Speaker
Mr
Konstantin Lekomtsev
(Royal Holloway College-University of London)
Description
For the Compact Linear Collider (CLIC) the demonstration of a bunch train compression and combination in the recombination rings is crucially important. The performance of the CLIC Test Facility 3 (CTF3), at the moment, and CLIC, in the future, depends on the control and monitoring of the electron bunch length.
Diffraction Radiation (DR) has been experimentally investigated as a tool for beam diagnostics over the course of the last 15 years and proved to be effective, non-intercepting tool for longitudinal beam diagnostics purposes. Online bunch length monitoring, based on detection of a coherent radiation spectrum, is a promising technique, providing the single electron spectrum is predictable. However, an idealised theory along with coherent backgrounds generated by the beam complicate the result interpretation.
The experimental setup for longitudinal bunch profile measurements, based on the Coherent Diffraction Radiation (CDR), is installed at CTF3. Two silicon wafers are positioned on one side of the beam and the radiation, originated from them, is translated towards a Michelson Interferometer. The first target cuts off the background generated by the beam from upstream. Over the last two years the experimental setup has undergone several modifications: the second target was installed upstream of the first one; a new silicon beam splitter was installed; several detectors were tested for the potential use in the interferometer.
A theoretical model, based on the Classical Diffraction Radiation theory, was developed for the two target configuration of the experimental setup [1]. The model includes: calculation of the DR from the targets for different polarisation components of the radiation; comparison of the DR spatial distributions for the single target configuration and the dual target configuration; and, also, calculation of a single electron spectrum, which is utilized for the longitudinal beam profile reconstruction.
In this report the recent hardware modifications will be shown. The spectral measurements, performed for the two target configuration, using the ultra fast Schottky Barrier Diodes will be reported. The investigation of the CTF3 bunch length variation issues will be discussed. The measurements of the horizontal and the vertical polarisation components of the radiation spatial distribution, measured using the detectors sensitive over different frequency ranges, will be presented and compared with the theory. The measurements performed in combination with the streak camera will be shown as well.
[1] K. Lekomtsev, G. Blair, G. Boorman, R. Corsini, P. Karataev, T. Lefevre and M. Micheler, Coherent Diffraction Radiation experiment at CTF3 – simulation studies, IL NUOVO CIMENTO Vol. 34C, N.4, 2010 (available online).
Author
Mr
Konstantin Lekomtsev
(Royal Holloway College-University of London)
Co-authors
Mr
Gary Boorman
(Royal Holloway College-University of London)
Prof.
Grahame Blair
(Royal Holloway College-University of London)
Dr
Pavel Karataev
(Royal Holloway College-University of London)
Dr
Roberto Corsini
(CERN)
Dr
Thibaut Lefevre
(CERN)
