title: Novel method to study neutron capture of 235U and 238U simultaneously at keV energies.
abstract: The neutron capture cross sections of the main uranium isotopes, (235)U and (238)U, were measured simultaneously for keV energies, for the first time by combining activation technique and atom counting of the reaction products using accelerator mass spectrometry. New data, with a precision of 3%-5%, were obtained from mg-sized natural uranium samples for neutron energies with an equivalent Maxwell-Boltzmann distribution of kT ∼ 25 keV and for a broad energy distribution peaking at 426 keV. The cross-section ratio of (235)U(n,γ)/(238)U(n,γ) can be deduced in accelerator mass spectrometry directly from the atom ratio of the reaction products (236)U/(239)U, independent of any fluence normalization. Our results confirm the values at the lower band of existing data. They serve as important anchor points to resolve present discrepancies in nuclear data libraries as well as for the normalization of cross-section data used in the nuclear astrophysics community for s-process studies.
authors.affiliation: Department of Nuclear Physics, RSPE, Australian National University, Canberra, Australian Capital Territory 0200, Australia and Faculty of Physics, VERA, Isotope Research & Nuclear Physics, University of Vienna, 1090 Vienna, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Wallner
authors.affiliation: Nuclear Analysis and Radiography Department (NARD), Centre for Energy Research, Hungarian Academy of Sciences, 1525 Budapest, Hungary.
authors.forename: T
authors.initials: T
authors.lastname: Belgya
authors.affiliation: Atominstitut, Vienna University of Technology, 1040 Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Bichler
authors.affiliation: Faculty of Physics, VERA, Isotope Research & Nuclear Physics, University of Vienna, 1090 Vienna, Austria and Atominstitut, Vienna University of Technology, 1040 Vienna, Austria.
authors.forename: K
authors.initials: K
authors.lastname: Buczak
authors.affiliation: Institut für Kernphysik, Karlsruhe Institute of Technology (KIT), Campus North, 76021 Karlsruhe, Germany and TRIUMF, Vancouver, British Columbia V6T2A3, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Dillmann
authors.affiliation: Institut für Kernphysik, Karlsruhe Institute of Technology (KIT), Campus North, 76021 Karlsruhe, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Käppeler
authors.affiliation: Faculty of Physics, VERA, Isotope Research & Nuclear Physics, University of Vienna, 1090 Vienna, Austria and Institute for Applied Physics, Goethe University Frankfurt, 60438 Frankfurt, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Lederer
authors.affiliation: Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile (ENEA), 40129 Bologna, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Mengoni
authors.affiliation: Faculty of Physics, VERA, Isotope Research & Nuclear Physics, University of Vienna, 1090 Vienna, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Quinto
authors.affiliation: Faculty of Physics, VERA, Isotope Research & Nuclear Physics, University of Vienna, 1090 Vienna, Austria.
authors.forename: P
authors.initials: P
authors.lastname: Steier
authors.affiliation: Nuclear Analysis and Radiography Department (NARD), Centre for Energy Research, Hungarian Academy of Sciences, 1525 Budapest, Hungary.
authors.forename: L
authors.initials: L
authors.lastname: Szentmiklosi