A mass spectrometer used for separating the isotopes and of uranium. Its name is a concatenation of Cal. U.-tron, since it was invented at the University of California.
References
Heilbron, J. L. and Seidel, R. W. "Episode 2: The Calutron." in Lawrence and His Laboratory: A History of the Lawrence Berkeley Laboratory. Berkeley, CA: University of California Press, 1990. http://www.lbl.gov/Science-Articles/Research-Review/Magazine/1981/81fepi2.html.
