Research of time discrimination circuits for PMT signal readout over large dynamic range in LHAASO WCDA

TL;DR

This paper presents a novel time discrimination circuit for LHAASO WCDA PMT readout, achieving high resolution and reduced dead time over a large dynamic range, enhancing detector performance.

Contribution

The work introduces an improved time discrimination circuit design that reduces dead time and maintains high resolution across a wide dynamic range for PMT signals.

Findings

Achieved better than 500 ps RMS time resolution across the dynamic range.

Reduced circuit dead time to less than 200 ns.

Validated performance through laboratory testing and simulations.

Abstract

In the readout electronics of the Water Cerenkov Detector Array (WCDA) in the Large High Altitude Air Shower Observatory (LHAASO), both high-resolution charge and time measurement are required over a dynamic range from 1 photoelectron (P.E.) to 4000 P.E. for the PMT signal readout. In this paper, we present our work on the design of time discrimination circuits in LHAASO WCDA, especially on improvement to reduce the circuit dead time. Several approaches were studied through analysis and simulations, and actual circuits were designed and tested in the laboratory to evaluate the performance. Test results indicate that a time resolution better than 500 ps RMS is achieved in the whole large dynamic range, and the circuit dead time is successfully reduced to less than 200 ns.