Quasi-elastic-scattering and transfer reaction cross-section measurements were made for the 7 Be + 27 Al system at E lab = 17, 19, and 21 MeV in the angular range θ c.m. = 12 • −43 • . An optical model (OM) analysis of the quasi-elastic scattering data was carried out. The fusion cross sections were derived at these energies by subtraction of the integrated transfer cross sections from the reaction cross sections obtained from the fits to quasi-elastic-scattering data. These fusion cross sections were found to be consistent with those obtained from the coupled-channels calculations. Elastic scattering and fusion cross sections were measured for the 7 Li + 27 Al system at E lab = 10, 13, 16, 19, and 24 MeV. For elastic scattering the angular coverages were in the θ lab = 12 • −72 • range and for fusion the α-evaporation spectra from the compound nucleus were measured in the angular range θ lab = 52 • −132 • (142 • at 10 MeV). The elastic-scattering angular distributions were subjected to OM analysis. The α-evaporation spectra were reproduced with the statistical model calculations, and the fusion cross sections were extracted from them. The fusion cross sections were also extracted by subtraction of the integrated inelastic-scattering cross sections from the reaction cross sections obtained from the OM fits to the elastic-scattering data, and these fusion data were found to be consistent. The CCDEF calculations describe these data quite well. A comparison of the fusion data for the 7 Be + 27 Al and 7 Li + 27 Al systems shows a similar and consistent behavior.

We have studied the f decay of the Tz = -1 , f y2 shell nuclei 54Ni, 50Fe, 46Cr, and 42Ti produced in fragmentation reactions. The proton separation energies in the daughter T. = 0 nuclei are relatively large («4-5 MeV) so studies of the y rays are essential. The experiments were performed at GSI as part of the Stopped-beam campaign with the RISING setup consisting of 15 Euroball Cluster Ge detectors. From the newly obtained high precision /1-decay half-lives, excitation energies, and f branching ratios, we were able to extract Fermi and Gamow-Teller transition strengths in these f) decays. With these improved results it was possible to compare in detail the Gamow-Teller (GT) transition strengths observed in beta decay including a sensitivity limit with the strengths of the Tz = +1 to Tz = 0 transitions derived from high resolution (3He,f) reactions on the mirror target nuclei at RCNP, Osaka. The accumulated B(GT) strength obtained from both experiments looks very similar although the charge exchange reaction provides information on a broader energy range. Using the "merged analysis" one can obtain a full picture of the £(GT) over the full Qp range. Looking at the individual transitions some differences are observed, especially for the weak transitions. Their possible origins are discussed.

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This Letter reports on a systematic study of β-decay half-lives of neutron-rich nuclei around doubly magic 208 Pb. The lifetimes of the 126-neutron shell isotone 204 Pt and the neighboring [200][201][202] Ir, 203 Pt, 204 Au are presented together with other 19 half-lives measured during the "stopped beam" campaign of the rare isotope investigations at GSI collaboration. The results constrain the main nuclear theories used in calculations of r-process nucleosynthesis. Predictions based on a statistical macroscopic description of the first-forbidden β strength reveal significant deviations for most of the nuclei with N < 126. In contrast, theories including a fully microscopic treatment of allowed and first-forbidden transitions reproduce more satisfactorily the trend in the measured half-lives for the nuclei in this region, where the r-process pathway passes through during β decay back to stability. DOI: 10.1103/PhysRevLett.113.022702 PACS numbers: 25.70.Mn, 23.40.-s, 26.30.Hj, 27.80.+w In very hot, neutron-rich stellar environments, the r process of nucleosynthesis is ignited in a series of rapid neutron captures on seed nuclei of the Fe group, thus creating very exotic neutron-rich nuclei that β decay back to stability around the neutron shell closures with N ¼ 50, 82, and 126. In these "waiting-point" regions, matter is accumulated at masses A ∼ 80, 130, and 195, thus creating the so-called first, second, and third r-abundance peaks. These basic features of the r process were established more than half a century ago [1]. However, how the heavy nuclei from Ni to U are synthesized is one of the major unanswered questions of modern physics because of the large uncertainties in the path, time scale, and astrophysical conditions for the rapid neutron capture process to develop [2]. Observational constraints such as the elemental abundances in metal-poor stars or in solar system material help to determine astronomical sites where it might occur [3,4]. Concurrently, β-decay properties of very exotic nuclei near the path, such as β half-lives, are critical in determining the observed abundances [5]. Since many of the r-process progenitors cannot be accessed with present radioactive ion beam facilities, estimates of r-process nucleosynthesis generally rely upon predictions of stateof-the-art nuclear models, based on the properties of nuclei far from stability [6][7][8][9][10][11]. But at extreme values of isospin, theoretical predictions may be biased by microscopic structural effects that modify the shape of the β-strength function, such as nuclear shell quenching or deformation [12,13]. Until now, such theories have only been tested with information on β decay around the first two waiting points

Evaporation residue cross sections and spin distributions have been measured for 200 Pb compound nucleus formed in 16 O+ 184 W reaction at the laboratory beam energies of 84, 92, 100, 108, 116, and 120 MeV. The evaporation residues have been selected using the recoil mass spectrometer, HIRA and detected using a 2D position sensitive silicon detector. The evaporation residue spin distributions have been measured by detecting gamma rays with 14 element BGO multiplicity filter. Measured evaporation residue cross sections and spin distributions are compared with the values predicted by a standard statistical model code. Comparison shows that, in the energy region studied, the nuclear viscosity parameter γ = 3 is required to explain total evaporation residue cross sections and evaporation residue spin distributions.