Microbulk Micromegas for the search of 0$\nu\beta\beta$ of 136Xe in the PandaX-III experiment

TL;DR

This paper discusses the development of microbulk Micromegas detectors for high-pressure xenon TPCs, enhancing neutrinoless double beta decay searches by improving event imaging, background discrimination, and energy resolution.

Contribution

It introduces the application of microbulk Micromegas in HPXe TPCs for 0νββ searches, demonstrating their stability, low radioactivity, and improved diffusion control with TMA additive.

Findings

High gain and stability of microbulk Micromegas at high pressures

Reduced electron diffusion with TMA additive improves event topology

Potential for competitive background discrimination in 0νββ searches

Abstract

The search for the neutrinoless double beta decay (0$\nu\beta\beta$) is one of the most important quests nowadays in neutrino physics. Among the different techniques used, high pressure xenon (HPXe) gas time projection chambers (TPC) stand out because they allow to image the topology of the 0$\nu\beta\beta$ event (one straggling track ending in two blobs), and use it to discriminate signal from background events. Recent results with microbulk Micromegas in Xe + trimethylamine (TMA) mixtures show high promise in terms of gain, stability of operation, and energy resolution at high pressures (up to 10 bar). The addition of TMA at levels of ~1\% reduces electron diffusion in up to a factor of 10 with respect pure Xe, improving the quality of the topological pattern, and therefore the discrimination capability. Moreover microbulk Micromegas have very low levels of intrinsic radioactivity. All these results show that a Micromegas-read High Pressure Xenon TPC (HPXe-TPC) can be a competitive technique in the search for 0$\nu\beta\beta$. The recently proposed PandaX-III experiment, based on these results, aims at building a large TPC of 200 kg of enriched Xe, to be located at Jinping Underground laboratory in China. In this talk the main features of the experiment will be presented, with an emphasis on the design and tests of the microbulk readout, as well as the status of the project and first results of the prototyping phase.