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Heavy ion beams generated by conventional RF-driven accelerators are commonly used in nuclear and particle physics. They have also found application in materials research, high energy-density physics and other domains. Heavy ion beams can also be generated by laser-driven ion accelerators, which are considered to be a promising alternative or supplement to RF-driven accelerators. However, to produce in these accelerators ion beams with the GeV or multi-GeV ion energies desired in most applications, multi-PW short-pulse laser drivers and ultra-relativistic laser intensities (~ 1023 W/cm2 or higher) are required. Multi-PW lasers capable of producing femtosecond pulses with ultra-relativistic intensities are currently being built, in particular, as part of the pan-European Extreme Light Infrastructure (ELI) project. The acceleration of heavy ions at ultra-relativistic laser intensities is, however, a poorly explored research field and requires extensive and detailed studies. In this paper, the results of numerical investigations of the acceleration of heavy (Pb) ions from a thin (0.1 um) lead target irradiated by a circularly polarized 30-fs, multi-PW laser pulse with intensity of 1023 W/cm2 are presented. The numerical simulations were performed using fully electromagnetic, multi-dimensional (2D3V) particle-in-cell code PICDOM, which includes, in particular, the dynamic ionization of the irradiated target and the accelerated ions. It was found that although the ion beam accelerated by the laser pulse contains more than 50 ion species with the charge state z ranging from z = 25 to z = 80, almost all of the energy of the beam (over 90% of the beam energy) is accumulated in ions with z = 72. Among all the accelerated ions, these ions have the highest both mean and peak energy, which values reach 14,6 GeV and 70,4 GeV, respectively. At a small distance from the target (<50 um), the intensity of the ion beam with z = 72 exceeds 1020 W/cm2 , and the duration of the ion pulse lies in the sub-picosecond range. Such intensities and durations of heavy ion beams are unachievable in currently operating RF-driven accelerators. The demonstrated laserdriven ion beams can thus open the door to new areas of research and applications not available for conventional accelerators.
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