Topological background discrimination in the PandaX-III neutrinoless double beta decay experiment

Abstract

The PandaX-III experiment plans to search for neutrinoless double beta decay (0νββ) of 136Xe in the China JinPing underground Laboratory (CJPL). The experiment will use a high pressure gaseous time projection chamber (TPC) to register both the energy and the electron track topology of an event. This article is devoted to demonstrate our particular detector setup capabilities for the identification of 0νββ and the consequent background reduction. As software tool we use REST, a framework developed for the reconstruction and simulation of TPC-based detector systems. We study the potential for background reduction by introducing appropriate parameters based on the properties of 0νββ events. We exploit for the first time not only the energy density of the electron track-ends, but also the electron scattering angles produced by an electron near the end of its trajectory. To implement this, we have added new algorithms for detector signal and track processing inside REST. Their assessment shows that background can be reduced by about 7 orders of magnitude while keeping 0νββ efficiency above 20% for the PandaX-III baseline readout scheme, a two-dimensional 3 mm pitch stripped readout. More generally, we use the potential of REST to handle 2D/3D data to assess the impact on signal-to-background significance at different detector granularities, and to validate the PandaX-III baseline choice. Finally, we demonstrate the additional potential to discriminate surface background events generated at the readout plane in the absence of t o , by making use of event parameters related with the diffusion of electrons.

Signal identification with Kalman Filter towards background-free neutrinoless double beta decay searches in gaseous detectors

“…The background rate is 3.1 times smaller than the one with the original feature cuts developed in ref. [12] and meanwhile the signal efficiency is 1.5 times higher. Assuming null results, the exclusion limits are established following a method outlined in ref.…”

“…The detector response of TPC, including electron diffusion, readout schemes, and energy resolution, is simulated in the REST framework [12]. While drifting to the readout plane, ionization electrons diffuse transversely and longitudinally which results in broadening of the tracks.…”

“…More recently, the NEXT experiment [8] demonstrated the effective track reconstruction with electroluminescence amplification signals in their prototype TPC [9]. Efficiencies of signal and background identification in the proposed PandaX-III gaseous TPC [10] have been studied with simulation data [11,12]. The aforementioned experiments utilize the JHEP06(2021)106 prominent Bragg Blob (BB) feature of event tracks.…”

Theia: an advanced optical neutrino detector

“…The parameters of the other experiments are taken from Refs. [147][148][149][150][151] archy is about 10 times the world annual production, which makes the use of Xe likely impractical.…”

Cosmogenic Activation in Double Beta Decay Experiments

“…The PandaX-III ("Particle In addition, Astrophysical Xenon Experiment III") experiment is working to build firstly a TPC with Microbulk Micromegas readout for tracking and 200 kg of enriched xenon (90% in 136 Xe) operated at 10 bar in the Jinping laboratory [167]. The background discrimination from track analysis has been studied [168]. As a second step, the implementation of five of such TPCs is foreseen.…”