High-Resolution Timing for Vertex-Reconstructed Muon-Spin Spectroscopy Using Plastic Scintillators and MuTRiG

TL;DR

This paper introduces a new detector system combining plastic scintillators and silicon pixel detectors with MuTRiG ASIC to significantly improve timing resolution in vertex-reconstructed muon-spin spectroscopy, enabling measurements at higher frequencies.

Contribution

The integration of plastic scintillators with MuTRiG ASIC into vx-μSR provides high temporal resolution and high-rate capability, surpassing previous silicon-only systems.

Findings

Achieved sub-300 ps timing resolution after correction.

Resolved precession frequencies beyond 50 MHz.

Demonstrated stable operation in vacuum environment.

Abstract

Vertex-reconstructed muon-spin spectroscopy (vx-{\mu}SR) based on silicon pixel detectors has recently demonstrated unprecedented lateral resolution and operation at muon stop rates exceeding 400 kHz. However, the intrinsic timing resolution of current silicon pixel detector technology limits the accessible frequency range and restricts {\mu}SR measurements with fast relaxation rates. In this work, we report on the integration of plastic scintillator detectors (PSD) read out with the MuTRiG ASIC into the MuSiP vx-{\mu}SR spectrometer. This complements the spatial resolution achieved by using silicon pixel detectors with high-precision timing information for incoming muons and decay positrons. We demonstrate stable operation of MuTRiG in vacuum and achieve sub-300 ps time resolution after time-walk correction. Standard transverse-field {\mu}SR measurements on a SiO$_2$ sample confirm that the combined MuTRiG-PSD system resolves precession frequencies beyond 50 MHz, far exceeding the capabilities of silicon pixel detectors alone. These results establish a viable and scalable path towards high-rate, high-resolution {\mu}SR with both excellent spatial and temporal performance.