Fig. 9. Comparison of the measured ³He scattering from Cu(111) signals (black solid line) with the calculated signals (red dashed line) for B₁ scans when B₂ = 11.2 gauss metre at a nozzle temperature of 40 K (top row), B₁ scans when B₂ = −11.2 gauss metre at a nozzle temperature of 60 K (second row), B₂ scans when B₁ = −11.2 gauss metre at a nozzle temperature of 40 K (third row) and B₂ scans when B₁ = 11.2 gauss metre at a nozzle temperature of 60 K (bottom row). Each column magnifies a different echo, with the first and third showing either the parallel echo (B₁ = B₂, the largest amplitude) or anti-parallel echo (B₁ = −B₂, the smallest amplitude), and the middle column showing the X′ echo in the B₁ scans (top two rows) or X echo in the B₂ scans (bottom two rows).