## 3 Elements of the Beam Line Prototype
### On-line Beam Diagnostics and Dosimetry  
The pulse properties of optically accelerated ion beams differ significantly from those commonly provided by conventional accelerators in pulse duration, peak current and correspondingly pulse dose rate and energy spectrum. Thus, among obvious properties, such as operational stability, the development of innovative techniques for diagnostics and dosimetry represents a crucial step towards multidisciplinary applications of laser-driven beams with the required uncertainty. Typical laser-driven beam specifications report proton burst duration of the order of 0.1-1 ns, with intensity ranging from 10\({}^{10}\) to 10\({}^{12}\) p/burst. Therefore, the detectors developed for the on-line beam monitoring systems and for the relative dosimetry have to be dose-rate independent, in order to be able to measure very intense and short pulses without saturation effects and suitable to operate in presence of a strong electromagnetic pulse (EMP). Different alternative approaches will be followed in the development of detectors for on-line non-invasive beam current monitoring. Different diagnostics detectors will be placed, in particular, after the focusing and the selection systems. A detector, based on the well-known pepper pot method, will be specifically designed and optimized for single shot emittance measurement of the laser-driven proton beam after the PMQs system. On the other hand, particle identification and fluence/current measurements will be performed using Silicon Carbide (SiC), CVD diamond detectors and secondary particle emission detectors (SEM), based on the secondary electron emission from a thin metallic foil hit by ion beams. These radiation-hard detectors, suitable to work in harsh radiation environments, will be used in ToF mode for plasma ion intensity and energy distribution measurements in the energy range between few MeV/n up to 60 MeV/n. They will be placed at different distances from the target along the beam-line, in particular, after the PMQs system and after the energy selection device at the end of the in-vacuum section of the beam-line. The high temporal resolution and the fast response of SiC and CVD detectors, together with the high signal-to-noise ratio characteristics, already tested in the previous experimental campaign at PALS and at TARANIS laser facilities, will allow determining the energy of the identified selected ions with resolution of about 20% for the maximum energy selected (_i.e._ 60 MeV/n). So far, no protocol for absolute dosimetry for optically accelerated ion beams has been established. In order to fulfill this task, a reliable and accurate dosimetric characterization of laser-driven charged particle beams has to be performed. Therefore, devices and procedures to develop a calibration method for absolute dose evaluation have to be implemented. The device proposed to perform absolute dose measurements will consist of a Faraday Cup (FC) specifically designed to measure the beam charge with high accuracy and extract the absolute dose for pulsed laser-driven beams. Indeed, thanks to the linear response with respect to the beam intensity and the dose rate independent signal, a FC is expected to allow charge collection with high level of accuracy, also in case of high pulsed and extremely intense beams. A FC prototype [27] for absolute dosimetry with high-pulsed ion beams has been recently designed and realized at the INFN-LNS within the ELIMED project. The FC technical design has been inspired to similar detectors already developed for ion-beam dosimetry [22,28], adopting innovative geometrical solutions in order to further improve the overall charge collection efficiency [29]. In the absolute dose measurement using a FC, the main uncertainty sources are related to the precise measurements of the total charge carried by the beam, of the proton beam energy spectrum and of theeffective beam area, needed to extract the fluence distribution. Each of these quantities has to be separately and accurately evaluated.