and from location to location on the aircraft. The variations are indicated in Tables 3.1
and 3.2, which show the surface dose rates as measured by the T1B and by photographic
film. For tha film the maximum, average, and minimum dose rates are given. The
maxima and minima were measured through a densitometer cperture 0.1 mm in diameter.
The average value was derived from a densitometer aperture that encompassed nearly
the whuie area of the film. The intensity of radiation showed wide variations over very
small areas. For example, one film placed on the nose cf a B-57 about 2 hours after
Sice of fuselage of B-57B fust below
canopy. (Blurring near edges due to
poor cuntact with aircraft surface.)
Leading edge cf wir; of B-57B just
outboard of engine
Figure 3.1 Typical radioautographs, showing distribution of contamination
on amooth surfz.ces.
detonation showed a maximum of 400 rep/hr anda es :uciof 15 rep/hr.
value {s only 4 percer.t of the forimer.
7. latter
As might be expected, the vari:tion in dose rates from one shot to another was 4: -atest on impingement surfaces. This holds true for both T1B and film measurements.
3.2
COMPARISON OF MEASUREMENT METHODS
Dose-rate measurements with a T1B and psotographic film were made over as nearly
the same aree as possible. (It should be remembered that the sensitive area of the T1B
is approximaiely ten times that of the film.) Care was taken not to disturb the contarmi~
nation. The ratios between the two methods of measurement are shown in Tables 3.3
and 3.4. “he values shown are the average of a number of measurements. More comprehensive ‘ables are given in Appendix A (A.3 and A.4).
The val. .s shown in the columns headed “Film Max/T1B” and “Film Ave/T1B” are
the ratios c: the maximuin and average dose rates measured by the film to the T13 moas-
urement.
‘lhese r2tios are not beta-gamma ratios nor are they ratios of beta plus gamma
to gamma. They are ratios of the total surface dose rates as m-asured by two entirely
18
SECRET