Cell-related effects in the pulsed optically pumped frequency standard

In this paper we describe two phenomena that may affect the medium-long term stability performance of the pulsed vapor cell Rb clock we implemented at INRIM. The first effect is an anomalously large temperature sensitivity of the clock frequency. This effect is related to the presence of large stems in the cell and the order of magnitude of the observed phenomenon may be explained in terms of a model based on the ideal gas law. The second phenomenon is related to losses in the microwave cavity induced by the presence of the dielectric material (the cell) in the cavity and by the deposition of metallic Rb on the inner walls of the clock cell.