Stopping powers of gases for 40 MeV/u tellurium ions

The stopping powers of six gaseous media have been measured for incident 40 MeV/u Te-125 heavy ions. The energy losses of ions in various "thicknesses" of gas have been accurately determined. The gases were confined in a cell. The amount of matter traversed by the ions was determined from temperature and pressure measurements. The beam energy before and after slowing down were measured using the LISE magnetic spectrometer at GANIL. These experimental gas stopping powers are lower by about 10% than the corresponding tabulated values for solid media. This means that the gas-solid effect is still significant at 40 MeV/u for Te ions. The projectile effective charges derived from these measurements depend on the target atomic number, thus confirming the trend observed in previous experiments performed with lighter ions or at lower energies. (C) 2000 Elsevier Science B.V. All rights reserved.