## 1 Introduction  
Ion acceleration driven by high-intensity laser pulses is attracting an impressive and steadily increasing research effort. Experiments over the past two decades have demonstrated the generation of several tens of MeV proton and ion beams with unique properties, which have stimulated interest in many innovative applications. Efficient energy boost of the laser-accelerated ions is critical for their applications in biomedical and clinical research. Achievable proton energies continue to rise, with currently the highest energies of the order of hundred MeV, as recently reported in the literature [1], allowing access to the medical therapy energy window in protontherapy (60-250 MeV) [2]. Hadron therapy is currently considered one of the most advanced and precise external radiotherapy techniques for tumour treatment [3]. Hadrons show several advantages with respect to more conventional radiation sources, such as electrons, and gamma- and X-rays, in terms of both spatial precision of the released dose and biological effectiveness [4]. Nevertheless, current acceleration techniques for protons and ions demand high financial investments and running costs associated with large-scale accelerator facilities, ion beam delivery, and radiation shielding systems, thus preventing their widespread use in clinical application. On the other hand, ion beams accelerated by high-intensity lasers are very promising because they are produced in an extremely compact \"plasma accelerator\" in comparison with conventional accelerators, thus having huge potential in terms of overall cost of a laser-based accelerator facility. Such particle beams are, typically, accelerated over micrometer range distances and have no limitation in terms of ion species, different to conventional accelerators. These characteristics make such an approach extremely appealing both for applications and for new basic science to be explored [5; 6]. A more compact laser-based therapy unit could provide particle therapy to a much broader range of patients [7; 8] and, moreover, would offer the advantage of an integrated system able to provide different types of radiations from the same source (laser) for different purposes: (i) performing treatments with different types of radiation sources (protons, heavier ions, electrons, X/gamma-rays, and neutrons) to explore new combined modalities; and (ii) coupling treatment and imaging for monitoring the tumour position without adding additional devices. Recently a unique user beamline ELIMAIA (ELI (Extreme Light Infrastructure) multidisciplinary applications of laser-ion acceleration) [9] has been installed at the ELI-Beamlines international user facility (Czech Republic). Its main goal is to deliver laser driven proton/ion beams both for basic laser-plasma acceleration physics and for multidisciplinary user applications, especially in the field of hadron-therapy or biomedical research [10]. The ELIMAIA beamline has been designed and developed at the Institute of Physics of the Academy of Science of the Czech Republic (IoP-ASCR) in Prague and at the National Laboratories of Southern Italy of the National Institute for Nuclear Physics (LNS-INFN) in Catania (Italy). ELIMAIA consists of two main subsystems: the ion acceleration platform and the ELIMED (ELI medical and multidisciplinary applications) user application line (ion beam transport and dosimetry). A 3D rendering of the ELIMAIA beamline (Ion Accelerator + ELIMED) is shown in Figure 1. A complete description of ELIMAIA, including ELIMED, is reported in the literature [9]. The ion acceleration platform consists of a double plasma mirror chamber; a local laser diagnostics station; and an interaction chamber providing laser beam transport, pulse treatment, ion source generation, and in-situ ion and plasma characterization.