Cryogenic Electronics Readout for the nEXO Experiment*

The next Enriched Xenon Observatory (nEXO) is a proposed 5-ton monolithic liquid xenon TPC searching for evidence of the neutrinoless double beta decay of ¹³⁶Xe.  The sensitivity approaches T_1/2 = 10²⁸ years, and the current energy resolution benchmark is <1%.

The required energy resolution calls for the use of cryogenic electronics to perform functions from signal collection to digitization for both charge and scintillation measurement.  In situ cold electronics minimizes capacitance, electromagnetic interference, transistor noise, and feedthrough/cabling material.  Similar cold electronic readouts have been successfully implemented in the MicroBooNE and protoDUNE experiments, validating the design concept.  However, neither of these experiments necessitated radiopurity limitations.

The addition of the radiopurity requirement informs the design in every aspect, from IC packaging and design to the substrate material to the interconnections and design of the collection tile.  This talk will present an overview of the evolution of cold electronics and the current design considerations and progress of cryogenic electronics readout for nEXO.