eTee SLY
The ccmplete absence of bumps and wiggles in the nolse-monitoring trace showed th: t the
instrument was well shielded from spurious signals, and therefore all variations in the beta
trace could be attributed to bona fide material-density changes.
In view of the apparent absence of thermal dust, the initial rise in density (rise time =
0.003 sec) was interpreted as being caused only by an increase in density of shocked air. The
measured density of shocked material (air) to unshocked material (air), p/p, = 1.53, would
give, using the Rankine-Hugoniot relation
Pe
Po
~(y+ yee (y-1)
(y-1) 2
—-y +1)
De
and
y = 1.40
a peak overpressure of P—P, = 12.4 psi at Station 690.02, which was 23,219 ft from ground zero.
Unless there is so much turbulence as to prevent positive identification of blast arrival, it
appears possible to calculate p/p»), and hence P/P,, due to air shock alone by subtracting the
ro
SEER,oete precE2cudhy8
wee
~ MCDUY Gyeet eRe QEoT freangs eee ee
increase in density due to thermal dust, which is recorded on the film.
28
RESTRICTED DATA (BP SECURITY INFORMATION