A High Precision Time Measurement Method Based on Frequency-domain Phase-Fitting for Nuclear Pulse Detection

TL;DR

This paper introduces a digital frequency-domain phase-fitting method for nuclear pulse timing, achieving sub-nanosecond precision and demonstrating its effectiveness through theoretical analysis, prototype implementation, and cosmic ray testing.

Contribution

The paper presents a novel high-precision time measurement technique based on frequency-domain phase-fitting, validated by a prototype and practical cosmic ray experiments.

Findings

Achieves 50 ps to 2.9 ps RMS precision under ideal conditions.

Demonstrates 1.7 ns RMS precision in cosmic ray tests.

Precision improves with increased pulse bandwidth.

Abstract

This paper proposes a high-precision time measurement method based on digital frequency-domain phase-fitting (DFPF) by using the digitized nuclear pulses. The averaging effect inherent in the frequency-domain cross-correlation and phase-fitting processes effectively minimizes measurement errors, thereby ensuring high precision and resolution in time interval measurements. In this paper, the theory of this DFPF-based time measurement method is analyzed, and an electronics prototype is designed to validate the feasibility of the proposed method by utilizing ADCs for pulse digitization and an FPGA for phase fitting implementation. The test results indicate that, under ideal conditions with a signal-to-noise ratio (SNR) of 64 dB, this method achieves time measurement precisions of 50 ps, 18 ps, and 2.9 ps RMS, corresponding to different Gaussian pulse widths and sampling rates of 118 ns at 40 MSPS, 10 ns at 100 MSPS, and 3 ns at 500 MSPS, respectively. The precision improves with increasing pulse bandwidth. Furthermore, in practical cosmic ray tests, the method achieved favorable timing performance with a precision of 1.7 ns RMS. These results demonstrate that this proposed method has the potential to be a high-precision time measurement for particle detection and is equally applicable to other advanced time measurement scenarios.