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Dust Loading on Air Samples for Alpha Activity



It is well known that nonradioactive dust on air samples, if not
corrected for, can cause underestimation of air concentrations of alpha
emitters.  Does anyone know of published data that gives curves or
equations for calculating correction factors for dust loading on alpha
air samples?  Of course one must know by some measurement the areal
density of the dust loading in terms of mg-cm-2 for a filter.  And, one
would know the alpha energy.  I would like a curve that, for a given
alpha energy and counting geometry, would tell me, for example, that a
dust loading of 1mg-cm2 would require multiplying the measured activity
by 2 to get the actual alpha activity on the filter paper.  Then there
is the complication of deposition of alpha activity as a function of
depth in the dust layer.  One could always make the conservative
assumption that all the alpha activity were under the entire thickness
of dust.  But, maybe, if the contaminated aerosol were assumed to be in
time uniformly deposited, the correction factor could take that into
account.  Thanks in advance.  Al Tschaeche xat@inel.gov