Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

A waveform and time digitization mainboard prototype for the hybrid digital optical module of TRIDENT neutrino experiment

Guangping Zhang, Yong Yang, Donglian Xu

TL;DR

The TRIDENT project aims to build a deep-sea neutrino telescope to detect astrophysical neutrinos via Cherenkov light. The authors present a custom waveform and time digitization mainboard for the hDOM, combining a 32-channel 125 MS/s ADC (AD9083), an FPGA-based 56-channel TDC, and White-Rabbit timing to achieve sub-nanosecond timing with robust SPE discrimination. Key contributions include simultaneous PMT waveform digitization, clear SPE pedestal separation with linearity up to 240 PE, and sub-ns timing resolution for PMT/SiPM pulse leading edges, validated through charge and timing tests and calibrated with in-lab and in-situ methods. The work enables the first hDOM sea trial (Fall 2025) by providing reliable, high-channel-count waveform and timing readout essential for accurate photon timing and event reconstruction in a deep-sea neutrino observatory.

Abstract

The TRIDENT (Tropical Deep-sea Neutrino Telescope) experiment is a next-generation underwater neutrino observatory planned for deployment in the West Pacific Ocean, designed to detect astrophysical neutrinos through Cherenkov radiation. The full-scale detector will consist of approximately 1000 vertical strings, each equipped with 20 hybrid digital optical modules (hDOMs) containing both photomultiplier tubes (PMTs) and silicon photomultipliers (SiPMs) for comprehensive light detection. This paper presents a custom-designed digitization mainboard prototype for the hDOM, featuring simultaneous 32-channel PMT waveform digitization at 125 MS/s using commercial analog-to-digital converters and 56-channel high-precision time measurement through field-programmable gate array -implemented time-to-digital converters. The system demonstrates excellent performance in single photoelectron (PE) detection with clear pedestal separation, maintains linear response up to 240 PEs, and achieves sub-nanosecond timing resolution for PMT or SiPM pulse edges.

A waveform and time digitization mainboard prototype for the hybrid digital optical module of TRIDENT neutrino experiment

TL;DR

The TRIDENT project aims to build a deep-sea neutrino telescope to detect astrophysical neutrinos via Cherenkov light. The authors present a custom waveform and time digitization mainboard for the hDOM, combining a 32-channel 125 MS/s ADC (AD9083), an FPGA-based 56-channel TDC, and White-Rabbit timing to achieve sub-nanosecond timing with robust SPE discrimination. Key contributions include simultaneous PMT waveform digitization, clear SPE pedestal separation with linearity up to 240 PE, and sub-ns timing resolution for PMT/SiPM pulse leading edges, validated through charge and timing tests and calibrated with in-lab and in-situ methods. The work enables the first hDOM sea trial (Fall 2025) by providing reliable, high-channel-count waveform and timing readout essential for accurate photon timing and event reconstruction in a deep-sea neutrino observatory.

Abstract

The TRIDENT (Tropical Deep-sea Neutrino Telescope) experiment is a next-generation underwater neutrino observatory planned for deployment in the West Pacific Ocean, designed to detect astrophysical neutrinos through Cherenkov radiation. The full-scale detector will consist of approximately 1000 vertical strings, each equipped with 20 hybrid digital optical modules (hDOMs) containing both photomultiplier tubes (PMTs) and silicon photomultipliers (SiPMs) for comprehensive light detection. This paper presents a custom-designed digitization mainboard prototype for the hDOM, featuring simultaneous 32-channel PMT waveform digitization at 125 MS/s using commercial analog-to-digital converters and 56-channel high-precision time measurement through field-programmable gate array -implemented time-to-digital converters. The system demonstrates excellent performance in single photoelectron (PE) detection with clear pedestal separation, maintains linear response up to 240 PEs, and achieves sub-nanosecond timing resolution for PMT or SiPM pulse edges.

Paper Structure

This paper contains 7 sections, 12 figures, 1 table.

Table of Contents

  1. Introduction
  2. The Mainboard Design
  3. Performance
  4. Charge Measurement
  5. Timing measurement
  6. Summary
  7. Acknowledgement

Figures (12)

  • Figure 1: The overall and cross-sectional view of the TRIDENT prototype hDOM, including PMTs, SiPMs, the mainboard and other electronics boards. The hDOM is a pressure-resisted glass vessel with a diameter of 43 cm.
  • Figure 2: A typical SPE waveform from the PMT (Hamamatsu r14374) recorded by an oscilloscope with a 10 GS/s sampling rate. The PMT is applied with a high voltage of 1200V.
  • Figure 3: The overall design of the mainboard. Some of the main parts are: ADC (ADI AD9083), FPGA (Xilinx XC7k325T), DDR3 (Mircon MT41J128M16JT), Comparator (TI LTV3603), and PLL (TI LMK04610).
  • Figure 4: The top and bottom view of the digitization mainboard, which is a 16-layer PCB.
  • Figure 5: The signal conditioning circuit for ADCs. $R_{\mathrm{T}}$ is set to 50 $\Omega$ for impedance matching, R$=50 \Omega$, C$=120$ pF for pulse broadening. $V_\mathrm{offset}$ is for baseline leveling.
  • ...and 7 more figures