## 2 Elimaia Diagnostics
### TOF: Description, Test, and Results  
Energy spectrum, energy spread, angular distribution, and flux of the accelerated ion beam must be measured in real-time using very accurate methods. A specific on-line diagnostics system has been developed based on the TOF technique using diamond (polycrystalline and single crystal) and silicon carbide detectors. The TOF technique has been used extensively so far for the diagnosis of laser-accelerated proton and ion beams at low energy (up to ten's MeV) and with low repetition rate laser systems [18; 19]. Coupling such a technique with detectors as Faraday cups (FCs), ion collectors (ICs), or semiconductor-like detectors as diamond and silicon carbide ones, the biggest advantage of the TOF diagnostics is the capability to provide real-time measurement of the beam characteristics as energy cut-offs, distributions, and current and shot-to-shot reproducibility up to a repetition rate of 10 Hz. Nevertheless, the detection of intense ion/proton beams up to 100 MeV level, expected to be generated at ELIMAIA, with TOF method requires the use of fast detectors to disentangle the high-energy component of the beam. A number of features, such as their radiation hardness, make diamond and silicon carbide detectors particularly attractive in harsh plasma environment, where many particles per bunch (up to 10\({}^{9}\)) ionize the detector simultaneously. In fact, diamond detectors can be used in TOF geometry for ion measurements on a bunch-to-bunch basis at high laser repetition rates, or in particle counting mode, typically in particle physics for beam monitoring. The main advantages of these detectors compared with FCs or ICs are their large band-gap, which cuts out of the high intensity visible and UV light emission from the plasma and their fast response to detect fast particles in TOF. These features coupled with high signal-to-noise ratio, typical of diamond and silicon carbide detectors, make these detectors more attractive than other devices, such as FCs or ICs, for timing measurement of high-pulsed and high-energy ion beams [20; 21]. The ELIMAIA TOF-based diagnostics system will be provided with at least three diamond detectors: one close to the interaction area (about 1 m from the target) as a part of the ion accelerator section and two detectors along the ELIMED transport and selection section (one will be placed about 2 m downstream the target, after the PMQ system and just before the energy selector injection point, and the other one will be placed about 9 m downstream the target, after the energy selection system). The TOF detector closer to the target, coupled with the TPS, will be used to characterize the particle beam (i.e., total ion current, shot to shot reproducibility) generated during the ion source optimization and, thanks to the diamond detector response, it will also allow to measure proton cut-off energies up to 50 MeV with an acceptable resolution even at such short distance from the target. The two detectors installed along the ELIMED section will allow one to monitor online the stability, the beam flux, and the energy spectrum of the proton beam focused by the PMQ system just before the selection in energy, and to measure the energy bandwidth and the flux of the proton beam selected shot to shot in real-time. The online beam parameter characterization given by the TOF measurement along the ELIMED transport and selection section will provide crucial information for transport optimization, also giving the possibility to tune \"real-time\" and adjust the PMQs and the ESS parameters according to the required beam specification. The ELIMAIA TOF diagnostics consists of two single crystal diamond detectors, 140 \(\upmu\)m and 500 \(\upmu\)m thick, respectively, and a 100 \(\upmu\)m thick polycrystalline diamond detector supplied by the CIVIDEC company.