Figure 1

General views of QGS setups using TDI and time-space diagram of the gamma ray paths. Schematic general view of QGS setup using TDI and time-space diagram of the SR and gamma ray paths indicated by solid arrows in the setup. The paths of the gamma rays, which arrive at the detector with time delay t after the prompt SR, are shown as examples. Nuclear excitation occurs at the filled circle points, while de-excitation occurs at the empty circle points. The Thomson scattering process of the sample occurs at the star points. The dashed arrow indicates an example of the gamma ray path when unfavourable radiation coupling occurs.