Measurements of the ion fraction and mobility of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>α</mml:mi><mml:mtext>−</mml:mtext></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>β</mml:mi></mml:mrow></mml:math>-decay products in liquid xenon using the EXO-200 detector

Alpha decays in the EXO-200 detector are used to measure the fraction of charged $^{218}\text{Po}$ and $^{214}\text{Bi}$ daughters created from $\ensuremath{\alpha}$ and $\ensuremath{\beta}$ decays, respectively. $^{222}\text{Rn} \ensuremath{\alpha}$ decays in liquid xenon (LXe) are found to produce $^{218}\text{Po}^{+}$ ions $50.3\ifmmode\pm\else\textpm\fi{}3.0%$ of the time, while the remainder of the $^{218}\text{Po}$ atoms are neutral. The fraction of $^{214}\text{Bi}^{+}$ from $^{214}\text{Pb} \ensuremath{\beta}$ decays in LXe is found to be $76.4\ifmmode\pm\else\textpm\fi{}5.7%$, inferred from the relative rates of $^{218}\text{Po}$ and $^{214}\text{Po} \ensuremath{\alpha}$ decays in the LXe. The average velocity of $^{218}\text{Po}$ ions is observed to decrease for longer drift times. Initially the ions have a mobility of $0.390\ifmmode\pm\else\textpm\fi{}0.006\phantom{\rule{4pt}{0ex}}{\text{cm}}^{2}/(\text{kV}\text{s})$, and at long drift times the mobility is $0.219\ifmmode\pm\else\textpm\fi{}0.004\phantom{\rule{4pt}{0ex}}{\text{cm}}^{2}/(\text{kV}\text{s})$. Time constants associated with the change in mobility during drift of the $^{218}\text{Po}^{+}$ ions are found to be proportional to the electron lifetime in the LXe.