Ultrashort, Mev-Scale Laser-Plasma Positron Source For Positron Annihilation Lifetime Spectroscopy

Submicron 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 subnanometer 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 ultrashort 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 of the order of 103. Numerical simulations of the expected performance of a typical mJ-scale kHz laser demonstrate the possibility of generating MeV-scale narrow-band and ultrashort positron beams with a flux exceeding 105 positrons/s, of interest for fast volumetric scanning of materials at high resolution.