material was accomplished by joint teams of Los Alamos Scientific Laboratory and military personnel, who searched the most probable fallout areas with radiation-detection instruments, questioned residents, and took soil samples for laboratory analyses and comparison with original radiation-monitor readings.

Residents of the village of Bingham, New Mexico, some 18 miles from ground zero, were startled by a brilliant flash of light that awakened them and their families, as recounted to monitoring teams in interviews a few hours after the detonation (Hoffman, 1947). Those interviews were the first of civilians who had witnessed an atomic-bomb explosion. A previous story had been arranged regarding an explosion of store ammunition at the Alamogordo bombing range to answer questions for national security purposes.

The first test was followed by the detonation over Hiroshima, Japan, on August 6, 1945, of the bomb named LITTLE BOY because it was small (10 ft long, 28 in. in diameter, and weighing 9,000 lb) compared with FAT MAN (12 ft long, 60 in. in diameter, weighing 10,800 lb, and having fins), which was detonated over Nagasaki, Japan, on August 9, 1945, and resulted in ending the war with Japan. Unlike TRINITY, LITTLE BOY was a gun-type device containing uranium-235 (235U) and had not been previously tested; FAT MAN was identical with TRINITY except for added tail fins and associated hardware to convert it from a test device to a weapon.

The end of World War II was followed by two nuclear tests at Bikini Atoll in the Pacific Ocean during Operation CROSSROADS, in July 1946. The devices detonated, Shots ABLE and BAKER, each had a yield of 21 kilotons; they were essentially the same as the device detonated at Shot TRINITY and the bomb dropped over Nagasaki. The mostly military participants in CROSSROADS numbered about 43,000.

Operations SANDSTONE in 1948, GREENHOUSE in 1951, IVY in 1952, and CASTLE in 1954—all in the Pacific—were interspersed with Operations RANGER in January-February 1951, BUSTER-JANGLE in October-November 1951, TUMBLER-SNAPPER in 1952, and UPSHOT-KNOTHOLE in 1953 at what came to be called the Nevada Test Site (NTS) (it was called the Nevada Proving Ground, or NPG, until December 1954). Test yields at the Pacific tests increased to 15.3 megatons (MT) of TNT for CASTLE BRAVO in 1954, and yields at NTS tests increased to 74 kilotons with Shot HOOD during Operation PLUMBBOB in 1957, which was the highest atmospheric yield on the continent.

Additional atmospheric test series in the Pacific were WIGWAM in 1955, HARDTACK Phase I in 1958, and DOMINIC Phase I in 1962. Additional atmospheric test series in Nevada were TEAPOT in 1955, HARDTACK Phase II in 1958, and DOMINIC Phase II in 1962. Another test operation was ARGUS, consisting of three nuclear detonations on rockets, each 1-2 kilotons in yield, hundreds of miles above the Atlantic Ocean—far enough above the ocean surface that no detectable exposures of test participants occurred. Overall, the United



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