site had to be evacuated. Five radiological safety
monitors were assigned to this detachment. Ninety-four men of the
evacuation detachment belonged to Provisional Detachment Number 1,
Company "B," of the 9812th Technical Service Unit, Army Corps of
Engineers, from LASL. The identity of the remaining evacuation
personnel has not been documented (3; 4; 8; 10; 15).

With the exception of the shelter occupants (99 personnel) and
evacuation detachment (between 144 and 160 men), the number of
personnel at the test site at the time of detonation has not been
documented. Film badge records show that approximately 355 people
were at the test site at some time during 16 July. The shelter
occupants and 44 men of the evacuation detachment are on this list.
It has not been possible to pinpoint the location of many of the
remaining personnel. Some were at the Base Camp or on Compania Hill.
Since many of these people returned to the test site after shot-time
to work on experiments, their film badges registered exposures from
residual radioactivity on 16 July. Based on the documented personnel
totals, at least the following 263 individuals were at the test site
when the device was detonated (1; 4; 8-10; 13; 15):

o 99 shelter occupants at shelters 9,150 meters north, south, and west
of ground zero

o 144 to 160 officers and enlisted men of the evacuation detachment,
located 14 kilometers northwest of ground zero near Guard Post 2

o Five radiological safety monitors assigned to the evacuation
detachment to perform offsite monitoring of nearby towns and
residences

o One radiological safety monitor assigned to Guard Post 4

o Two military policemen at each of the seven guard posts (indicated
by photographs such as figures 1-3 and 1-4).

2.2 DETONATION AND POSTSHOT ACTIVITIES

Because of bad weather, the Project TRINITY director (Dr. Bainbridge)
delayed the detonation, which had been scheduled for 0400 hours. By
0445, however, the forecast was better, and shot-time was set for
0530. This gave the scientists 45 minutes to arm the device and
prepare the instruments in the shelters. The final countdown began at
0510, and the device was detonated at 0529:45 Mountain War Time from
the Control Point in the south shelter (3; 12).

No one was closer than 9,150 meters to ground zero at the time of the
detonation. With the exception of a few men holding the ropes of
barrage balloons or guiding cameras to follow the fireb