Representative background-subtracted neutron TOF spectra of ⁵⁶Fe(n, n_k) typical of Van de Graaff laboratories; these data are published in reference [37]. Peaks are labeled with the residual nucleus spin. The red line is an example of the energy-dependent neutron detector efficiency, here displayed as a function of channel number. These spectra illustrate the difficulties encountered in TOF measurements, where typically only scattering from a few low-lying states can be resolved. Clumps of levels (A-D) develop at higher energies and although one knows the levels in each clump from nuclear structure investigations, it is generally not possible to extract the individual contributions. For low mass targets, say A <  40, multiple scattering in the sample creates left-side, lower energy tails and features that make it difficult to extract the yields of neighboring peaks.