Mattauch–Herzog geometry
An arrangement for a double-focusing mass spectrograph in which a deflection of π 4 2 radians in a radial electrostatic field is followed by a magnetic deflection of π 2 radians.
PAC, 1991, 63, 1541. 'Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)' on page 1546 (