Hi UBsorry for the delay - spent Sat organising an election...

Hi UB
sorry for the delay - spent Sat organising an election night party, Sunday recovering, this morning dealing with making alternative travel arrangements now that Tiger airways will not be operating from Alice till March...
here's a copy of the conference abstract (now in the public domain) that may answer most of your questions:
Branko Corner,2007, Radon enamometry in Uranium Exploration using activated charcoal: Namibian case studies, in Preview, Australian Society of Exploration Geophysics, 19th International Geophysical Conference & Exhibition, Conference Handbook, Abstracts, Dec 2007, Issue 131, pp71-72.
"In this study the implementation and refinement of the Radon-on-Activated-Charcoal (ROAC) technique, developed by the South African Atomic Energy Corp in the 1970's, is discussed. Case study results are presented from two areas in Namibia.
Radon, contained in ground air, migrates to surface as a result of the pumping action of diurnal pressure variations. It is absorbed onto activated charcoal in a catridge, fitted into the base of an inverted cup and buried in the ground. The technique (here termed RadonX) differs from alpha-sensitive systems in that it measures gamma radiation arising from the 214Bi and 214Pb daughter products of the absorbed radon. Thoron (220Rn), arising from Thorium that may be present, is not measured due to its very short half-life. The case study data are derived from an orientation survey over a known buried palaeo-channel of duricrust-hosted uranium, and from an exploration area potentially hosting uraniferous granites at depth. The RadonX survey shows:
*improved sensitivity compared to previous alpha-detection survey.
*good repeatibility. Some loss of sensitivity, due to possible large temperature variations between initial and fill-in surveys, is easily corrected for by repeat measurements.
*improved resolution with detailed grids, allowing accurate mapping of uranium mineralisation and positioning of boreholes.
*excellent penetration through residual or transported surficial cover. Given favourable porosity conditions, a depth of penetration of 80m or more has been achieved.
Deployment is rapid and cost effective."
From what I recall measurements using this method were in field.
Branko - Remote Exploration Services (PTY) Ltd, Swakopmund, Namibia.
The method is now commercialised. Not sure what EXT are going with.
hope this helps, sorry for any typos.
cheers