Investigation of Coherent Diffraction Radiation from a dual target system at CTF3 and its application for longitudinal bunch profile diagnostics

Abstract

A coherent Diffraction Radiation (CDR) originating from a dual-target system was investigated theoretically and experimentally. Diffraction Radiation is emitted when a bunch of charged particles moves in the vicinity of an optical obstacle. The coherency of the effect is achieved when electrons in the bunch radiate in phase, i.e. the wavelength of the radiation is comparable to or larger than the bunch length. An experimental setup at the CLIC Test Facility 3 (CTF3) at CERN was modified by installation of a second target. In the experiment two targets are positioned to one side of the beam and the radiation originating from them is translated towards a Michelson interferometer. The ultimate goal of the experiment is to reconstruct the longitudinal parameters of the beam from the CDR spectrum. A precise knowledge of the bunch time profile is particularly important in the context of a luminosity challenge in the future linear colliders and therefore the development of a non-invasive and robust longitudinal beam diagnostic technique is very important. A theoretical model based on the classical Diffraction Radiation theory was devel- oped to calculate the spatial distributions of the CDR from the dual-target system and based on this knowledge to calculate a single electron spectrum which is used in a bunch shape reconstruction. The Kramers-Kronig analysis as a tool for the bunch profile reconstruction was studied theoretically. The CDR spatial distributions were measured at the experimental setup and compared with the theory. The ability of the two-target system to cut-off the backgrounds originating upstream of the experimental setup was tested.EThOS - Electronic Theses Online ServiceGBUnited Kingdo