Is there a twenty year wave in the diurnal anisotropy of cosmic rays?

Data obtained with the Deep River neutron monitor and the underground vertical muon telescope at Embudo for the period 1965-1979 are analyzed. The data show that for 1957-1970 the diurnal anisotropy is unidirectional. During 1971-1979, the diurnal anisotropy consists of two components. One is in the east-west direction and the other is the radial component, with direction along 12:00 LT. The latter attains a maximum amplitude in 1976. No evidence is found for the existence of the twenty year wave in the diurnal anisotropy of cosmic rays.