1.5
ESTIMATE OF MAXIMAL SKIN DOSE FROM ‘THE GROUND
In addition to the tofal body panima dose, the very sett ganimaand hagher enerpy beta
radiation from the plane source contributed to the skin dose, Further skin irradiition re:
sulted from local deposits of fallout material on the body surface itself. The latter is impos sibie to estimate, but the former may be roughly attempted as follows,
The bela dose rate in air ata height of 3 feet above the surface of an tnfinite phine contaminated with mixed 24-hour-old fission products is estimated to be about three times the
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DEPTH DOSE IN PHANTOM MAN
—O—— INITIAL RADIATION
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DEPTH (CM)
Fig. 1.5
Comparative Depth Doses ina Phantom Man of Initial Atomic Bomb Radiation and
Radiation from a Field of Fission Products
gamma dose. The midline gamma dose is approximately 60 per cent of the portion of the air
gamma dose due to 80 kv radiation or above. This portion in turn is estimated to be 90 per
cent of the gamma dose measuredin air by the instrument. Thus the dose at the surface of a
phantom exposed to mixed fission product radiation from an external plane source might be
expected to be 3,(0.6)(0.9) or about six times the midline dose, if both occur at 3 feet off the
ground. Such a depth dose measurementhas in fact been made experimentally at a previous