Quantitative elemental analysis of a specimen in air via external beam laser-driven particle-induced x-ray emission with a compact proton source

Particle-induced x-ray emission (PIXE) is a well-established ion-beam analysis technique, enabling quantitative measurement of the elemental composition of a sample surface under an ambient atmosphere with an external beam, which significantly simplifies the measurements, and is strictly necessary for those samples that cannot sustain a vacuum environment. Few-MeV electrostatic proton accelerators are used today in PIXE systems. We present here an external beam PIXE methodology based on a compact laser-driven proton accelerator. A 10-TW class ultrashort laser is used to generate a few-MeV proton beam, and a compact transport magnetic beamline is used to collect and transport the proton beam and to prevent unwanted fast electrons from reaching the sample. An x-ray CCD camera in single-photon detection mode is used to retrieve the spectrum of radiation emitted by the samples upon proton irradiation in air. Elemental composition analysis is performed and validated against standard energy-dispersive x-ray spectroscopy, demonstrating quantitative and accurate external beam PIXE analysis with compact laser-driven accelerators.