Prototype of the Readout Electronics for WCDA in LHAASO

TL;DR

This paper presents the design and testing of a prototype readout electronics system for WCDA in LHAASO, achieving high precision timing and charge measurements over a large dynamic range with simplified architecture.

Contribution

It introduces a novel readout electronics prototype with integrated clock distribution and high-speed data transfer for WCDA in LHAASO.

Findings

Charge resolution better than 10% RMS at 1 P.E.

Time resolution better than 300 ps RMS.

Successful validation over the entire dynamic range.

Abstract

In the Large High Altitude Air Shower Observatory (LHAASO), the Water Cherenkov Detector Array (WCDA) is one of the key parts. The WCDA consists of 3600 Photomultiplier Tubes (PMTs) scattered in a 90000 m2 area, and both high precision time and charge measurements are required over a large dynamic range from 1 to 4000 Photo Electrons (P.E.). To achieve time measurement precision better than 500 ps RMS, high quality clock distribution and automatic phase compensation are needed among the 400 Front End Electronics (FEE) modules. To simplify the readout electronics architecture, clock, data, and commands are transferred simultaneously over 400-meter fibers, while high speed data transfer interface is implemented based on TCP/IP protocol. Design and testing of the readout electronics prototype for WCDA is presented in this paper. Test results indicate that a charge resolution better than 10% RMS @ 1 P.E. and 1% RMS @ 4000 P.E., and a time resolution better than 300 ps RMS are successfully achieved over the whole dynamic range, beyond the application requirement.