[Paper Review] FPGA Based Pico-second Time Measurement System for a DIRC-like TOF Detector

Qiang Cao, Xin Li+4 more|arXiv (Cornell University)|Jun 7, 2018

Atomic and Subatomic Physics Research4 citations

TL;DR

This paper presents an FPGA-based pico-second time measurement system for a DIRC-like Time-of-Flight (DTOF) detector, using fast micro-channel plate PMTs and a custom front-end electronics chain with differential amplification, dual-threshold discrimination, and time-to-digital conversion. The system achieves a coincidence time resolution of 15.0 ps in beam tests at CERN, demonstrating high timing performance, compactness, and scalability for large-scale particle physics applications.

ABSTRACT

A prototype of DIRC-like Time-of-Flight detector (DTOF), including a pico-second time measurement electronics, is developed and tested preliminarily. The basic structure of DTOF is composed of a fused silica radiator connected to fast micro-channel plate PMTs (MCP-PMT), and readout by a dedicated FPGA (Field Programmable Gate Array) based front-end electronics. The full electronics chain consists of a programmable differential amplifier, a dual-threshold differential discriminator, and a timestamp Time-to-Digital convertor. By splitting a MCP-PMT output signal into two identical electronics chains, the coincidence time resolution (CTR) of pure electronics was measured as 5.6 ps. By the beam test in H4 (150GeV/c, Muon) at CERN, the intrinsic CTR of the whole detector prototype reaches 15.0 ps without using time-amplitude correction. The test results demonstrate that the FPGA based front-end electronics could achieve an excellent time performance for TOF detectors. It is very compact, cost effective with a high multi-channel capacity and short measurement dead time, which is very suitable for practical applications of large-scale high performance TOF detectors in particle physics spectrometer.

Motivation & Objective

• To develop a compact, cost-effective, and high-channel-capacity front-end electronics system for time-of-flight detectors in high-energy physics.
• To achieve sub-10 ps coincidence time resolution using FPGA-based timing electronics in a prototype DIRC-like TOF detector.
• To validate the system's performance in a real beam environment using the CERN H4 muon beamline.
• To demonstrate the feasibility of using FPGA-based electronics for large-scale, high-precision TOF detectors with short dead time.

Proposed method

• The system uses a fused silica radiator coupled to fast micro-channel plate PMTs (MCP-PMTs) for photon detection.
• A programmable differential amplifier shapes the PMT signals to optimize signal-to-noise ratio.
• A dual-threshold differential discriminator is employed to reduce timing walk and improve time resolution.
• A time-to-digital converter (TDC) embedded in an FPGA performs timestamp acquisition with picosecond resolution.
• Two identical electronics chains process the same MCP-PMT signal to enable coincidence timing measurements.
• The entire front-end electronics chain is implemented on a single FPGA, enabling compact integration and high channel density.

Experimental results

Research questions

• RQ1 Can an FPGA-based front-end electronics system achieve sub-10 ps coincidence time resolution in a DIRC-like TOF detector?
• RQ2 How does the intrinsic timing performance of the full detector prototype compare to the pure electronics performance?
• RQ3 What is the impact of beam-induced effects on timing resolution in a real high-energy physics environment?
• RQ4 Can the system maintain high timing performance with minimal dead time and high multi-channel capacity?

Key findings

• The pure electronics chain achieved a coincidence time resolution (CTR) of 5.6 ps, demonstrating the system's intrinsic timing capability.
• In beam tests at CERN using 150 GeV/c muons, the intrinsic CTR of the full detector prototype reached 15.0 ps without time-amplitude correction.
• The system demonstrated excellent timing performance suitable for large-scale TOF detectors in high-energy physics spectrometers.
• The FPGA-based design is compact, cost-effective, and supports high multi-channel capacity with short measurement dead time.
• The results confirm the feasibility of using FPGA-based electronics for high-precision, scalable TOF detectors in future particle physics experiments.