New detection systems for an enhanced sensitivity in key stellar (n,γ) measurements

Neutron capture cross-section measurements are fundamental in the study of astrophysical phenomena, such as the slow neutron capture (s-) process of nucleosynthesis operating in red-giant and massive stars. However, neutron capture measurements via the time-of-flight (TOF) technique on key s-process nuclei are often challenging. Difficulties arise from the limited mass (similar to mg) available and the high sample-related background in the case of the unstable s-process branching points. Measurements on neutron magic nuclei, that act as s-process bottlenecks, are affected by low (n,gamma) cross sections and a dominant neutron scattering background. Overcoming these experimental challenges requires the combination of facilities with high instantaneous flux, such as n_TOF-EAR2, with detection systems with an enhanced detection sensitivity and high counting rate capabilities. This contribution reviews some of the latest detector developments in detection systems for (n,gamma) measurements at n_TOF, such as i-TED, an innovative detection system which exploits the Compton imaging technique to reduce the dominant neutron scattering background and s-TED, a highly segmented total energy detector intended for high flux facilities. The discussion will be illustrated with results of the first measurement of key the s-process branching-point reaction Se-79(n,gamma).

Automated summary

Neutron capture cross-section measurements are crucial for studying astrophysical phenomena like the s-process of nucleosynthesis in stars. However, measuring neutron capture using the time-of-flight technique is often challenging due to limited sample mass and high sample background. Overcoming these challenges requires facilities with high flux and sensitive detection systems. This contribution reviews recent developments in detection systems for neutron capture measurements, such as i-TED and s-TED, and presents the results of the first measurement of Se-79(n,gamma), a key s-process reaction.