Experimental results for change of H and Li ions stopping in metal foils with temperature

We present experimental results and a preliminary analysis of the energy loss for approximately 2 MeV/amu energy H and Li ions in metal foils. The experiments were performed in transmission geometry with the detector aligned with the beam. We selected Ni with special emphasis on the ferro-paramagnetic phase transition and for reference Ta foils which is free of phase transitions in the range from the room temperature to ca. 700 °C. The analysis of the results was performed under assumption that the stopping cross section per atom remains independent of the temperature. A serious discrepancy between the measured energy loss and the expected results was found. An enhanced transparency of the foil for high-energy fraction of the beam was also noticed. We associated these effects with structural transformation of the foils and with change of their electronic structure.