Initial results of NEXT-DEMO, a large-scale prototype of the NEXT-100 experiment

TL;DR

NEXT-DEMO, a large-scale prototype of the NEXT-100 detector, demonstrates promising energy resolution and event topology reconstruction capabilities, validating its design for neutrinoless double beta decay searches in high-pressure xenon gas.

Contribution

This work presents the first results of NEXT-DEMO, confirming its performance aligns with the goals for the NEXT-100 experiment in detecting rare nuclear decays.

Findings

Achieved 1.75% FWHM energy resolution at 511 keV

Extrapolates to 0.8% FWHM at 2.5 MeV

Proved event topology identification in high-pressure xenon

Abstract

NEXT-DEMO is a large-scale prototype of the NEXT-100 detector, an electroluminescent time projection chamber that will search for the neutrinoless double beta decay of Xe-136 using 100 to 150 kg of enriched xenon gas. NEXT-DEMO was built to prove the expected performance of NEXT-100, namely, energy resolution better than 1% FWHM at 2.5 MeV and event topological reconstruction. In this paper we describe the prototype and its initial results. A resolution of 1.75% FWHM at 511 keV (which extrapolates to 0.8% FWHM at 2.5 MeV) was obtained at 10 bar pressure using a gamma-ray calibration source. Also, a basic study of the event topology along the longitudinal coordinate is presented, proving that it is possible to identify the distinct dE/dx of electron tracks in high-pressure xenon using an electroluminescence TPC.