Table 2.

Detection efficiencies of candidate parents (${\epsilon }_P$) and probabilities of delayed coincidences ($p_C$) evaluated from Monte Carlo simulations of bulk (b) and surface (s) crystal contaminations. For the surface contaminations, we sample the decay positions from an exponential distribution with $\lambda =10$ nm. Uncertainties are negligible due to the high Monte Carlo statistics

Isotope	Bulk	Surface
${}^{222}$Rn	${\epsilon }_P^b$ = 84.9%	${\epsilon }_P^s$ = 39.6%
${}^{218}$Po	$p_C^b$ = 96.5%	$p_C^s$ = 44.2%
${}^{224}$Ra	${\epsilon }_P^b$ = 79.5%	${\epsilon }_P^s$ = 36.1%
${}^{220}$Rn– ${}^{216}$Po	$p_C^b$ = 65.7%	$p_C^s$ = 14.3%