Measured LFI 70 GHz EE (top) and BB (bottom) null power spectra for ℓ = 2, 3, and 4 (vertical lines), compared to the distribution derived from noise-only Monte Carlo simulations. Null spectra from the difference between full data and specific surveys combinations: left Survey 1 and Survey 3; (middle) Survey 2 and Survey 4; and (right) Survey 5 and Survey 7. It is clear that Survey 2/Survey 4 stands out with respect to the others.