Rapid extraction of short-lived isotopes from a buffer gas cell for use in gas-phase chemistry experiments. Part I: Off-line studies with 219Rn and 221Fr

To study the chemical properties of the heaviest elements, a fast and efficient stopping and extraction of the highly energetic residues from heavy ion fusion reactions into the chemistry setup is essential. Currently used techniques like Recoil Transfer Chambers (RTC) relying on gas flow extraction provide high efficiencies for chemically non-reactive volatile species, but operate at extraction times $t_{\text{extr}}$ of about 0.5 s or more. Buffer Gas Cells (BGC) with electric and Radio-Frequency (RF) fields offer much faster extraction times. Here, we demonstrate the successful coupling of a BGC to a gas chromatography setup as is used for studies of chemical properties of superheavy elements. Using ²²³Ra and ²²⁵Ac recoil ion sources providing ²¹⁹Rn and ²²¹Fr ions for off-line tests, an extraction time $t_{\text{extr}}$ = 55(4) ms and an extraction efficiency of 35(3)% were achieved for the non-reactive ²¹⁹Rn, while ²²¹Fr was retained. The results show a BGC-based setup to be suitable for gas-phase experiments with short-lived volatile transactinide elements like Cn and Fl with half-lives substantially below 1 s.