Speaker
Anton Wallner
(Institut für Isotopenforschung und Kernphysik, VERA, Univ. Wien)
Description
Accurate and precise cross-section data are the key ingredients to our understanding
of stellar nucleosynthesis. Common techniques for these data comprise online
time-of-flight measurements of reaction cross sections as well as offline methods
like the activation technique. In cases of longer-lived nuclides or nuclides with an
unfavourable decay scheme, counting atoms directly rather than their decay rates, is
the far more sensitive method. Accelerator mass spectrometry (AMS) offers a powerful
tool to measure cross sections independent on half-lives of reaction products.
At the Vienna Environmental Research Accelerator (VERA) we are pursuing a program to
study cross sections relevant to nuclear astrophysics. In this context, various
samples are irradiated in a quasi-stellar neutron spectrum of kT = 25 keV produced
with the 7Li(p,n)7Be reaction at the 3.7MV Van de Graaff accelerator of
Forschungszentrum Karlsruhe. The subsequent AMS measurements are performed at VERA.
The main challenge in AMS is to discriminate isotopic and isobaric interferences. By
extensive background studies the required sensitivity for cross section measurements
has been demonstrated for various isotopes prior to the AMS measurements.
So far, the reactions 9Be(n,g)10Be, 13C(n,g)14C, 40Ca(n,g)41Ca, 54Fe(n,g)55Fe, and
209Bi(n,g)210Bi have been investigated. For some of these reactions no experimental
results exist up to now. The implications of measured cross sections for various
nucleosynthesis scenarios will be discussed.
Author
Anton Wallner
(Institut für Isotopenforschung und Kernphysik, VERA, Univ. Wien)
Co-authors
Dr
Alfred Priller
(Institut für Isotopenforschung und Kernphysik, VERA, Univ. Wien)
Dr
Christof Vockenhuber
(TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3, Canada)
Dr
Franz Käppeler
(Institut für Kernphysik, Forschungszentrum Karlsruhe, Postfach 3640, 76021 Karlsruhe, Germany)
Dr
Iris Dillmann
(Institut für Kernphysik, Forschungszentrum Karlsruhe, Postfach 3640, 76021 Karlsruhe, Germany)
Prof.
Michael Paul
(Racah Institute of Physics, Hebrew University, Jerusalem, Israel, 91904)
Dr
Peter Steier
(Institut für Isotopenforschung und Kernphysik, VERA, Univ. Wien)
Dr
Robin Golser
(Institut für Isotopenforschung und Kernphysik, VERA, Univ. Wien)
Prof.
Walter Kutschera
(Institut für Isotopenforschung und Kernphysik, VERA, Univ. Wien)
