It has been shown (Refererces 2, 3, and 7) that the papillary layer of skin where young
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skin ceils grow is the area where the greatest hazard exists and {s approximately 0.1 mm
beneati an outside layer of d:ad, inert skin, except on the palms and soles (where the
thickness of the dead skin may be 6.5 mm or more). By devising instrumce -ation with a
covering of no move than the thickness of this Inert layer of skin (approxiinntely 10 mg/em’)
overthe detecting element, one eliminates from his measurements only the radiation that
would no! be seen by the sensitive tissue of the body anyway. Difficulties engendered by
scattering are likewise minimizec by instrumentation that limita its measurements to a
very-thin layer and is surrounded by tissue-like material. Such a measurementgives
the highest anse rate one could expect for the most sensitiv: layer, that is, the maximum
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with gammas tn the irradiation of skin, {t was concluded in Reference 3 that in dealing
with unknown proportions of betas rnd gammas mixed togethsr, it 1s reascnahle {9 accept
the net ionization per unit volume as the total] beta-plus-gamma dose. Consequently, it
is not neceesary to differentiate between the two types of radiation in the empirical
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hazard. With reepect to the relative biological effectiveness (REE) of betas as compared
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measurements.
The work reported in Reference 6 undertook to determine the ratio between the greatest
tota] dose rate reaching the sensitive tissues o; the skin if contact is mace with a con-
taminated aircraft surface and the dose rate indicated by standard field survey instruments.
No atte1ipt was made to differentiate betwecn betas and gammas in determining this ratio,
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and the ratios so c'etermined are not beta-gamma ratios. The ratio was found to be about
a
90 to 1 on aircraft impact surfaces and less than 40 to 1 on aircraft surfaces other than
impact surfacoe. Some absorption studies were made trom which an apparent beta-gamma
ratio couic be inferred. These ratios agreed with those deter mined by the former tech-
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All of the measurements reported in Reference 6 were mace on aircraft whose contamination resulted from flying through the cloud of a detonation in the kiloton range.
The present project has undertaken to continue this work and to extend It to contamination
resulting from detonations in the megaton range.
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