“…For the stopping volumes of 0.5-2 Â 10 5 cm 3 [11,16,25,26] dictated by the high energies and emittances at in-flight separators, considering practical limits to the gas flow through the exithole that can be handled, gas flow is too slow for efficient ion extraction of short-lived isotopes. For example an exit-hole diameter of 1 mm, having a conductance of 0.45 l/s for helium gas at room temperature, combined with the stopping volume of 190 l for the cryogenic stopping cell described here, gives a helium gas refresh rate of once per 7 min.…”