Total reaction cross sections from 141^{141}141Pr(α\alpha,α\alpha)141^{141}Pr elastic scattering and α\alpha-induced reaction cross sections at low energies

Elastic scattering data for $^{141}$Pr($\alpha$,$\alpha$)$^{141}$Pr have been analyzed to derive a new energy-dependent local potential for the $^{141}$Pr-$\alpha$ system. This potential is used successfully to predict the cross section of the $^{141}$Pr($\alpha$,n)$^{144}$Pm reaction at low energies where new experimental data have become available very recently. Contrary to various global potentials, this new potential is able to reproduce simultaneously elastic scattering data around and above the Coulomb barrier and reaction data below the Coulomb barrier for the $^{141}$Pr-$\alpha$ system. Reasons for the partial failure of the global potentials are explained by intrinsic properties of the scattering matrix and their variation with energy. The new local potential may become the basis for the construction of a new global $\alpha$-nucleus potential.Comment: 12 pages, 8 figures, Phys. Rev. C, accepte

Challenges in nucleosynthesis of trans-iron elements

© 2014 Author(s).. All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.Nucleosynthesis beyond Fe poses additional challenges not encountered when studying astrophysical processes involving light nuclei. Astrophysical sites and conditions are not well known for some of the processes involved. On the nuclear physics side, different approaches are required, both in theory and experiment. The main differences and most important considerations are presented for a selection of nucleosynthesis processes and reactions, specifically the s-, r-, γ-, and νp-processes. Among the discussed issues are uncertainties in sites and production conditions, the difference between laboratory and stellar rates, reaction mechanisms, important transitions, thermal population of excited states, and uncertainty estimates for stellar rates. The utility and limitations of indirect experimental approaches are also addressed. The presentation should not be viewed as confining the discussed problems to the specific processes. The intention is to generally introduce the concepts and possible pitfalls along with some examples. Similar problems may apply to further astrophysical processes involving nuclei from the Fe region upward and/or at high plasma temperatures. The framework and strategies presented here are intended to aid the conception of future experimental and theoretical approaches.Peer reviewe

70Ge(p,gamma)71As and 76Ge(p,n)76As cross sections for the astrophysical p process: sensitivity of the optical proton potential at low energies

The cross sections of the 70Ge(p,gamma)71As and 76Ge(p,n)76As reactions have been measured with the activation method in the Gamow window for the astrophysical p process. The experiments were carried out at the Van de Graaff and cyclotron accelerators of ATOMKI. The cross sections have been derived by measuring the decay gamma-radiation of the reaction products. The results are compared to the predictions of Hauser-Feshbach statistical model calculations using the code NON-SMOKER. Good agreement between theoretical and experimental S factors is found. Based on the new data, modifications of the optical potential used for low-energy protons are discussed.Comment: Accepted for publication in Phys. Rev.

Reaction Rate Sensitivity of the gamma-Process Path

The location of the (gamma,p)/(gamma,n) and (gamma,alpha)/(gamma,n) line at gamma-process temperatures is discussed, using recently published reaction rates based on global Hauser-Feshbach calculations. The results can directly be compared to previously published, classic gamma-process discussions. The nuclei exhibiting the largest sensitivity to uncertainties in nuclear structure and reaction parameters are specified.Comment: 4 pages, contribution to Nuclei in the Cosmos VIII, to appear in Nucl. Phys.

Precise half-life measurement of 110Sn and 109In isotopes

The half-lives of 110Sn and 109In isotopes have been measured with high precision. The results are T1/2 =4.173 +- 0.023 h for 110Sn and T1/2 = 4.167 +-0.018 h for 109In. The precision of the half-lives has been increased by a factor of 5 with respect to the literature values which makes results of the recently measured 106Cd(alpha,gamma)110Sn and 106Cd(alpha,p)109In cross sections more reliable.Comment: 3 pages, 2 figures, accepted for publication in Phys. Rev C as brief repor