Fig. 7

2D histogram of peak height of 990 nm PSLs arriving at ICD-QD2, plotted against QD potential. ICD-QD2 is not directly calibrated, but the calibration factor can be inferred by reference to another detector (ICD2) . The average number of charges on a 990 nm PSL as measured by ICD2 for particles selected with the QD set to 400 V is 17000. This corresponds to a peak height of 0.45 V on ICD-QD2, so the Rayleigh limit of 26500 charges would correspond to about 0.7 V (as shown by the dashed red line). The large number of peaks with heights of <0.2 V are due to particles that have hit the detector pickup instead of passing all the way through