Charge-state distribution measurements of U238 and Xe136 at 11MeV/nucleon using gas charge stripper

Abstract

The charge-state distributions and equilibrium charge states of uranium (U238) and xenon (Xe136) ions at 11MeV/nucleon were determined using a gas charge stripper. A differential pumping system facilitated the increase of the nitrogen gas thickness up to 1.3mg/cm2, which is sufficient for the most probable charge state to attain equilibrium. The charge states of U238 attain equilibrium at 56.0, 56.6, and 55.7 in N2, Ar, and CO2 media with thicknesses of 125, 79, and 126μg/cm2, respectively, while those of Xe136 attain equilibrium at 40.5, 40.1, and 40.3 in N2, Ar, and CO2 media with thicknesses of 163, 95, and 139μg/cm2, respectively. The equilibrium charge states of Xe136 are acceptable for acceleration by the subsequent cyclotron. The measured data of U238 were used to devise an empirical formula for the prediction of the equilibrium charge state in gaseous media over the energy region of 0.01-60MeV/nucleon. The equilibrium charge state of Xe136 as predicted by the devised formula is in good agreement with the data. © 2010 The American Physical Society.