Characterization of the NEXT-White Detector with Calibration Data

The NEXT (Neutrino Experiment with a Xenon TPC) experiment will search for neutrinoless double-beta (0νββ 0\nu\beta\beta ) decay in 136 ^{136} Xe with a high pressure xenon gas time projection chamber (TPC). Two principle advantages of the NEXT approach are good energy resolution and topology-based event classification. We describe initial results from the first phase of the experiment, the detector NEXT-White deployed in the Canfranc Underground Laboratory in the Spanish Pyrenees, demonstrating recent progress towards sub-1% energy resolution at the 136 ^{136} Xe double-beta Q-value. We also present the results of a topological analysis, using electron-positron pair events in place of the two-electron events expected from 0νββ 0\nu\beta\beta , which demonstrates how such events can be distinguished from background (single-electron) events of the same energy through the use of deep neural networks (DNNs).