Investigation of reactions relevant for the γ process using in-beam γ-ray spectroscopy

The reaction ⁸⁹Y(p, γ)⁹⁰Zr was studied at five proton energies close to the Gamow window. This reaction is of astrophysical importance, since it is located in a mass region, where the p-nuclei abundances are not well reproduced by network calculations. For this purpose, the in-beam technique utilizing the high-efficiency high-purity germanium (HPGe) detector array HORUS at the Tandem ion accelerator at the University of Cologne was used. The excellent agreement of the measured total cross sections with previous data shows, that the setup in Cologne is well suited for such measurements. An additional interesting outcome of this measurement are partial cross sections of the de-excitation of the ⁹⁰ Zr compund nucleus up to the 15^th excited state, an observable only accessible in this kind of high-resolution inbeam experiments. The experimental setup and preliminary results of the total and partial cross sections obtained for the ⁸⁹Y(p, γ) reaction are presented. Additionally, we show results of a first test measurement of the a-capture reaction on the p-nucleus ⁹²Mo using the in-beam technique with HPGe detectors.