Design and optimization of a laser-PIXE beamline for material science applications

Abstract

Multi-MeV proton beams can be generated by irradiating thin solid foils with ultra-intense (>1018 W/cm2) short laser pulses. Several of their characteristics, such as high bunch charge and short pulse duration, make them a complementary alternative to conventional radio frequency-based accelerators. A potential material science application is the chemical analysis of cultural heritage (CH) artifacts. The complete chemistry of the bulk material (ceramics, metals) can be retrieved through sophisticated nuclear techniques such as particle-induced X-ray emission (PIXE). Recently, the use of laser-generated proton beams was introduced as diagnostics in material science (laser-PIXE or laser-driven PIXE): Coupling laser-generated proton sources to conventional beam steering devices successfully enhances the capture and transport of the laser-accelerated beam. This leads to a reduction of the high divergence and broad energy spread at the source. The design of our hybrid beamline is composed of an energy selector, followed by permanent quadrupole magnets aiming for better control and manipulation of the final proton beam parameters. This allows tailoring both, mean proton energy and spot sizes, yet keeping the system compact. We performed a theoretical study optimizing a beamline for laser-PIXE applications. Our design enables monochromatizing the beam and shaping its final spot size. We obtain spot sizes ranging between a fraction of mm up to cm scale at a fraction of nC proton charge per shot. These results pave the way for a versatile and tunable laser-PIXE at a multi-Hz repetition rate using modern commercially available laser systems.

Combined laser-based X-ray fluorescence and particle-induced X-ray emission for versatile multi-element analysis

“…The wide-range use of these laser-driven particle sources has triggered the construction of a series of laser facilities with dedicated laser-based beamlines (to cite a few of them: ALLS 1 in Canada, APOLLON 2 in France, VEGA 3 in Spain). Among the many applications, laser-based proton beams can be utilized for producing bright ultra-short neutron sources 4 , in medicine 5 , for picosecond metrology 6 , for stressing and testing materials 7 , 8 , and lately also in Ion Beam Analysis (IBA) 9 – 12 . Within the IBA techniques, we can name the Particle-Induced X-ray Emission (PIXE), a particle-based spectroscopy technique used for retrieving the elements of a material.…”

Novel Spectrometer Designs for Laser-Driven Ion Acceleration

“…The retrieved value of G resembles the typical gradient values employed for the design of laser-driven proton beamlines ( [26] and references therein). The distance to the detector plane L det is tuned in order to obtain the magnetic deflection for 100 MeV protons at 1 cm on the detector.…”

“…In conclusion, among the analyzed options, the quadrupole magnetic field profile is the most reliable, suitable, and feasible (easy to manufacture and assemble). In laserdriven proton acceleration, the use of quadrupole configurations, such as doublets and/or triplets, is not new because they have been implemented (as reported in refs [26,32]) downstream of the laser-plasma interaction point to manipulate and adapt laser proton sources for applications.…”

Novel Spectrometer Designs for Laser Driven Ion Acceleration

“…In conclusion, the quadrupolar magnetic field profile is the most reliable, suitable and feasible (easy to manufacture and assemble [43]) case, among the analyzed ones. In laser driven proton acceleration, the use of quadrupole (e.g., doublet and/or triplet) is not new because they have been implemented, as reported in refs [35,44], downstream laser-plasma interaction point for manipulating and adapting laser proton sources for applications.…”

“…The retrieved value of G resembles the typical gradient values employed for the design of laserdriven proton beamlines [35,36]. The distance to the detector plane L det is tuned in order to obtain the magnetic deflection for 100 MeV protons at 1 cm on the detector.…”