Table 2.1 listo yields obtained by Program 10 for »..ots fired in the
Total thermal radiation measured on a
mean noon
Assuming atmospheric transmission of 63 per cent, which was
value on four
days, the corresponding thermal energy release from
the bomb was ine’. low thermal energy release (as seen from sea
level) 1g not un
tic because a large fraction of the early high temperature fireball radiation resides in the ultraviolet which is absorbed in the atEPG.
mosphere, particularly in the ozone layer. The duration of the thermal pulse
for deposition of 90 per cent of the incident energy was 175 msec.
Although time interval was measured, the value obtained is probably
low by about 10 per cent. The Teller light which provides time interval information originates at approximately 25 to 30 km above sea level, where
the main gamma ray flux is stopped. The slow apparent rise time of the
rather weak primary signal and unfavorable geometry related to the error
in burst position may have caused a delay in the recording of the first signal.
It {8 expected that a correction can be applied after further analysis.
The results of the experiments designed to attain the third and main
objective of the two programs were unfavorably affected by the burst location
error. Specifically, information on the very early development of the fireball
could not be obtained, since none of the collimated instrument channels covered
the true burst location. However the limb and so-called "envelope spaces"
between radii of 4 and 12 km yielded interesting time-resolved spectroscopic
data for times up to 5 min after the burst. They require much specific at~
tention and analysis. Generally one can say that the records will provide information on the fluorescent yield of gamma ray and x-ray excited air, on
the energy deposition in the air versus distance from source and thus in-
directly on source strength, on transition processes in the medium and low
energy deposition range, on gas temperatures and cooling rates, and about
early recombination processes.
air.
One record shows neutron flux effects on
Cursory inspection of the spectrograms and oscilloscope traces indi-
cates higher temperatures and a greater degree of ionization at a given radius
than expected and thus larger dimensions of the luminous fireball. This is
borne out by the observation that the emission by molecular species at 12 km
from burst center was of almost equal magnitude as the originally expected
signal from the 6-km location. Closer in, singly and doubly ionized atomic
species show up where the appearance of molecular species was expected.
On the other hand there are indications that the core area of the fireball was
less bright than predicted, indicating a higher rate of cooling by radiation
flow towards the edges.
The project plans to analyze high speed photographic data for radius
versus time and brightness versus time information. The combined information may suffice to check and revise current theory and provide a reasonably
comprehensive understanding of high altitude fireball phenomenology.
After failure to obtain early fireball core data from Teak shot, an at-
tempt was made to obtain such data from Orange, although one_had to exEo
pect very high reaction rates, namely of the order of at least a
Many instruments were therefore pointed at the burst location
and
set for highest possible time resolution. Unfortunately the shot was fired
under deteriorating weather conditions, resulting in a mean diffuse optical
transmission of only 6 per cent; the transmission for the collimated observation channels was even less.
Instrument and station performance was
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AFWL/HO
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