NEXT-100 is an electroluminescent high-pressure xenon gas time projection chamber that will search for the neutrinoless double beta (0νββ) decay of ¹³⁶Xe. The detector possesses two features of great value for 0νββ searches: energy resolution better than 1% FWHM at the Q value of ¹³⁶Xe and track reconstruction for the discrimination of signal and background events. This combination results in excellent sensitivity, as discussed in this paper. Material-screening measurements and a detailed Monte Carlo detector simulation predict a background rate for NEXT-100 of at most 4 × 10⁻⁴ counts keV⁻¹ kg⁻¹ yr⁻¹. Accordingly, the detector will reach a sensitivity to the 0νββ-decay half-life of 2.8 × 10²⁵ years (90% CL) for an exposure of 100 kg·year, or 6.0 × 10²⁵ years after a run of 3 effective years. Open image in new window

The NEXT experiment aims to observe the neutrinoless double beta decay of ¹³⁶Xe in a high-pressure xenon gas TPC using electroluminescence (EL) to amplify the signal from ionization. One of the main advantages of this technology is the possibility to reconstruct the topology of events with energies close to Q _ββ . This paper presents the first demonstration that the topology provides extra handles to reject background events using data obtained with the NEXT-DEMO prototype.

Single neutral pion production via muon antineutrino charged-current interactions in plastic scintillator (CH) is studied using the MINERvA detector exposed to the NuMI low-energy, wideband antineutrino beam at Fermilab. Measurement of this process constrains models of neutral pion production in nuclei, which is important because the neutral-current analog is a background for ν¯e appearance oscillation experiments. The differential cross sections for π0 momentum and production angle, for events with a single observed π0 and no charged pions, are presented and compared to model predictions. These results comprise the first measurement of the π0 kinematics for this process