Ionization phase retrieval by angular streaking from random shots of XUV radiation

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We demonstrate an accurate phase retrieval of extreme ultraviolet (XUV) atomic ionization by streaking the photoelectron in a circularly polarized infrared (IR) laser field. Our demonstration is based on a numerical solution of the time-dependent Schrodinger equation. We test this technique using the hydrogen atom ionized by isolated attosecond XUV pulses across a wide range of the photon energies. Importantly, the proposed method works in a random shot mode when the time delay between the ionizing and streaking XUV and IR pulses may vary from shot to shot. This is a significant advantage over the existing interferometric techniques which require a systematic and controllable scan of the XUV and IR delay in one set of measurements. Such a scan may not be possible to take because of the arrival time jitter inherent to the stochastic nature of self-amplified free-electron laser radiation.