In this technique, “frame overlap” can spoil the measurement if a chopper is used and the energy spectrum of the source is too broad. In analogy to NMR, a variant of this technique using polarized beams is called “spin echo.” This technique controls the difference between initial and final wavevector in “constant-Q mode,” which has been implemented since the 1950s with “triple axis” configurations. Bertram (*) Brockhouse and Clifford Shull won a Nobel for this technique, which can measure bulk properties due to the beam's high penetrating power. This technique often uses a spallation source (-5[1])to generate the incident particle beam, which then undergoes elastic or inelastic collisions with the analyte. For 10 points, what technique probes a material’s structure by observing the deflection of uncharged (10[1])particles? ■END■ (10[1]0[2])