Exploring statistical properties of nuclei for explosive stellar nucleosynthesis

Auteurs

• Philipp Scholz

Paramètres

• Physique
• Sciences naturelles

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Nuclear reaction cross sections are crucial for understanding nucleosynthesis in stars, particularly for extrapolating measurements to relevant energy regions and predicting reaction rates for exotic nuclei. This thesis focuses on the gamma-strength function and the alpha+nucleus optical-model potential. Radiative proton-capture reactions on stable copper isotopes were studied using the HORUS gamma-ray spectrometer to analyze the gamma-strength in 64Zn and 66Zn. A model-independent formalism was developed to extract gamma-strength information from primary gamma-ray intensity ratios. For the first time, these intensities were measured using gamma-gamma coincidences and two-step gamma-ray cascades in (p, gamma) reactions. This technique was also applied to the previously studied 92Mo(p, gamma) reaction to obtain more precise data on the gamma-strength of the unstable N=50 isotone 93Tc. The findings enhance existing experimental data and facilitate comparisons with other methods, which is vital for evaluating the generalized Brink-Axel hypothesis in nuclear astrophysics. Additionally, cross sections of alpha-induced reactions on the p nucleus 108Cd were measured to investigate the alpha optical-model potential at sub-Coulomb energies. The combined measurement of (alpha, n) and (alpha, gamma) cross sections improved the sensitivity of the alpha optical-model potential, confirming modifications to the Demetriou potential and demons

Achat du livre

• Année de publication: 2018