Evaluated nuclear structure and decay data for all nuclei with mass number A=201 (201Os, 201Ir, 201Pt, 201Au, 201Hg, 201Tl, 201Pb, 201Bi, 201Po, 201At, 201Rn, 201Fr, 201Ra) are presented. All available experimental data are compiled and evaluated, and best values for level and gamma-ray energies, quantum numbers, lifetimes, gamma-ray intensities and transition probabilities, as well as other nuclear properties, are recommended. Inconsistencies and discrepancies that exist in the literature are discussed. A number of computer codes (https://wwwnds. iaea.org/public/ensdf pgm/index.htm) developed by members of the NSDD network were used during the evaluation process. For example, the reported absolute gamma-ray emission probabilities and their uncertainties in various decay data sets were determined using the GABS code. The gamma-ray transition probabilities were determined using the RULER code and the corresponding uncertainties were determined using a Monte-Carlo approach. This work supersedes the earlier evaluation by F.G. Kondev (2007Ko06), published in Nuclear Data Sheets 108, 365 (2007).
The nuclear root-mean-square charge radius of Ni54 was determined with collinear laser spectroscopy to be R(Ni54)=3.737(3) fm. In conjunction with the known radius of the mirror nucleus Fe54, the difference of the charge radii was extracted as ΔRch=0.049(4) fm. Based on the correlation between ΔRch and the slope of the symmetry energy at nuclear saturation density (L), we deduced 21≤L≤88 MeV. The present result is consistent with the L from the binary neutron star merger GW170817, favoring a soft neutron matter EOS, and barely consistent with the PREX-2 result within 1σ error bands. Our result indicates the neutron-skin thickness of Ca48 as 0.15–0.21 fm.
The Accelerator Mass Spectrometry (AMS) program at the Nuclear Science Laboratory of the University of Notre Dame is focused on measurements related to galactic radioactivity and to nucleosynthesis of main stellar burning as well as the production of so called Short-Lived Radionuclides (SLRs) in the Early Solar System (ESS). The research program is based around the 11MV FN tandem accelerator and the use of the gas-filled magnet technique for isobar separation. Using a technique that evolved from radiocarbon dating, this paper presents a number of research programs that rely on the use of an 11MV tandem accelerator at the center of the AMS program.
The correct modeling of abundances requires knowledge of nuclear cross sections for a variety of neutron, charged particle and γ induced reactions. These involve targets far from stability and are therefore difficult (or currently impossible) to measure. Nuclear reaction theory provides the only way to estimate values of such cross sections. In this paper we present application of the EMPIRE reaction code to nuclear astrophysics. Recent measurements are compared to the calculated cross sections showing consistent agreement for n-, p- and α-induced reactions of strophysical relevance.
This contribution presents examples for recent experimental studies with real photons. Topics include the electric dipole response below the particle separation energy (pygmy resonance), the magnetic scissors mode in deformed nu, an analysis of low-lying electric quadrupole strength and astrophysical applications. Results of reactions induced by real photons are compared to those obtained from virtual photons (electron scattering, Coulomb excitation).
Nuclear astrophysics aims at describing nuclear processes relevant to nucleosynthesis. Such reactions can be studied by performing nuclear cross-section measurements at the relevant energy regimes. Accelerator-based experiments allow simulating nucleosynthesis in the laboratory. For specific reactions accelerator mass spectrometry (AMS) offers a powerful tool to measure cross-sections independent on half-lives of reaction products. It represents a complementary, off-line method compared to on-line methods, the latter being sensitive to prompt reaction signatures. An overview over recent experiments using AMS in nuclear astrophysics is given and for selected reactions the potential of AMS is exemplified: limitations and advantages of this method are illustrated for neutron-induced reactions on 9Be, 13C and 54Fe, leading to the long-lived AMS isotopes 10Be, 14C, and 55Fe, respectively. Measurements on 55Fe allow producing highly precise data. The potential of AMS for helping to resolve a recently observed discrepancy between observation and nucleosynthesis models relevant for our understanding of the isotopic abundances is highlighted.
The quest to comprehend how nuclear processes influence astrophysical phenomena is driving experimental and theoretical research programs worldwide. One of the main goals in nuclear astrophysics is to understand how energy is generated in stars, how elements are synthesized in stellar events and what the nature of neutron stars is. New experimental capabilities, the availability of radioactive beams and increased computational power paired with new astronomical observations have advanced the present knowledge. This review summarizes the progress in the field of nuclear astrophysics with a focus on the role of indirect methods and reactions involving beams of rare isotopes.
Nuclear reaction cross sections of short-lived nuclei are key inputs for new generation nuclear reactor simulations and for models describing the nucleosynthesis of elements. After discussing various topics of nuclear astrophysics and reactor physics where the demand of nuclear data on unstable nuclei is strong, we describe the general characteristics of the targets needed to measure the requested data. In some cases the half-life of the nucleus of interest is so short that it is not possible to produce a target and perform the measurement. However, some alternative methods have been developed that allow one to obtain neutron-induced cross sections of highly radioactive nuclei. One of these methods is the surrogate reaction technique. We explain the principle of the surrogate method and describe the characteristics of the targets used in surrogate experiments.