Diffracted transition radiation as a new diagnostic tool for relativistic electron beam emittance

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2021-04, Vol.996, p.165132, Article 165132
• Main Authors: Goponov, Yu.A., Shatokhin, R.A., Sumitani, K., Takabayashi, Y., Vnukov, I.E.
• Format: Article
• Language: English
• Subjects: Beam diagnostics; Beam size; Crystal; Diffracted transition radiation; Parametric X-ray radiation
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2021.165132

The possibility of determining the emittance of a beam of relativistic electrons by measuring two-dimensional angular distributions of diffracted transition radiation of relativistic electrons for two distances between the crystal where the radiation is generated and the coordinate detector is considered. It is shown that the technique enables the determination of the transverse dimensions and, in the case of a mismatch between the symmetry planes of the beam and the horizontal and vertical planes, their rotation angle. A technique is proposed for determining the beam divergence by comparing the measured angular distribution of the diffracted transition radiation with a model. The sought values of the divergence are determined from the results of “fitting”, where the fitted function is the distribution for a larger distance, and the fitting function is the convolution of a model angular distribution with a two-dimensional Gaussian distribution describing the diverging electron beam. The conditions and boundaries of its practical implementation for measuring the emittance of the beam of planned electron–positron colliders at the intermediate stage of acceleration are analyzed.