In contrast to BRIX, SPECTRE scatters an intense laser pulse off a relativistic, laser-driven electron beam. When ultimately driven by the high-repetition-rate PFS-pro laser SPECTRE is expected to generate hard-Xray beams with similar average brilliance to BRIX (1010-1011ph/sec/mm2/mrad2/0.1%BW) but at higher photon energies between 50 and 200 keV.
Hence, it will ideally complement BRIX for research into medical imaging and therapy (see C.3). By appropriately shaping the scattering laser pulse, detrimental effects on the X-ray bandwidth arising from its temporally varying intensity can be corrected. This allows the efficient generation of X-ray pulses with a spectrum narrow enough (approx. 5%) for phase-contrast imaging. Before PFS-pro is commissioned at the end of 2015, preparatory experiments will use ATLAS-300 at a 5-Hz repetition rate whose higher electron energies will yield photons in the few-hundred keVrange.
Its beam will be split into two independent pulses and focused in a colliding geometry onto a gas target. Ensuring the perfect overlap of the two beams with the necessary precision in space and time requires an automated beam pointing and delay system. The test setup will allow the development of X-ray diagnostics. With the mean flux available from the PFS-pro-driven system first proof-of-principle experiments towards human diagnostics are possible, as outlined in the C.1 and C.2 goals.