Measurements of charge state distributions of 0.74 and 1.4 MeV/u heavy ions passing through dilute gases

Abstract

In many modern heavy-ion accelerator facilities, gas strippers are used to increase the projectile charge state for improving the acceleration efficiency of ion beams to higher energies. For this application, the knowledge on the behavior of charge state distributions of heavy-ions after passing through dilute gases is of special interest. Charge state distributions of uranium ($^{238}\mathrm{U}$), bismuth ($^{209}\mathrm{Bi}$), titanium ($^{50}\mathrm{Ti}$), and argon ($^{40}\mathrm{Ar}$) ion beams with energies of $0.74\text{ }\mathrm{MeV}/\mathrm{u}$ and $1.4\text{ }\mathrm{MeV}/\mathrm{u}$ after passing through hydrogen (${\mathrm{H}}_{2}$), helium (He), carbon dioxide (${\mathrm{CO}}_{2}$), nitrogen (${\mathrm{N}}_{2}$), oxygen (${\mathrm{O}}_{2}$), neon (Ne), and argon (Ar) gases were measured. Gas stripper target thicknesses up to $100\text{ }\text{ }\ensuremath{\mu}\mathrm{g}/{\mathrm{cm}}^{2}$ were applied. The observed behavior of the charge state distributions, including their width and mean charge state, are discussed. The measurements show the highest equilibrium charge state at $1.4\text{ }\mathrm{MeV}/\mathrm{u}$ for $^{238}\mathrm{U}$ on ${\mathrm{H}}_{2}$ gas of $29.2\ifmmode\pm\else\textpm\fi{}1.2$. Narrow charge state distributions are observed for $^{238}\mathrm{U}$ and $^{209}\mathrm{Bi}$ on ${\mathrm{H}}_{2}$ and He gas, which are highly beneficial, e.g., for the production of beams of high intensities in accelerators.