy levels of proton-rich Cu56 have been extracted using in-beam γ-ray spectroscopy with the state-of-the-art γ-ray tracking array GRETINA in conjunction with the S800 spectrograph at the National Superconducting Cyclotron Laboratory at Michigan State University. Excited states in Cu56 serve as resonances in the Ni55(p,γ)Cu56 reaction, which is a part of the rp process in type-I x-ray bursts. To resolve existing ambiguities in the reaction Q value, a more localized isobaric multiplet mass equation (IMME) fit is used, resulting in Q=639±82 keV. We derive the first experimentally constrained thermonuclear reaction rate for Ni55(p,γ)Cu56. We find that, with this new rate, the …
A systematic study of proton capture reactions in the SeSb region at energies relevant to the p process
Abstract A systematic investigation of (p,γ) cross sections of nuclei from Se to Sb is presented. In-beam cross section measurements were carried out at E p = 1.4–5 MeV by using an array of 4 HPGe detectors of 100% relative efficiency shielded with BGO crystals. The S factors obtained are compared with the predictions of the statistical model code MOST.
Plunger Lifetime Measurements in 102Pd
Recently, an intense experimental effort has been devoted to the search of empirical proofs of critical‐point symmetries in nuclear structure. These symmetries describe shape‐phase transitions and provide parameter‐free predictions (up to over‐all scale factors) for excitation spectra and B(E2) values. This contribution reports on recent plunger‐lifetime measurements ON 102Pd carried out at LNL, Legnaro, with the Cologne plunger apparatus coupled to the GASP spectrometer and using the 92Zr(13C,3n)102Pd reaction at 48 MeV. According to the results of our measurements, 102Pd is so far the best known paradigm of the E(5) critical‐point symmetry.
Horizons: Nuclear Astrophysics in the 2020s and Beyond
Nuclear astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated.We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field…
Systematic measurements of proton- and alpha-capture cross sections relevant to the modelling of the p process
Several in-beam cross section measurements of proton- as well as α -capture reactions in the Se-Sb region have been carried out to obtain global input parameters for Hauser-Feshbach (HF) calculations. In total, 20 (p, γ ) and 7 ( α , γ ) reactions were measured. We compare some of these results with Hauser-Feshbach calculations using various optical model potentials and nuclear level densities.
FRIB and the GW170817 Kilonova
In July 2018 an FRIB Theory Alliance program was held on the implications of GW170817 and its associated kilonova for r-process nucleosynthesis. Topics of discussion included the astrophysical and nuclear physics uncertainties in the interpretation of the GW170817 kilonova, what we can learn about the astrophysical site or sites of the r process from this event, and the advances in nuclear experiment and theory most crucial to pursue in light of the new data. Here we compile a selection of scientific contributions to the workshop, broadly representative of progress in r-process studies since the GW170817 event.
Novel Techniques for Constraining Neutron-capture Rates relevant to Heavy-element Nucleosynthesis
In this contribution we discuss new experimental approaches to indirectly provide information on neutron-capture rates relevant to the $r$-process. In particular, we focus on applications of the Oslo method to extract fundamental nuclear properties for reaction-rate calculations: the nuclear level density and the $\gamma$ strength function. Two methods are discussed in detail, the Oslo method in inverse kinematics and the beta-Oslo method. These methods present a first step towards constraining neutron-capture rates of importance to the $r$-process.
Experimental Neutron Capture Rate Constraint Far from Stability
Nuclear reactions where an exotic nucleus captures a neutron are critical for a wide variety of applications, from energy production and national security, to astrophysical processes, and nucleosynthesis. Neutron capture rates are well constrained near stable isotopes where experimental data are available; however, moving far from the valley of stability, uncertainties grow by orders of magnitude. This is due to the complete lack of experimental constraints, as the direct measurement of a neutron-capture reaction on a short-lived nucleus is extremely challenging. Here, we report on the first experimental extraction of a neutron capture reaction rate on ^{69}Ni, a nucleus that is five neutro…
Determining therp-Process Flow throughNi56: Resonances inCu57(p,γ)Zn58Identified with GRETINA
An approach is presented to experimentally constrain previously unreachable (p, γ) reaction rates on nuclei far from stability in the astrophysical rp process. Energies of all critical resonances in the (57)Cu(p,γ)(58)Zn reaction are deduced by populating states in (58)Zn with a (d, n) reaction in inverse kinematics at 75 MeV/u, and detecting γ-ray-recoil coincidences with the state-of-the-art γ-ray tracking array GRETINA and the S800 spectrograph at the National Superconducting Cyclotron Laboratory. The results reduce the uncertainty in the (57)Cu(p,γ) reaction rate by several orders of magnitude. The effective lifetime of (56)Ni, an important waiting point in the rp process in x-ray burst…
Proton and alpha-particle capture reactions at sub-Coulomb energies relevant to the p process
Several cross-section measurements of proton as well as α-particle capture reactions in the Se–Sb region have been carried out at sub-Coulomb energies with the aim to obtain global input parameters for Hauser–Feshbach (HF) calculations. Some of the results are compared with HF calculations using various optical model potentials and nuclear level densities.
FRIB and the GW170817 Kilonova
In July 2018 an FRIB Theory Alliance program was held on the implications of GW170817 and its associated kilonova for r-process nucleosynthesis. Topics of discussion included the astrophysical and nuclear physics uncertainties in the interpretation of the GW170817 kilonova, what we can learn about the astrophysical site or sites of the r process from this event, and the advances in nuclear experiment and theory most crucial to pursue in light of the new data. Here we compile a selection of scientific contributions to the workshop, broadly representative of progress in r-process studies since the GW170817 event.