Gregory Markari (Markarovich) Garibian (December 13, 1924 – June 8, 1991) was a Soviet Armenian physicist, academician-secretary of the Department of Physics and Mathematics of the Armenian Academy of Sciences (AS) (1973–1991). He is known for developing the Theory of Transition Radiation and showing the feasibility of functional transition radiation detectors (TRDs). [8] [9]