S. Nagaitsev, A.L. Romanov, A.V. Shemyakin, G. Stancari
Fermilab, Batavia, Illinois, USA
Funding:The work is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Two experiments were carried out to study the statistical properties of undulator radiation in the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab. The first experiment studied the turn-to-turn fluctuations in the power of the radiation generated by an electron bunch. The magnitude of these fluctuations depends on the 6D phase-space distribution of the electron bunch. In IOTA, we demonstrated that this effect can be used to measure some electron bunch parameters, small transverse emittances in particular. In the second experiment, a single electron was stored in the ring, emitting a photon only once per several hundred turns. In this regime, any classical interference-related collective effects were eliminated, and the quantum fluctuations could be studied in detail to search for possible deviations from the expected Poissonian photon statistics. In addition, the photocount arrival times were used to track the longitudinal motion of a single electron and to compare it with simulations. This allowed us to determine several dynamical parameters of the storage ring such as the rf cavity phase jitter and the dependence of the synchrotron motion period on amplitude.
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P. Ilinski
MAX IV Laboratory, Lund University, Lund, Sweden
Funding:Research conducted at MAX IV, a Swedish national user facility, is supported by the Swedish Research council, the Swedish Governmental Agency for Innovation Systems, and Formas. A novel photoemission type of X-ray Beam Position Monitor (XBPM) for the ’white’ undulator radiation is proposed. The XBPM employs beamline frontend fixed mask as a source of photocurrent signal. Signal spatial distribution and XBPM response were analyzed for various undulator radiation parameters.
B. Keil, R. Ditter, M. Gloor, G. Marinkovic, J. Purtschert
PSI, Villigen PSI, Switzerland
We have developed a new BPM electronics platform based on a MultiProcessing System-on-Chip (MPSoC). This contribution introduces the first application of the platform at the Paul Scherrer Institute (PSI), which is the cavity BPM system for the SwissFEL soft X-ray undulator beamline called ’Athos’ [1], where a larger number of systems are now operational. Measurement results and differences to the predecessor system will also be presented.
M. Siano
Università degli Studi di Milano, Milano, Italy
D. Butti, T. Lefèvre, S. Mazzoni, G. Trad
CERN, Meyrin, Switzerland
G. Geloni
EuXFEL, Schenefeld, Germany
U. Iriso, A.A. Nosych, L. Torino
ALBA-CELLS, Cerdanyola del Vallès, Spain
B. Paroli, M.A.C. Potenza
Universita’ degli Studi di Milano & INFN, Milano, Italy
"Fast Monte-CarlO approach to Coherence of Undulator Sources" (FOCUS) is a new GPU-based code to compute the transverse coherence of X-ray radiation from undulator sources. The code relies on scaled dimensionless quantities and analytic expressions of the electric field emitted by electrons in an undulator, obtained in the frequency domain under paraxial approximation (justified by the assumption of ultra-relativistic electrons) and free space propagation, with the addition of the resonance approximation. We describe the core structure of the code, which exploits GPUs for massively parallel computations. We validate our approach by direct comparison with SRW (Synchrotron Radiation Workshop) simulations. The benchmarks prove that FOCUS yields similar results with respect to SRW, while at the same time reducing the computation times by five orders of magnitude. Finally, we show examples of applications to beam size diagnostics. The aim of the code is to fast evaluating the transverse coherence properties of undulator X-ray radiation as a function of the electron beam parameters, and to support and help preparing more rigorous numerical simulations with traditional codes like SRW.
C. Takahashi, A. Freitas, V. Hardion, M. Holz, M. Lindberg, M. Sjöström, H. Tarawneh
MAX IV Laboratory, Lund University, Lund, Sweden
Feedforward control loops are used in numerous applications to correct process variables. While feedforward control loops correct process variables according to expected behaviour of a system at any given set point, feedback loops require measurements of the output to correct deviations from the set point. At MAX IV, a generic multi-dimensional input and output feedforward controller was implemented using TANGO Control System. This paper describes the development and use cases of this controller for beam orbit and optics corrections at MAX IV.
N. Samadi, G. Lovric, C. Ozkan Loch
PSI, Villigen PSI, Switzerland
X. Shi
ANL, Lemont, Illinois, USA
The advance in low-emittance x-ray sources urges the development of novel diagnostic techniques. Existing systems either have limited resolution or rely heavily on the quality of the optical system. An x-ray beam property analyzer based on a multi-crystal diffraction geometry was recently introduced. By measuring the transmitted beam profile of a dispersive Laue crystal downstream of a double-crystal monochromator, the system can provide a high-sensitivity characterization of spatial source properties, namely, size, divergence, position, and angle in the diffraction plane of the system at a single location in a beamline. In this work, we present the experimental validation at a super-bending magnet beamline at the Swiss Light Source and refine the method to allow for time-resolved characterization of the beam. Simulations are then carried out to show that the system is feasible to characterize source properties at undulator beamlines for fourth-generation light sources.
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M. Masaki, H. Dewa, T. Fujita, H. Maesaka, K. Soutome, T. Sugimoto, S. Takano, M.T. Takeuchi, T. Watanabe
JASRI, Hyogo, Japan
T. Fukui, H. Maesaka
RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan
K. Kubota
SES, Hyogo-pref., Japan
K. Soutome, T. Sugimoto, S. Takano, H. Tanaka, T. Watanabe
RIKEN SPring-8 Center, Hyogo, Japan
We developed a new correction algorithm for closed orbit distortion (COD) based on adaptive feedforward control (AFC). The AFC system effectively works for the suppression of the fast COD due to known error sources with repetitive patterns such as helicity-switching undulators. The scheme aims to counteract error sources by feedforward correctors at the position or in the vicinity of error sources so that a potential risk of unwanted local orbit bumps, which is known to exist for the global orbit feedback, can be eliminated in a reliable and accurate manner. This option is especially advantageous when an error source causes an angular distortion of photon beams such as a fast orbit distortion near undulators. Thus, the AFC provides a complementary capability to a so-called fast global orbit feedback (FOFB) for coming next-generation light sources where ultimate light source stability is essentially demanded. In this talk, introduction to the AFC, its theoretical aspect and advantages, the system overview, the experimental results for the effects of AFC will be presented. M. Masaki, et al., J. Synchrotron Rad. 28, 1758-1768 (2021).
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