Capture cross sections on unstable nuclei

¹ Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
² Department of Physics, University of Surrey, Guildford GU2 7XH, UK
³ Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520, USA
⁴ Department of Physics, Duke University, Durham, North Carolina 27708, USA
⁵ Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
⁶ Institut für Kernphysik, TU Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt, Germany
⁷ Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
⁸ North Carolina State University, Raleigh, North Carolina 27695, USA
⁹ Department of Physics & Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
¹⁰ ExtreMe Matter Institute and Research Division, GSI, Plankstraße1, 64291 Darmstadt, Germany
¹¹ Universität Gießen, Heinrich-Buff-Ring 16, 35392 Gießen, Germany
¹² Institut d'Astronomie et d'Astrophysique, Université Libre de Bruxelles, CP. 226, 1050 Brussels, Belgium

^a e-mail: tonchev2@llnl.gov

Published online: 13 September 2017

Abstract

Accurate neutron-capture cross sections on unstable nuclei near the line of beta stability are crucial for understanding the s-process nucleosynthesis. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining the most relevant observables that can constrain Hauser-Feshbach statistical-model calculations of capture cross sections. Specifically, we will consider photon scattering using monoenergetic and 100% linearly polarized photon beams. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes near and far from stability will be discussed.