Latest results of NEXT-DEMO, the prototype of the NEXT 100 double beta decay experiment

TL;DR

The paper reports on the latest performance results of the NEXT-DEMO prototype, a scaled model of the NEXT100 detector, demonstrating high energy resolution and detailed characterization of xenon gas properties for neutrinoless double beta decay searches.

Contribution

It presents new calibration and measurement techniques for the NEXT-DEMO detector, improving understanding of detector response and background sources for future neutrinoless double beta decay experiments.

Findings

Achieved 5.5% FWHM energy resolution at 30 keV, extrapolating to 0.6% at Q value.

Measured xenon gas properties such as electron drift velocity and diffusion.

Quantified radon activity as a background source.

Abstract

NEXT-DEMO is a 1:4.5 scale prototype of the NEXT100 detector, a high-pressure xenon gas TPC that will search for the neutrinoless double beta decay of $^{136}$Xe. X-ray energy depositions produced by the de-excitation of Xenon atoms after the interaction of gamma rays from radioactive sources have been used to characterize the response of the detector obtaining the spatial calibration needed for close-to-optimal energy resolution. Our result, 5.5% FWHM at 30 keV, extrapolates to 0.6% FWHM at the Q value of $^{136}$Xe. Additionally, alpha decays from radon have been used to measure several detection properties and parameters of xenon gas such as electron-ion recombination, electron drift velocity, diffusion and primary scintillation light yield. Alpha spectroscopy is also used to quantify the activity of radon inside the detector, a potential source of background for most double beta decay experiments.