The general philosophy for the design, development, and implementation of the ion beam line in the ELI-Beamlines building is based on three key features: a user friendly approach, accurate monitoring and reliability of the accelerated ion beams, and flexibility for a future upgrade of the beam line. A complete beam line (ion source, in-vacuum ion beam transport, different dosimetric endpoints, and in-air sample irradiation end-station) will be available for users to enable them to apply laser-driven ion beams in multidisciplinary fields.
A 3D design of the ELIMAIA beam line in E4 is shown in the figure above. The ELIMAIA beam line is located in the northern part of experimental hall 4 (E4). The available laser beams are L3 and L4 (both at 1 PW power level) coming from the western wall. The ELIMAIA beam line consists of two main subsystems: Ion accelerator and ELIMED . An additional short pulse 0.1–1 J-level auxiliary beam, L-aux (for instance split from L3), will also be available for pump-probe user experiments.
The first subsystem is represented by a double plasma mirror vacuum chamber and a laser diagnostic section and main interaction vacuum chamber. In the plasma mirror chamber the laser beam is cleaned from sub-nanosecond pre-pulses. The beam then continues its propagation through the laser diagnostics section where various laser parameters, such as laser energy, pulse duration, contrast ratio, and wavefront, are measured. After a proper control of their properties the laser beams are sent into the interaction chamber and focused onto the targets by off-axis parabolic mirrors. The main proton/ion beam produced at the laser-target interaction point propagates from left to right and is sent into the ELIMED subsystem, which is represented by the in-vacuum ion beam transport and diagnostics, and by the in-air ion beam dosimetry and sample-irradiation sections. The accelerated ions are collected by a set of permanent magnet quadrupoles to be used for a preliminary focalization and for a rough energy selection of the laser-driven ion beams. The beam transport line will accommodate several diagnostic systems (high energy Thomson spectrometer, detector arrays for beam emittance measurements, time-of-flight detectors). Moreover, the accelerated proton/ion beam will have to be shaped in space and in energy according to the specific request coming from the user. A set of quadrupole magnets, focusing the accelerated particle beam (typically having a high angular divergence), and an energy selector system, selecting the required energy window, can be used to address this issue. The particle beam then enters the in-air ion beam dosimetry section where its properties are measured at different positions and further shaped, depending on the specific user application. Therefore, the dose released to the final sample (e.g., a radiobiological one) is monitored with relative and absolute dosimetric systems allowing real-time control of the delivered particle beam.
The aim of ELIMAIA will be to demonstrate that the overall cost of the standard acceleration facilities can be drastically reduced by using innovative compact approaches based on high power laser-matter interaction. In fact, the main goal of the ELIMAIA beamline is to provide stable, fully characterized, and tunable particle beams accelerated by PW-class lasers and to offer them to a broad national and international community of users for multidisciplinary applications, as well as fundamental science. An international scientific network, called ELIMED (ELI MEDical applications), that is particularly interested in future applications of laser-driven ions for hadrontherapy has already been established [ELIMED Workshop]. However, this is only one of the potential applications of the ELIMAIA beamline, which will be open to several proposals from a multidisciplinary user community. These proposals will be for areas such as non-conventional ion acceleration, radiobiology, time-resolved radiography of different materials, and beam-target nuclear reactions generating isotopes for positron emission tomography or producing high brilliance secondary radiation sources (e.g., neutrons and alpha-particles).
Typical user requirements
- Wide energy and fluence range
- Small energy spread (quasi-monoenergetic beams)
- Homogeneous transverse beam distribution
- Shot-to-shot stability (energy and fluence)
- Variable beam spot size
- Full beam control (fluence and dose) with < 5% error
- Possibility of in-air irradiation (e.g. bio-samples)
- Use of different ion species (H, He, Li, C)
What the users get
Ion Beam Features (PW)
Ion No./laser shot
>109 (0.1 nC) in 10% BW
>1010 (1 nC) in 10% BW
Ion Spot Size
Summary of main vacuum equipment, targets and diagnostics available at ELIMAIA
Target chamber size
10-6 - 10-5 mbar
Focusing optics (OAP)
f/1.5 (L3), f/3 or f/4 (L4-PW)
Estimated laser intensity
Thin foils (0.01-10 µm); metal/plastic tape + cryogenic H (5-100 µm)
Target delivery (1-10 Hz)
Translational tower; cryostat for solid H (ELISE); gas targets
Diagnostics (1-10 Hz)
Thomson parabola spectrometer; TOF detectors, CMOS/CCD cameras; X-ray pin diodes; optical interferometer; digital Storage Oscilloscope (> 1 GHz - 10 GS/s); ion beam transport devices; ion beam dosimeters (Faraday cup, ionization chamber, SEM)
Diagnostics (single shot)
Stacks of radiochromic films; nuclear track detectors
According to the state of the art in laser-driven ion acceleration, maximum proton energies of several tens of MeV have been experimentally achieved with a relatively high yield (1010-1012 protons/pulse). However, laser-accelerated ion beams are still not mature for several applications in which additional features, such as low divergence, monoenergeticity, spatial profile uniformity, or shot-to-shot stability, are essential. Nevertheless, new laser technologies that will soon be available, e.g. ELI Beamlines, will allow the scientific community to investigate new regimes that are very promising in terms of future use of laser-driven ion beams for various applications.