nEXO Project

https://nexo.llnl.gov/
Liang Yang

Overview

The success of EXO-200 demonstrates that liquid xenon TPC technology is well suited for a large-scale double beta decay experiment. nEXO is a proposed ~ 5-tonne detector. Its design will be optimized to take full advantage of the liquid xenon TPC concept. The detector will go into to the Cryopit at SNOLab, where it will be protected from high energy cosmic rays by nearly 2-km of overburden. Preliminary sensitivity study shows that nEXO can reach 0νββ half-life sensitivity of ~ 1028 years with ten years of running time. It will be the most sensitive search for lepton number violating processes as well as the most stringent test for the Majorana nature of neutrinos.

Image (right) Artist's view of nEXO in the Cryopit at SNOlab.

nEXO R&D

A substantial R&D program is underway to validate the nEXO detector design concepts and technologies, including high voltage, photodetectors, electronics, TPC designs, radio-assay, cryogenics and interconnections. The UIUC group’s R&D efforts focus on the development of low noise and low background frontend electronics that can operate directly in liquid xenon. Such readout is necessary to achieve the required detector energy resolution, and can reduce the overall radioactivity through highly integrated circuits on clean silicon substrates and signal multiplexing for cable reduction. Our group’s research activities involve designing the overall readout architecture, testing of cryogenic ASICs for charge readout, optimizing the specifications of the frontend readouts, prototyping frontend readouts for SiPMs, and studying the performance of critical components. We have constructed a liquid xenon test station that enables us to study the performance of the frontend readout in liquid xenon. We closely collaborate with Brookhaven Lab, SLAC, Oakridge, and Indiana University on this R&D work. Prof. Yang currently serves as the co-subsystem manager for the nEXO frontend readout. The work is supported by DOE award DE-SC0014332.

Our group also has a small research project that uses radioactive ion beams at the CARIBU facility at Argonne National Lab to study the barium ion transport properties from material surfaces or inside liquid xenon. This is a step towards realizing a barium tagging system that can eliminate radioactivity induced background and can serve as a future upgrade path for nEXO.

Student Research Opportunities

We look for talented students to lead the nEXO R&D activities in our group. The students will have the opportunity to learn cutting edge detector technologies, study novel electronics designs, and contribute to the development of the next generation tonne scale double beta decay detectors.

nEXO R&D Activities