failed to produce a nuclear
detonation. The plan to use "JUMBO," however, was abandoned when the
scientists concluded that a fairly large nuclear explosion was
certain. The container remained on the ground near the shot-tower
during the detonation. Both the photographer and the monitor received
an estimated radiation exposure between 0.5 and 1 roentgen (1; 7).

The last party to "go in" on shot-day consisted of six men retrieving
neutron detectors. They entered the test area at 1430 hours. Three
of the men went to a point 730 meters south of ground zero to pull out
cables carrying neutron detectors located 550 meters south of ground
zero. The group wore protective clothing and respirators and spent
about 30 minutes in the area. The remaining three men drove as close
as 320 meters southwest of ground zero to retrieve neutron detectors.
They got out of their vehicle only once, at about 460 meters from
ground zero, and spent a total of about ten minutes making this trip
through the area. Each man's radiation exposure measured less than 1
roentgen (1).

Most of the soldiers of the evacuation detachment remained in their
bivouac area near Guard Post 2. According to a report written by the
detachment commander, a reinforced platoon was sent to the town of
Bingham, about 29 kilometers northeast of the test site, while offsite
radiological safety monitors surveyed the area. The evacuation
detachment was dismissed at 1300 hours on shot-day when it became
evident from offsite monitoring that evacuations would not be
undertaken. The detachment returned to LASL at 0400 on 17 July (15).

Two B-29 aircraft from Kirtland Field, Albuquerque, New Mexico,
participated in post-shot events. Their planned mission was to pass
over the test area shortly before the explosion to simulate a bomb
drop. After the TRINITY device had been detonated, the aircraft would
circle near ground zero, while the men onboard would measure the
atmospheric effects of the nuclear explosion. This would enable them
to determine whether a delivery aircraft would be endangered.
However, because of bad weather on shot-day, Dr. Oppenheimer canceled
the aircraft's flight in the ground zero area. Instead, the two
B-29s, each with 12 men onboard, flew along the perimeter of the
bombing range and observed the shot from a distance of 19 to 29
kilometers. Among those observers was a Navy captain who was also the
MED Chief of Ordnance (6; 12; 13).

2.3