missing mass spectrometer

missing mass spectrometer

[‚mis·iŋ ¦mas spek′träm·əd·ər]
(particle physics)
An apparatus which measures the momentum of the recoil protons in a reaction such as π-+ pp + (MM)-, in order to determine the distribution of masses of the MM system, without any detailed observations on this system.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.