Figure 1. Layout of the self-synchronized All-optical Compton Scattering Experimental setup.

The 0.8-um-wavelength, 33fs-duration pulses from the 200 TW Ti:sappire laser system were focused onto the two-segment (0.8 + 3 mm) pure helium gas jets onto the supersonic nozzles. About 5% of the pump laser was split off as a probe pulse, which crossed the interaction region perpendicularly into a 4f Michelson-type interferometer system, to measure the plasma density profile and monitor the laser evolution. The produced e-beams were deflected by a 90-cm-long dipole electromagnet with a maximum magnetic field of 1.1 Tesla, and measured by a Lanex phosphor screen (PS) imaged onto an intensified charge-couple device 16-bit (ICCD) in a single shot. A 30-um-thick Al foil or 20-um-thick Ti as a plasma mirror was presented to reflect the driving laser to scatter the generated e-beams to produce γ-rays. A 10-cm-thick wolfram collimator with a 2-mm hole was placed to block the irrelevant radiation. The lead-grid filter and Lu₂SiO₄(LSO)-crystal scintillator with a diameter of 50 mm were placed 5.2 m downstream, imaged with a CCD camera encased by the lead baffles for detecting γ-rays.