# Near-Intrinsic Energy Resolution for 30 to 662 keV Gamma Rays in a High Pressure Xenon Electroluminescent TPC

## TL;DR

This paper demonstrates near-intrinsic energy resolution in a high-pressure xenon TPC for gamma rays up to 662 keV, advancing the potential for neutrino-less double beta decay detection with improved resolution over existing liquid xenon experiments.

## Contribution

The study presents the first results of a high-pressure xenon electroluminescent TPC achieving unprecedented energy resolution, crucial for next-generation double beta decay experiments.

## Key findings

- Achieved ~1% FWHM energy resolution at 662 keV
- Demonstrated ~5% FWHM resolution at 30 keV
- Projected 0.5% resolution at 2,459 keV for 0νββ

## Abstract

We present the design, data and results from the NEXT prototype for Double Beta and Dark Matter (NEXT-DBDM) detector, a high-pressure gaseous natural xenon electroluminescent time projection chamber (TPC) that was built at the Lawrence Berkeley National Laboratory. It is a prototype of the planned NEXT-100 $^{136}$Xe neutrino-less double beta decay ($0\nu\beta\beta$) experiment with the main objectives of demonstrating near-intrinsic energy resolution at energies up to 662 keV and of optimizing the NEXT-100 detector design and operating parameters. Energy resolutions of $\sim$1% FWHM for 662 keV gamma rays were obtained at 10 and 15 atm and $\sim$5% FWHM for 30 keV fluorescence xenon X-rays. These results demonstrate that 0.5% FWHM resolutions for the 2,459 keV hypothetical neutrino-less double beta decay peak are realizable. This energy resolution is a factor 7 to 20 better than that of the current leading $0\nu\beta\beta$ experiments using liquid xenon and thus represents a significant advancement. We present also first results from a track imaging system consisting of 64 silicon photo-multipliers recently installed in NEXT-DBDM that, along with the excellent energy resolution, demonstrates the key functionalities required for the NEXT-100 $0\nu\beta\beta$ search.