A mass spectrometer that produces a graphical representation of the mass spectrum WordNet 3.0 & Open English WordNet

A mass spectrometer. Wiktionary

An analytical technique that measures the mass / charge ratio of the ions formed when a molecule or atom is ionized, vaporized and introduced into a vacuum. Mass spectrometry may also involve breaking molecules into fragments - thus enabling its structure to be determined. Wiktionary

Analytical tecnique. Wiktionary (translation)