A measurement of the C-14(n, gamma)C-15 cross section at a stellar temperature of kT = 23.3 keV

Abstract

A fast cyclic activation technique is used to determine the capture cross section of C-14. The measurements were carried out at the Karlsruhe 3.75-MV pulsed Van de Graaff accelerators using the 7Li(p, n) reaction close to the reaction threshold to generate neutrons with a distribution resembling a Maxwell spectrum of 25 keV. The activation sample consisted of 605 +/- 15 mg carbon powder enriched in C-14 by 89 percent. The C-14 capture cross section was measured relative to the Au-197 standard cross section. The activity produced by the neutron captures in the C-14 sample was counted with a high-resolution HPGe detector via the characteristic 5297.79 keV C-15 gamma-ray line. The C-14 capture cross section at 23.3 keV was found to be (1.72 +/- 0.43) microbarn.