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

Abstract

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 (∼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,γ) 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,γ) 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 79 Se(n,γ).

The n_TOF facility at CERN

“…Thanks to the upgrade of the facility and the development of innovative detection setups during LS2, the experimental investigation of previously unexplored physics cases became feasible (e.g. measurement of the 79 Se(𝑛𝑛,𝛾𝛾), reaction cross section) [12]. A significant part of the available beam time is devoted to further detector developments and tests that revealed the abilities of the n_TOF facility to launch new type of measurements in the near future.…”

Status report of the n_TOF facility after the 2nd CERN long shutdown period

“…Thanks to the development of innovative detection setups during LS2, the experimental investigation of previously unexplored physics cases became feasible (e.g. measurement of the 79 Se(n, γ ) reaction cross section) [19]. A significant part of the available beam time was devoted to further detector developments and tests that revealed the abilities of the n_TOF facility to launch new type of measurements in the near future.…”

“…18 Sezione di Trieste, Istituto Nazionale di Fisica Nucleare, Trieste, Italy. 19 Department of Physics, University of Trieste, Trieste, Italy. 20 National Technical University of Athens, Athens, Greece.…”