Project Trinity 1945-1946 | Page 9

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 fireball as it ascended, all shelter personnel were in or behind the shelters. Some left the shelters after the initial flash to view the fireball. As a precautionary measure, they had been advised to lie on the ground before the blast wave arrived. Project personnel located beyond the shelters, such as at the Base Camp and on Compania Hill, were also instructed to lie on the ground or in a depression until the blast wave had passed (1). However, the blast wave at these locations was not as strong as had been expected.
In order to prevent eye damage, Dr. Bainbridge ordered the distribution of welder's filter glass. Because it was not known exactly how the flash might affect eyesight, it was suggested that direct viewing of the fireball not be attempted even with this protection. The recommended procedure was to face away from ground zero and watch the hills or sky until the fireball illuminated the area. Then, after the initial flash had passed, one could turn around and view the fireball through the filter glass. Despite these well-publicized instructions, two participants did not take precautions. They were temporarily blinded by the intense flash but experienced no permanent vision impairment (1; 17).
People as far away as Santa Fe and El Paso saw the brilliant light of the detonation. Windows rattled in the areas immediately surrounding the test site, waking sleeping ranchers and townspeople. To dispel any rumors that might compromise the security of Project TRINITY, the Government announced that an Army munitions dump had exploded. However, immediately after the destruction of Hiroshima, the Government revealed to the public what had actually occurred in the New Mexico desert (12; 13).
Immediately after the shot, Medical Group personnel began the radiological monitoring activities described in section 3.1.2. At 0815, when most of the monitoring activities were completed, preparations began for entrance into the ground zero area. To regulate entry into the area, a "Going-in Board" was established, consisting of Dr. Bainbridge, the Chief of the Medical Group, and a special scientific consultant. Its purpose was to determine whether a party had a valid reason for entering the ground zero area. The board functioned for three days.
Military police at Guard Post 4 and at three roadblocks set up along Broadway controlled entry into the area. Guard Posts 3, 5, 6, and 7 were within 3,000 meters of ground zero and thus remained unmanned. At the south shelter, the Medical Group set up a "going-in" station where personnel were required to stop to put on protective clothing (coveralls, booties, caps, and cotton gloves) and pick up monitoring equipment before entering the ground zero area. Since it was not known how much radioactive material might be suspended in the air, all personnel entering the ground zero area wore complete protective covering and respirators for the first three days after the detonation. Figure 2-6 shows two Project TRINITY personnel wearing protective clothing (1).
On the day of the shot, five parties entered the ground zero area. One party consisted of eight