Figure 12: Relative signal amplitudes for -rays and neutrons for two hybrid type experiments. On the left is shown the primary to secondary scintillation signal amplitudes for a two-phase xenon instrument [35]. Neutrons have large S1/S2 ratios. The right hand panel shows the ionisation versus phonon performance of the CDMS germanium bolometer [3]. -rays populate the plot above the solid line with nuclear recoils below it. The circled points are experimental data thought to originate from neutron recoils.