Figure 4: Experimental set-up.

Schematic of the set-up consisting of a single-shot Stereo-ATI phase meter (left chamber) and a REMI spectrometer (right chamber). A beamsplitter (BS) directs the laser pulses into both chambers. Each arm is equipped with a pair of fused-silica wedges for compensating residual chirp. The phase meter contains a layer of μ-metal to shield from external magnetic fields. The inner gas cell is filled with xenon gas at a pressure of about 5×10⁻³ mbar. In the Stereo-ATI, xenon atoms are ionized near the focus of the horizontally polarized laser beam, and the electrons produced enter the high-vacuum drift tubes through slits. Electrons resulting from the ionization by a single-laser shot are detected by MCP detectors to the left and to the right, enabling the determination of the CEP for each REMI event, as described in the text. Simultaneously, ions and electrons created in the overlap of the laser focus and a skimmed supersonic jet of the REMI are extracted from the interaction region by a weak electric field (3 V cm⁻¹) and detected by MCP and delay line detectors on the left and right side of the instrument, respectively. Helmholtz coils are used to facilitate the detection of electrons over a solid angle of 4π. The jet is efficiently pumped by the catcher. The master trigger for the electronics is provided by a fast photodiode (PD). The ion and electron optics are symmetric in reality, and a few electrodes have been removed for visualization of the laser path.