Quasimonochromatic resonant diffraction radiation as a possible tool for non-invasive beam diagnostics

The characterization of the transverse phase space for high charge density and high energy electron beams is demanding for the successful development of the next generation light sources and linear colliders. Due to its non-invasive and non-intercepting features, Optical Diffraction Radiation (ODR) is considered as one of the most promising candidates to measure the transverse beam size and angular divergence. The recent results of our experiment, based on the detection of the ODR angular distribution to measure the electron beam transverse parameters and set up at FLASH (DESY), are presented. A thin stainless steel mask has been installed at 45° with respect to the DR target and normally to the beam propagation to reduce the contribution of synchrotron radiation (SR) background. In addition, interference between the ODR emitted on the shielding mask in the forward direction and the radiation from the DR target in the backward direction is observed. This is what we call Optical Diffraction Interferometry (ODRI). The contribution of this interference effect to the ODR angular distribution pattern and, consequently, its impact on the beam transverse parameters is discussed.

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Ultra-monochromatic far-infrared Cherenkov diffraction radiation in a super-radiant regime

Scientific Reports ◽

10.1038/s41598-020-76996-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

P. Karataev ◽

K. Fedorov ◽

G. Naumenko ◽

K. Popov ◽

A. Potylitsyn ◽

...

Keyword(s):

Spectral Range ◽

Far Infrared ◽

High Energy ◽

Spectral Lines ◽

Diffraction Radiation ◽

Photon Yield ◽

Non Invasive ◽

Relative Bandwidth ◽

Advanced Tool ◽

Fast Charged Particle

AbstractNowadays, intense electromagnetic (EM) radiation in the far-infrared (FIR) spectral range is an advanced tool for scientific research in biology, chemistry, and material science because many materials leave signatures in the radiation spectrum. Narrow-band spectral lines enable researchers to investigate the matter response in greater detail. The generation of highly monochromatic variable frequency FIR radiation has therefore become a broad area of research. High energy electron beams consisting of a long train of dense bunches of particles provide a super-radiant regime and can generate intense highly monochromatic radiation due to coherent emission in the spectral range from a few GHz to potentially a few THz. We employed novel coherent Cherenkov diffraction radiation (ChDR) as a generation mechanism. This effect occurs when a fast charged particle moves in the vicinity of and parallel to a dielectric interface. Two key features of the ChDR phenomenon are its non-invasive nature and its photon yield being proportional to the length of the radiator. The bunched structure of the very long electron beam produced spectral lines that were observed to have frequencies upto 21 GHz and with a relative bandwidth of 10–4 ~ 10–5. The line bandwidth and intensity are defined by the shape and length of the bunch train. A compact linear accelerator can be utilized to control the resonant wavelength by adjusting the bunch sequence frequency.

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