Development of a ¹²⁷Xe calibration source for nEXO

The nEXO experiment is a planned tonne-scale liquid xenon time projection chamber (TPC) to search for neutrinoless double beta decay of ¹³⁶Xe with a half-life sensitivity beyond 10²⁸ years. For optimal energy resolution in nEXO, the position- and time- dependent detector response must be calibrated to sufficient precision. Dissolved sources which mix uniformly throughout the TPC are being considered as an alternative to external gamma sources for this purpose. In this talk I will describe the development of a dissolved ¹²⁷Xe source for nEXO, including a demonstration of its use for electron lifetime calibrations in a test TPC. I will also show projections of the precision with which such a source could be used to calibrate the charge and light response in nEXO.