of this area found no gamma
intensities higher than 0.02 R/h (1).

Gamma radiation levels at and around ground zero were much higher than
in other onsite areas because of induced activity in the soil.
Twenty-four hours after the detonation, the gamma intensity at ground
zero was estimated to be 600 to 700 R/h. This estimate was based on
data provided by the tank crew that drove to ground zero to obtain
soil samples. The intensity decreased to about 2 R/h at 725 meters
from ground zero. Gamma intensities of 0.1 R/h or more were confined
within a circular area extending about 1,100 meters from ground zero
(except in areas of fallout). One week after the shot, the gamma
intensity at ground zero was about 45 R/h. After 30 days, intensities
at ground zero had decreased to 15 R/h, and intensities of 0.1 R/h or
more were not encountered beyond about 365 meters from ground zero.
Gamma intensities of 3 to 10 R/h were found at ground zero three
months after the detonation (1; 19).

3.3 OFFSITE MONITORING GROUP

Four two-man teams and one five-man team supervised by the chief
offsite monitor constituted the Offsite Monitoring Group. Before the
detonation, the four two-man teams established monitoring posts in
towns outside the test area. These towns were Nogal, Roswell, Fort
Sumner, and Socorro, all in New Mexico. The five-man team remained at
Guard Post 2 to assist in evacuation of nearby residences if the
TRINITY cloud drifted in that direction. These residences, the Fite
house and the homes in the town of Tokay, were 24 and 32 kilometers
northwest of ground zero, respectively. Since the cloud drifted to
the northeast, evacuation was not required. All offsite monitoring
teams were in radio or telephone contact with personnel at the Base
Camp (11).

Offsite monitoring teams in areas northeast of ground zero encountered
gamma readings ranging from 1.5 to 15 R/h two to four hours after the
detonation. Three hours after the detonation, surveys taken in
Bingham, New Mexico (located 30 kilometers northeast of ground zero)
found gamma intensities of about 1.5 R/h. Radiation readings at the
town of White, nine kilometers southeast of Bingham, were 6.5 R/h
three hours after the detonation and 2.5 R/h two hours later. Another
team monitoring in a canyon 11 kilometers east of Bingham found a
gamma intensity of about 15 R/h. Five hours later, the intensity had
decreased to 3.8 R/h. It was estimated that peak intensiti