Optical pumping of a caesium beam and detection of the 0-0 'clock' transition

The time evolution for the populations of the ground state hyperfine Zeeman levels of caesium atoms are analysed for the case where a caesium beam is optically pumped, under different conditions of polarisation, either with a weak monochromatic laser light or with the resonance light from a spectral lamp filtered by a caesium cell. The optical detection of the 0-0 'clock' transition in the atomic beam is also discussed for applications to frequency standards.