Topmetal CMOS direct charge sensing plane for neutrinoless double-beta decay search in high-pressure gaseous TPC

Journal Article · Sun Oct 18 04:00:00 EDT 2020

OSTI ID:1818472

Mei, Yuan; Sun, Xiangming; Xu, Nu

We propose a novel charge sensing concept for high-pressure Time Projection Chamber (TPC) to search for Neutrinoless Double-Beta Decay (NLDBD) with ton-scale isotope mass and beyond. A meter-sized plane, tiled with an array of CMOS integrated sensors called Topmetal that directly collect charge without gas avalanche gain, is to be deployed into a high-pressure gaseous TPC with working gases containing suitable NLDBD candidate isotopes such as Xe-136 and Se-82. The Topmetal sensor has an electronic noise <30 e- per pixel, which allows the detector to reach <1% FWHM energy resolution at the NLDBD Q-value for both Xe-136 and 82SeF6 gases by measuring ionization charges alone. The elimination of charge avalanche gain allows the direct sensing of slow-drifting ions, which enables the use of highly electronegative gas SeF6 in which free electrons do not exist. It supports the swapping of working gases without hardware modification, which is a unique way to validate signals against radioactive backgrounds. Since the sensor manufacturing and plane assembling could leverage unaltered industrial mass-production processes, stability, uniformity, scalability, and cost-effectiveness that are required for ton-scale experiments could all be reached. The strengths of TPC such as 3D ionization tracking and decay daughter tagging are retained. This development could lead to a competitive NLDBD experiment at and above ton-scale. The conceptual considerations, simulations, and initial prototyping are discussed.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1818472
• Country of Publication: United States
• Language: English