Characterisation of a magneto-optical trap for CaF molecules

We present a detailed characterization of a magneto-optical trap (MOT) of CaF molecules. We capture approximately $2.2\times10^4$ molecules in the MOT from a buffer gas molecular beam which is slowed via radiation pressure. At the highest laser intensity, the lifetime of the molecules in the MOT is about 100ms, the trap frequency is 94Hz and the damping coefficient is 390(4)s$^{-1}$. The molecules reach an equilibrium temperature of 12mK which is nearly 50 times higher than the Doppler limit. We explore how the scattering rate, trap frequency, damping coefficient and temperature depend on the intensity. We compare our results to standard Doppler cooling theory and to an advanced model that takes into account the effect of polarization gradients.