The dynamic structure factor $S(mathbf{q}, e??”)$ of a harmonically trapped Bose gas has been calculated well above the Bosea€“Einstein condensation temperature by treating the gas cloud as a canonical ensemble of non-interacting classical particles. The static structure factor is found to vanish $varpropto q^{2}$ in the long-wavelength limit. We also incorporate a relaxation mechanism phenomenologically by including a stochastic friction force to study $S(mathbf{q}, e??”).$ A significant temperature dependence of the density fluctuation spectra is found. The Debyea€“Waller factor has been calculated for the trapped thermal cloud as a function of q and the number $mathcal{N}$ of atoms. A substantial difference is found for small- and large-$mathcal{N}$ clouds.
展开▼
