Neutron Activation of 74Ge and 76Ge
Kepler Center for Astro and Particle Physics, Eberhard Karls Universität
2 Institut für Radiochemie, Technische Universität München, D-85748 Garching, Germany
3 Institut für Kernphysik, Universität zu Köln, D-50937 Cologne, Germany
4 Forschungs-Neutronenquelle Heinz Maier-Leibnitz FRM II, Technische Universität München D-85748 Garching, Germany
The upcoming GERDA and MAJORANA experiments will use germanium crystals, isotopically enriched in 76Ge to search for the neutrinoless double beta decay (0ν2β). The very long half-life of 0ν2β (> 1025 y for 76Ge) requires an extremely low background level. Neutrons induced by cosmic muons can be captured after thermalization by 74Ge or 76Ge, followed by β− -decay of 75Ge and 77Ge respectively. The prompt γ-cascade after neutron capture and the β-decay contribute to the total backround in these experiments. For a good estimation of the background the poorly known cross-sections for the 74Ge(n,γ)75,75mGe reactions were measured using targets, isotopically depleted in 76Ge. Furthermore the prompt γ-rays in 77Ge were measured with isotopically enriched germanium targets. The results of the latter measurement were combined with the results of a dedicated coincidence measurement to reconstruct the prompt γ-ray decay scheme.
© Owned by the authors, published by EDP Sciences, 2010