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@unpublished{podobedov:napac2019-wexba1,
author = {B. Podobedov},
title = {{Beam Dynamics Measurements with New Generation BPMs}},
booktitle = {Proc. NAPAC'19},
language = {english},
intype = {presented at the},
series = {North American Particle Accelerator Conference},
number = {4},
venue = {Lansing, MI, USA},
publisher = {JACoW Publishing, Geneva, Switzerland},
month = {oct},
year = {2019},
note = {presented at NAPAC2019 in Lansing, MI, USA, unpublished},
abstract = {Due to state-of-the-art NSLS-II beam position monitors, combined with advanced signal-processing techniques, we are now able to measure the difference between the betatron tunes of two (or more) bunches stored in the ring with the accuracy better than 10⁻⁶. For bunches of unequal charge this allows us to precisely determine the transverse kick factors. By applying local bumps, or, for in-vacuum undulators (IVUs), by varying the gap, we can also precisely measure the impedance of individual ring components. Since the tunes of unequally charged bunches are measured simultaneously, this reference method is virtually immune to machine drifts, as well as other systematic errors. For instance, in our IVU measurements vs. undulator gap, we can accurately determine current-dependent tuneshifts two orders of magnitude smaller than the tuneshift induced by the natural focusing of the undulator. Other examples of measurements performed with similar, or related, techniques include single-shot measurements of tune-shift with amplitude as well as non-invasive lattice characterization during user operations.},
}