Event Reconstruction in LZ for Dark Matter Direct Detection

The LUX-ZEPLIN (LZ) Dark Matter experiment is a multi-tonne dual-phase liquid and gaseous xenon time projection chamber that aims to achieve world-leading sensitivity to dark matter. Energy depositions in the detector yield photons and electrons in the form of prompt scintillation light (S1) and delayed electroluminescent light (S2). In order to conduct a dark matter search, LZ must be able to accurately reconstruct events based on S1 and S2 light in the detector. Pulse finding is done using difference of Gaussians (DoG) filters, while the classification of found pulses is dependent on a logical decision tree of pulse parameters such as rise time, area, and PMT coincidence. Lastly, event classification into single scatter, multiple scatter, pile-up, and other scatters is done via a sorting algorithm that takes into account the relative timings of the different pulses in an event window. To ensure that potential dark matter single scatter events are accurately identified against the much larger background of other event morphologies, it is crucial that the event classification is as accurate and efficient as possible. In this talk I will present on the development and validation of the event reconstruction algorithms for LZ.