1. A mass spectrometer, an electromagnetic apparatus for separating isotopes of uranium according to mass.

Its name is a combination of California University + tron (Cal+U+tron) in tribute to the University of California, Ernest O. Lawrence's institution and the contractor of the Los Alamos laboratory. It was developed during the Manhattan Project and was similar to the cyclotron invented by Lawrence.

2. A device that separates isotopes by ionizing the sample, accellerating the ions in a strong electric field, and then passing them through a strong magnetic field.