Energy calibration of the NEXT-White detector with 1% resolution near Qββ of 136Xe

Abstract

Excellent energy resolution is one of the primary advantages of electroluminescent high-pressure xenon TPCs. These detectors are promising tools in searching for rare physics events, such as neutrinoless double-beta decay (ββ0ν), which require precise energy measurements. Using the NEXT-White detector, developed by the NEXT (Neutrino Experiment with a Xenon TPC) collaboration, we show for the first time that an energy resolution of 1% FWHM can be achieved at 2.6 MeV, establishing the present technology as the one with the best energy resolution of all xenon detectors for ββ0ν searches.

Results and future plans of the NEXT double beta decay experiment

“…The main gamma peaks from the decay chains of these sources can be seen clearly. As reported in [4], a FWHM energy resolution of ∼0.91% is obtained at the energy of Q β β . The same source data can be used to study the power Counts/bin 137…”

“…The technology was first demonstrated with kg-scale detectors [1,2] and is currently being exploited at a larger scale by the Next-White detector at Laboratorio Subterráneo de Canfranc (LSC) [3,4,5]. A rich scientific program is currently developing the next stage detector (Next-100) while looking to the future with multiple R&D efforts for a tonne-scale NEXT.…”

“…Reconstructed energy spectrum from events selected from interactions induced by 137 Cs and 228 Th sources[4].…”

Cosmogenic Activation in Double Beta Decay Experiments

“…Several prototypes (with mass of ∼1 kg) were designed and operated in a first step to demonstrate the advantages of the technology, including a distinctive signal topology and very good energy resolution [158,159]. As a second phase, the NEXT-White demonstrator (with 5 kg of xenon) was built in Canfranc [160] and in 2020 is running smoothly, having confirmed the background discrimination capability from the topological signature [161] and shown an energy resolution of 1% (FWHM) in the region of interest [162]; energy resolution, which depends on the stability of operation parameters, wave-shifters, light detectors, and other elements, is much better in xenon gas than in liquid because the fluctuations in the ionization production are smaller than the ones due to pure Poisson statistics (Fano factor is lower than 1 in gaseous phase). NEXT-100 (with 100 kg of xenon at 15 bar) is the next stage of the program [163], built with radiopure specifications [164] as a scale up of NEXT-White by 2:1 in size; operation might start in 2021.…”

Low-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield

“…The amplification of ionisation electron signals through xenon electroluminescence (EL) allows achieving both higher detector signal-to-noise ratio [9,10], due to the additional gain of the photosensor, and lower statistical fluctuations when compared to charge avalanche multiplication [11]. At 10 bar, the best energy resolution achieved with a 1kgscale prototype based on Micromegas was extrapolated to around 3%-FWHM at the xenon Q ββ (2.45 MeV) [12], while a 1 kg-and a 10 kg-scale EL-based TPC achieved energy resolution values consistently below 1%-FWHM [13,14]. The EL readout through photosensors electrically and mechanically decouples the amplification region from the readout, rendering the system more immune to electronic noise, radiofrequency pickup and high voltage issues.…”