Standardization of 14C by liquid-scintillation coincidence counting

Abstract 14 C in the form n[1− 14 C]-hexadecane in toluene has been standardized by means of liquid-scintillation coincidence counting, using matched phototubes. Both integral pulse-amplitude discrimination with extrapolation to zero pulse amplitude, and integral incident-photon discrimination of ( N ′ N ″) N c as a function of reciprocal phototube output current were made to give the disintegration rate as the reciprocal anode current approaches zero.