Signal Processing and Electronic Noise in LZ

TL;DR

This paper characterizes the noise performance and linearity of the LZ dark matter detector's electronics, including amplifiers and digitizers, through extensive testing with simulated signals.

Contribution

It provides detailed measurements of noise levels and saturation effects in the LZ detector electronics, aiding future optimization and performance assessment.

Findings

Measured RMS ADC noise of 1.19 ADCC

Noise remained stable with high-energy signals

Estimated low-energy channel noise at 0.38 ADCC

Abstract

The electronics of the LUX-ZEPLIN (LZ) experiment, the 10-tonne dark matter detector to be installed at the Sanford Underground Research Facility (SURF), consists of low-noise dual-gain amplifiers and a 100-MHz, 14-bit data acquisition system for the TPC PMTs. Pre-prototypes of the analog amplifiers and the 32-channel digitizers were tested extensively with simulated pulses that are similar to the prompt scintillation light and the electroluminescence signals expected in LZ. These studies are used to characterize the noise and to measure the linearity of the system. By increasing the amplitude of the test signals, the effect of saturating the amplifier and the digitizers was studied. The RMS ADC noise of the digitizer channels was measured to be 1.19 $\pm$ 0.01 ADCC. When a high-energy channel of the amplifier is connected to the digitizer, the measured noise remained virtually unchanged, while the noise added by a low-energy channel was estimated to be 0.38 $\pm$ 0.02 ADCC (46 $\pm$ 2$\mu$V). A test facility is under construction to study saturation, mitigate noise and measure the performance of the LZ electronics and data acquisition chain.