Application of a novel method to characterize the performance of zero suppression in the LUX-ZEPLIN experiment*

The LUX-ZEPLIN (LZ) experiment, located at Sanford Underground Research Facility, is a direct detection dark matter experiment optimized to search for WIMPs. The LZ data acquisition (DAQ) system digitizes signals from 745 PMTs in three detector volumes. Zero suppression (ZS) is implemented to remove periods containing only baseline noise. To verify ZS we used a novel DAQ operation mode, for which both the raw and ZS waveforms are captured simultaneously.

 

Three independent studies were carried out to evaluate the performance of ZS: 1) The bit consistency is checked by comparing each sample of the ZS data with the raw waveforms. 2) The zero suppression algorithm implemented on the FPGA is simulated in Python, applied to the raw waveforms, and compared with the ZS data. 3) Python-based tools are utilized to look for peaks in the raw waveforms, and the results of this analysis are used to validate the ZS algorithm.

This DAQ mode provides the powerful ability to carry out cross-checks on real data with the hardware in-situ. These studies were extremely valuable while commissioning the LZ DAQ and are used biannually to monitor the performance of the signal and DAQ chain. We will present details of these studies and their results.