Figure 4.

(a) Heatmap of reconstructed dispersion $S(\mathbf{q},\omega )$ of ${}^3\text{He}$ at $T=1.2\text{K}$. Good agreement is found with the experimental data from Ref.²⁴ (blue circles). Because of the higher mass, the roton minimum is shifted to higher q for ${}^4\text{He}$ as the theoretical results from Ref.²² show (black diamonds). (b, c) Dynamic structure factor $S(\mathbf{q},\omega )$ for $q=1.62$ Å⁻¹ and $q=2.01$ Å⁻¹, solid purple: reconstructed PIMC data; yellow triangles: experimental data by Sköld et al.²⁴.