A segmented total energy detector (sTED) optimized for (n, ¿) cross-section measurements at n_TOF EAR2

Abstract

The neutron time-of-flight facility n_TOF at CERN is a spallation source dedicated to measurements of neutron- induced reaction cross-sections of interest in nuclear technologies, astrophysics, and other applications. Since 2014, Experimental ARea 2 (EAR2) is operational and delivers a neutron fluence of ~ 4 · 107 neutrons per nominal proton pulse, which is ~50 times higher than the one of Experimental ARea 1 (EAR1) of ~ 8 · 105 neutrons per pulse. The high neutron flux at EAR2 results in high counting rates in the detectors that challenged the previously existing capture detection systems. For this reason, a Segmented Total Energy Detector (sTED) has been developed to overcome the limitations in the detector’s response, by reducing the active volume per module and by using a photo-multiplier (PMT) optimized for high counting rates. This paper presents the main characteristics of the sTED, including energy and time resolution, response to ¿-rays, and provides as well details of the use of the Pulse Height Weighting Technique (PHWT) with this detector. The sTED has been validated to perform neutron-capture cross-section measurements in EAR2 in the neutron energy range from thermal up to at least 400 keV. The detector has already been successfully used in several measurements at n_TOF EAR2.