Shot DIXIE, Operation Upshot-Knothole, April 1953. The cloud near the dancer's foot is a stemless mushroom cloud. There are a number of "Miss Atomic Bomb" photos floating around, but they were all, as far as I know, not official US government activities. This one, on the other hand, is different. For one thing, it's a US government photo, probably taken on the premises of the Nevada Test Site, by someone who knew exactly when and where this particular test was going to be set off. Knowing nothing about dance, I consulted a good friend of mine, Dawn Davis Loring, who knows about such things, and she told me that judging from the appearance and posture of the person here, she was possibly a showgirl (the technical ability is competent but not expert). Anyway, I've really no idea why they took this photo, and the archives apparently have no more information on it.
U.S. Department of Energy/National Nuclear Security Administration, Nevada Site Office, UK-53-093.