12C(p,γ13N and 13C(p,γ)14N
PI: Axel Boeltzig
Astrophysical Motivation:
Precise knowledge of the reactions 12C(p,γ)13N and 13C(p,γ)14N is relevant for the understanding of stellar evolution, as they affect the abundance profiles of C isotopes in the hydrogen-burning zone of stars.
Experimental Aims
Past experiments used different techniques to measure the distinct signatures of both reactions - a low Q-value reaction with an unstable daughter nucleus in the case of 12C, and a large Q-value with a stable daughter nucleus in the case of 13C. In view of the existing data sets, a reliable normalization of the measured cross section is crucial. A combination of different target thicknesses, carbon isotopic compositions and detection techniques are part of this measurement at the LUNA-400 accelerator, to reduce the number of common systematic uncertainties.
Experimental Setup
The measurements are performed with two detection approaches in overlapping beam energy ranges. At higher energies, a High-Purity Germanium (HPGe) detector is used for prompt gamma-ray spectroscopy and target profile studies. For lower energies, a segmented Bismuth Germanium Oxide (BGO) scintillation detector is used to for a highly efficient detection of the total gamma energy in 13C(p,γ), as well as for an activation measurement of 13N produced through 12C(p,γ)
Target and detectors are shielded by lead to reduce backgrounds from environmental gamma-rays.