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High intensity profile monitor for time resolved spectrometry at the CLIC Test Facility 3
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
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2012 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, Vol. 683, 29-39 p.Article in journal (Refereed) Published
Abstract [en]

The power source of the Compact Linear Collider (CLIC) relies on the generation and deceleration of a high-intensity electron drive beam. In order to provide the best radio-frequency (RF) to beam-energy transfer efficiency, the electron beam is accelerated using fully loaded RF cavities, which leads to strong beam loading effects resulting in a high-energy transient. The stability of the RF power produced by the drive beam depends on the stability of the drive beam energy and energy spread along the pulse. The control and the monitoring of the time evolution of the beam energy distribution are therefore crucial for the accelerator performance. For this purpose segmented beam dumps, which are simple and robust devices, have been designed and installed at the CLIC Test Facility 3 (CTF3). These devices are located at the end of spectrometer lines and provide horizontal beam profiles with a time resolution better than 10 ns. The segmented dumps are composed of parallel, vertical, metallic plates, and are based on the same principle as a Faraday cup: the impinging beam current is read by a fast acquisition channel. Both FLUKA and Geant4 simulations were performed to define the optimum detector geometry for beam energies ranging from 5 MeV to 150 MeV. This paper presents a detailed description of the different steps of the design: the optimization of the detector spatial resolution, the minimization of the thermal load and the long-term damage resulting from high radiation doses. Four segmented dumps are currently used in the CTF3 complex. Their measured performance and limitations are presented in this paper. Typical beam spectra as measured in the CTF3 linac are also presented along with a description of the RF manipulations needed for tuning the beam energy spectrum.

Place, publisher, year, edition, pages
2012. Vol. 683, 29-39 p.
Keyword [en]
Electron linac, Spectrometer, Segmented beam dump, CLIC Test Facility, Beam instrumentation
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-178997DOI: 10.1016/j.nima.2012.04.065ISI: 000306249000005OAI: oai:DiVA.org:uu-178997DiVA: diva2:543269

Correction in: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol. 729, p. 963, doi: 10.1016/j.nima.2013.09.005

Available from: 2012-08-07 Created: 2012-08-06 Last updated: 2013-11-21Bibliographically approved
In thesis
1. Emittance and Energy Diagnostics for Electron Beams with Large Momentum Spread
Open this publication in new window or tab >>Emittance and Energy Diagnostics for Electron Beams with Large Momentum Spread
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Following the discovery of the Higgs-like boson at the Large Hadron Collider, there is demand for precision measurements on recent findings. The Compact Linear Collider, CLIC, is a candidate for a future linear electron-positron collider for such precision measurements. In CLIC, the beams will be brought to collisions in the multi-TeV regime through high gradient acceleration with high frequency RF power. A high intensity electron beam, the so-called drive beam, will serve as the power source for the main beam, as the drive beam is decelerated in special structures, from which power is extracted and transfered to the main beam. When the drive beam is decelerated the beam quality deteriorates and the momentum spread increases, which makes the beam transport challenging. Dedicated diagnostics to monitor the momentum profile along each bunch train and transverse profile diagnostics will be needed to guarantee the reliability of the decelerator and consequently the power source of the main beam acceleration.

A test facility, CTF3, has been constructed at CERN to validate key technical aspects of the CLIC concept. The beam quality in the decelerator will be investigated in the test beam line, TBL, where several power extraction structures reduce the drive beam energy by up to 55%. At the same time, the single-bunch rms energy spread grows from the initial value of 1% to almost 6%. To monitor the parameters of such a beam is challenging but crucial for the optimization of the beamline. In this thesis we report on progress made on adapting generally used methods for beam profile measurements to the demanding conditions of a wide momentum profile. Two detector technologies are used for measuring transverse profile and momentum profile and we discuss the performance of these instruments, in the view of the large momentum spread and with the outlook towards equivalent beam profile monitors in the CLIC decelerator.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 79 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1036
beam instrumentation, particle beam diagnostic, emittance, particle collider, particle accelerator
National Category
Subatomic Physics
Research subject
High Energy Physics
urn:nbn:se:uu:diva-198080 (URN)978-91-554-8646-4 (ISBN)
Public defence
2013-05-24, Sal 2001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
EU, FP7, Seventh Framework Programme, PITN-GA-2008-215080-DITANET
Available from: 2013-05-03 Created: 2013-04-08 Last updated: 2013-08-30

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Olvegård, Maja
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