Lithium Flux Pressure Dependence

Because the background helium gas attenuates the incident alkali beam, absolute cross section mesurements require compensation for this pressure dependence. Scattering occurs primarily in the trap interior where the helium density is higher than outside the trap by a factor of ~35 as a result of the partial confinement of the trap structure. To account for the attenuated flux, the charge-exchange rates were obtained by measuring the C₆₀⁺ decay rate at different He pressures and extrapolating to the zero He pressure limit.