NEVADA TEST SITE

An experimental device designed by Los Alamos Scientific Laboratory, code named Fizeau was detonated at 9:45 a.m. today atop a 500-foot tower in Yucca Flat.

There were approximately 25 experiments on the sequence timer. Biomedical studies begun on the Franklin shot and continued on other shots were concluded on Fizeau. Twenty-five aircraft participated in technical and support operations.

The shot was viewed from on-site by Civil Defense and news media observers and by eight members of ranch families from the area northeast of the Test Site.

The cloud rose very rapidly until its top was above 45,000 feet, with observers having the opinion that not much of the debris from the stem was drawn up into the top. It was sheared quickly by the winds into three major segments. The cloud top was being blown at 13 knots west of due north; the middle section was moving at 13 knots east of due north; the lower section was moving at lesser speed northwest. Because of the shear and the low wind speeds, only relatively light fallout is anticipated at the distance of occupied places, with the heavier fallout on the Test Site and adjacent portions of the gunnery range.

The detonation was felt by observers as a sharp blow, and was heard as three quite loud sharp cracks followed by prolonged hill echoes and rumblings. It approximated 16 millibars of pressure at the Control Point. It was heard at Bishop and Inyokern as rumbles and bangs.