We present a new experiment which is able to monitor mass-selected cluster depositions in red time using specular reflected thermal helium scattering. Ag/sub 7//sup +/ with an incident energy of 2.86 and of 13.6 eV/atom is deposited on Pd(100) at different surface temperatures. The measurement technique relies on the large atomic cross sections Sigma of adsorbates for diffuse helium scattering. An analysis of Sigma shows that heptamers become fragmented upon impact for both energies and that some of the cluster atoms are implanted into the surface layer.