12:00–1:00 pm
Please join us:
Ihar Lobach’s PhD Thesis Defense
Wednesday September 8th at 12:00PM CDT
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STATISTICAL PROPERTIES OF UNDULATOR RADIATION. CLASSICAL AND QUANTUM EFFECTS.
This talk presents an experimental study into the statistical properties of synchrotron radiation in the IOTA storage ring at Fermilab. For every revolution in the ring, we recorded the number of detected photons produced by the electrons when they pass in an undulator—a series of magnets with alternating polarities installed in one section of the ring. The recorded numbers are different from turn to turn. In the extreme case of a single electron circulating in the ring, we detected zero photons during most revolutions, sometimes one, and sometimes more than one. Clearly, this behavior is due to the quantum nature of light and the number of detected photons should follow the Poisson distribution. If we gradually increase the number of electrons in the ring, the Poisson fluctuations (rms) decrease proportionally to the reciprocal of the square root of the number of electrons. However, at some point, another fluctuation mechanism becomes dominant—the interference of fields radiated by different electrons. Random changes in the relative electron positions and velocities inside the electron bunch result in fluctuations in the total emitted energy per pass in the undulator. We observed this type of fluctuations in our experiments with 1–3 billion electrons in the ring. The magnitude of these fluctuations depends on the size, shape, and angular divergence of the electron bunch. Therefore, this effect can be used for noninvasive electron beam diagnostics. This technique may be particularly beneficial for the existing and next-generation low-emittance high-brightness ultraviolet and x-ray synchrotron light sources.
Committee members:
Sergei Nagaitsev (Chair)
Giulio Stancari
Kwang-Je Kim
Linda Young
Ihar will be a postdoc at the Advanced Photon Source (APS) at Argonne National Laboratory.