ttan Engineer District
Manhattan Project
Personnel Dosimetry
Radiation Exposure
Nuclear Weapons Testing
20. ABSTRACT: This report describes the activities of an estimated
1,000 personnel, both military and civilian, in Project TRINITY, which
culminated in detonation of the first nuclear device, in New Mexico in
1945. Scientific and diagnostic experiments to evaluate the effects
of the nuclear device were the primary activities engaging military
personnel.

FACT SHEET

Defense Nuclear Agency
Public Affairs Office
Washington, D C. 20305

Subject: Project TRINITY

Project TRINITY, conducted by the Manhattan Engineer District (MED),
was designed to test and assess the effects of a nuclear weapon. The
TRINITY nuclear device was detonated on a 100-foot tower on the
Alamogordo Bombing Range in south-central New Mexico at 0530 hours on
16 July 1945. The nuclear yield of the detonation was equivalent to
the energy released by detonating 19 kilotons of TNT. At shot-time,
the temperature was 21.8 degrees Celsius, and surface air pressure was
850 millibars. The winds were nearly calm at the surface; at 10,300
feet above mean sea level, they were from the southwest at 10 knots.
The winds blew the cloud resulting from the detonation to the
northeast. From 16 July 1945 through 1946, about 1,000 military and
civilian personnel took part in Project TRINITY or visited the test
site. The location of the test site and its major installations are
shown in the accompanying figures.

Military and Scientific Activities

All participants in Project TRINITY, both military and civilian, were
under the authority of the MED. No military exercises were conducted.
The Los Alamos Scientific Laboratory (LASL), which was staffed and
administered by the University of California (under contract to the
MED), conducted diagnostic experiments. Civilian and military
scientists and technicians, with assistance from other military
personnel, placed gauges, detectors, and other instruments around
ground zero before the detonation. Four offsite monitoring posts were
established in the towns of Nogal, Roswell, Socorro, and Fort Sumner,
New Mexico. An evacuation detachment consisting of 144 to 160
enlisted men and officers was established in case protective measures
or evacuation of civilians living offsite became necessary. At least
94 of these personnel were from the Provisional Detachment Number 1,