TY  - JOUR
AU  - Trebushinin, Andrei
AU  - Serkez, Svitozar
AU  - Freund, Wolfgang
AU  - Perosa, Giovanni
AU  - Koch, Andreas
AU  - Gruenert, Jan
AU  - Geloni, Gianluca
AU  - Qin, Weilun
AU  - Tomin, Sergey
TI  - Noninterferometric method for transverse electron beam size diagnostic with synchrotron radiation at a free-electron laser
JO  - Physical review accelerators and beams
VL  - 28
IS  - 11
SN  - 2469-9888
CY  - College Park, MD
PB  - American Physical Society
M1  - PUBDB-2025-05674
SP  - 112801
PY  - 2025
AB  - We present a noninterferometric method for measuring the transverse electron beam size at the European XFEL based on synchrotron radiation intensity autocorrelation. The technique enables cell-by-cell diagnostics along the SASE1 undulator using existing hardware: a commissioning monochromator and a spatial x-ray detector. We extend the results of [A. Trebushinin et al., companion paper, First observation of synchrotron radiation spikes for transverse electron beam size measurements at a free-electron laser, Phys. Rev. Lett. 135, 215001 (2025).] focusing on data analysis procedures and technical implementation. Our method allows for extraction of the beam size from noisy measured intensity distributions with a signal-to-noise ratio as low as 0.9 and is capable of distinguishing between the projected and slice sizes. To validate our approach, we introduced a mismatch in the magnetic lattice, inducing a controlled sinusoidal variation in the beam size along the undulator. The corresponding modulation was clearly reproduced in the electron beam size values extracted from the autocorrelation measurements. This method offers a practical solution for transverse electron beam size diagnostics in high-energy linacs, with direct application to the operation and tuning of free-electron laser facilities.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1103/31gl-qyk7
UR  - https://bib-pubdb1.desy.de/record/642868
ER  -