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.

中文翻译：

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用于材料科学应用的激光 PIXE 光束线的设计和优化

多 MeV 质子束可以通过用超强 (>1018 W/cm2) 短激光脉冲照射薄固体箔来产生。它们的几个特性，例如高束电荷和短脉冲持续时间，使它们成为传统基于射频的加速器的补充替代品。一个潜在的材料科学应用是文化遗产 (CH) 文物的化学分析。大块材料（陶瓷、金属）的完整化学成分可以通过复杂的核技术（如粒子诱导 X 射线发射 (PIXE)）进行恢复。最近，激光生成质子束的使用被引入作为材料科学的诊断（激光 PIXE 或激光驱动 PIXE）：将激光产生的质子源与传统的光束转向装置耦合，成功地增强了激光加速光束的捕获和传输。这导致源头处的高发散和广泛的能量扩散减少。我们的混合光束线的设计由能量选择器和永磁四极磁铁组成，旨在更好地控制和操纵最终质子束参数。这允许定制平均质子能量和光斑尺寸，同时保持系统紧凑。我们进行了一项理论研究，优化了激光 PIXE 应用的光束线。我们的设计使光束单色化并塑造其最终光斑尺寸。我们获得的光斑尺寸范围从几分之一毫米到厘米级，每次发射的 nC 质子电荷的一小部分。