Drift time calibration of the ultra-low material budget GEM-based TPC for MIXE

TL;DR

This paper presents a calibration method for the drift time in a GEM-based TPC used in the MIXE technique, enhancing depth-resolved elemental analysis with high precision.

Contribution

It introduces a novel drift time calibration approach using a fiber detector and SiPM, improving spatial accuracy in the TPC for MIXE applications.

Findings

Achieved permille-level drift velocity calibration accuracy.

Enhanced depth resolution in elemental analysis.

Validated the calibration method with experimental data.

Abstract

Muon-Induced X-ray Emission (MIXE) is a non-destructive analytical technique that leverages negative muons to probe elemental and isotopic compositions by detecting characteristic muonic X-rays emitted during atomic cascades and gamma rays from nuclear capture processes. By controlling the muon beam momentum, MIXE enables depth-resolved analysis, spanning microns to centimeters, making it ideal for studying compositional variations in fragile, valuable, or operando samples. To enhance its capabilities, we integrated a twin Time Projection Chamber (TPC) tracker with Gas Electron Multiplier (GEM) amplification stages, allowing precise measurement of muon trajectories. A custom-built fiber detector with scintillating fibers and a Silicon Photomultiplier (SiPM) provides permille-level accuracy in drift velocity calibration, essential for accurate spatial reconstruction. This advanced setup correlates muon stopping points with X-ray emissions, paving the way towards element-sensitive imaging and establishing MIXE as a unique tool for high-resolution, depth-specific elemental analysis across diverse scientific applications.