Figure 4

(a) Simulated electron bunch current profiles at the Al target for two compression factors in the linac (CF1-yellow and CF2-brown) and fixed R₅₆ in the dump line. For comparison, a case without CSR in the dump line dipole magnets is shown (cyan), see also Table 2. (b) Calculated CTR spectra. A threshold of 20 dB from the main intensity peak is indicated by the gray area. (c) Solid lines: CTR pulse energy integrated over the frequency range 0.01–10 THz and calculated from the above current profiles. Dots with error bars: measured pulse energy, see also Table 2. The pulse energy values refer to emission at the Al foil, i.e., actual measurements are reduced by ∼30% from the shown values because of the transmission efficiency of the Diamond window installed between the foil and the pyroelectric detector. Electron beam and linac parameters are in Table 1, for the beam energy E = 871 MeV at the linac end.