Experiments on the interaction of fast heavy ions with a laser-plasma target

We have experimentally investigated the stopping power of a laser-ablated carbon plasma tested with a 225 keV/u oxygen beam. A dense plasma target was produced by irradiation of a graphite rod with a Q-switched Nd–glass laser. We have developed a diagnostics system for the target plasma using laser interferometry. The motion of the fringes was observed by a streak camera in order to obtain time-dependent electron density profiles. The maximum areal electron density of the carbon plasma reached nel=1×1018 cm−2. For the measurement of the energy loss of ions in the target, we developed a time-resolved magnetic spectrometer system with a plastic scintillator and an MCP. Using a streak camera we measured the shift of the beam spot on the MCP. The stopping power observed 40 ns after the laser was fired was 15 MeV/(mg/cm2). This value is enhanced by 50% compared to that in the cold equivalent.