High accuracy evaluation of CENAM's primary frequency standard: second order Doppler shift

The Centro Nacional de Metrologia in Mexico has developed an optically pumped cesium beam frequency standard, the CsOP-1. Currently, the major sources of systematic effects are being analysed and their corresponding frequency shift effects in the CsOp-1. In this work, we re-evaluate the second order Doppler shift by taking into account the modulation parameter.