Betatron function measurements using the gated turn-by-turn monitors at SuperKEKB

The SuperKEKB collider (2016-) is a major upgrade to the KEKB collider (1998-2010) at KEK. In the SuperKEKB commissioning Phases 2 (Feb.-Jul. 2018) and 3 (from Mar. 2019), the betatron phase advances between adjacent beam position monitors and betatron functions have been measured using a total of 138 gated turn-by-turn monitors. A fast RF gating of the monitors enables turn-by-turn beam position detections by focusing only on an artificially-excited non-colliding bunch, while leaving colliding bunches unaffected. In this proceedings, we will present the optics measurement results for SuperKEKB Phases 2 and 3, and discuss advanced signal-extraction methods such as NAFF and independent component analysis. (author)