Koopmans, M.; Hwang, J.-G.; Jankowiak, A.; Ries, M.; Schiwietz, G.: Bunch-Resolved 2D Diagnostics - Streaking Combined with Interferometry. In: Changbum Kim ... [Ed.] : IBIC 2021 : Proceedings of the 10th International Beam Instrumentation Conference, Pohang, Korea, 13–17 September 2021Geneve: JACoW, 2021. - ISBN 978-3-95450-230-1, p. WEOA04/1-5
https://accelconf.web.cern.ch/ibic2021/papers/weoa04.pdf
Open Accesn Version
Abstract:
Due to the complexity of the filling pattern in the BESSY II electron-storage ring, bunch-resolved diagnostics are required for machine commissioning and to ensure the long-term quality and stability of operation. In addition, low-alpha operation and a possible VSR upgrade demand bunch-length measurements with picosecond resolution. Therefore, a dedicated beamline equipped with a fast streak camera was set up and successfully commissioned. Couplings between time- and space-coordinates also call for bunch-selective and correlated multi-parameter detection methods. Thus, the beamline and the streak camera have been made capable of direct beam-profile imaging and interferometry of the vertical beam size using the X-ray blocker baffle method *,**. The horizontal or vertical dimension can additionally be imaged with the streak camera and bunch-resolved 2D measurements are possible. Imaging the vertical direction, the characteristic dip in the center the interference pattern from pi-polarized synchrotron radiation can be observed and is used to extract bunch resolved information about the vertical beam size. The streak camera measurements are validated with direct imaging measurements from a regular CCD camera at the beamline and compared to model calculations. The results are converted into absolute values by a calibration with the BESSY II pinhole monitors.