  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 $4\times 10^7$ neutrons per nominal proton pulse, which is 50 times higher
than the one of Experimental ARea 1 (EAR1) of $8\times10^5$ 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 detectors response, by reducing the active volume per
module and by using a photomultiplier (PMT) optimized for high counting rates.
This paper presents the main characteristics of the sTED, including energy and
time resolution, response to $\gamma$-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.
