Ultra-short, MeV-scale laser-plasma positron source for positron annihilation lifetime spectroscopy

TL;DR

This paper demonstrates a novel laser-driven method to generate ultra-short, MeV-scale positron beams with high flux, enabling advanced volumetric defect detection in materials beyond current surface-limited techniques.

Contribution

It introduces a new laser-based system capable of producing high-energy, narrow-band positron beams suitable for high-resolution, volumetric material analysis.

Findings

Positron beams with energies from 500 keV to 2 MeV generated experimentally.

Numerical simulations show flux exceeding 10^5 positrons/sec at kHz repetition rates.

Potential for high-resolution, volumetric defect detection in materials.

Abstract

Sub-micron defects represent a well-known fundamental problem in manufacturing since they can significantly affect performance and lifetime of virtually any high-value component. Positron annihilation lifetime spectroscopy is arguably the only established method capable of detecting defects down to the sub-nanometer scale but, to date, it only works for surface studies, and with limited resolution. Here, we experimentally and numerically show that laser-driven systems can overcome these well-known limitations, by generating ultra-short positron beams with a kinetic energy tuneable from 500 keV up to 2 MeV and a number of positrons per shot in a 50 keV energy slice \color{black} of the order of $10^3$. Numerical simulations of the expected performance of a typical mJ-scale kHz laser demonstrate the possibility of generating MeV-scale narrow-band and ultra-short positron beams with a flux exceeding $10^5$ positrons/s, of interest for fast volumetric scanning of materials at high resolution.