R2D2 TPC: first Xenon results

TL;DR

This paper reports on the first results of using a spherical and cylindrical TPC with xenon gas for neutrinoless double beta decay detection, demonstrating promising energy resolution with the cylindrical design at 1 bar.

Contribution

It compares spherical and cylindrical TPC geometries with xenon gas, providing new performance data and demonstrating the feasibility of using TPCs for $etaeta0 u$ searches.

Findings

Cylindrical TPC achieved 1.4% energy resolution at 1 bar with xenon.

Spherical TPC showed lower energy resolution under similar conditions.

Extended gas pressure range up to 3 bar was tested.

Abstract

Radial time projection chambers (TPC), already employed in the search for rare phenomena such as light Dark Matter candidate, could provide a new detection approach for the search of neutrinoless double beta decay ($\beta\beta0\nu$). The assessment of the performances of such a detector for $\beta\beta0\nu$ search is indeed the goal of the Rare Decays with Radial Detector (R2D2) R\&D. Promising results operating a spherical TPC with argon up to 1~bar have been published in 2021. Supplementary measurements were recently taken extending the gas pressure range up to 3~bar. In addition, a comparison between two detector geometries, namely spherical (SPC for spherical proportional counter) and cylindrical (CPC for cylindrical proportional counter), was performed. Using a relatively simple gas purification system the CPC detector was also operated with xenon at 1~bar: an energy resolution of 1.4\% full-width at half-maximum was achieved for drift distances up to 17~cm. Much lower resolution was observed with the SPC. These results are presented in this article.