uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Emittance and Energy Diagnostics for Electron Beams with Large Momentum Spread
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
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.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1036
Keyword [en]
beam instrumentation, particle beam diagnostic, emittance, particle collider, particle accelerator
National Category
Subatomic Physics
Research subject
High Energy Physics
Identifiers
URN: urn:nbn:se:uu:diva-198080ISBN: 978-91-554-8646-4 (print)OAI: oai:DiVA.org:uu-198080DiVA: diva2:615189
Public defence
2013-05-24, Sal 2001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Opponent
Supervisors
Funder
EU, FP7, Seventh Framework Programme, PITN-GA-2008-215080-DITANET
Available from: 2013-05-03 Created: 2013-04-08 Last updated: 2013-08-30
List of papers
1. High intensity profile monitor for time resolved spectrometry at the CLIC Test Facility 3
Open this publication in new window or tab >>High intensity profile monitor for time resolved spectrometry at the CLIC Test Facility 3
Show others...
2012 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, 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.

Keyword
Electron linac, Spectrometer, Segmented beam dump, CLIC Test Facility, Beam instrumentation
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-178997 (URN)10.1016/j.nima.2012.04.065 (DOI)000306249000005 ()
Note

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: 2017-12-07Bibliographically approved
2. Beam profile monitoring at the test beam line at the Compact Linear Collider test facility
Open this publication in new window or tab >>Beam profile monitoring at the test beam line at the Compact Linear Collider test facility
Show others...
2013 (English)In: Physical Review Special Topics. Accelerators and Beams, ISSN 1098-4402, E-ISSN 1098-4402, Vol. 16, no 8, 082802- p.Article in journal (Refereed) Published
Abstract [en]

The Compact Linear Collider, CLIC is a study for a future linear electron-positron collider based on a two-beam acceleration scheme in which a high intensity drive beam is decelerated in order to provide the power to accelerate the main beam for collision in the TeV range. The power extracted from the drive beam deteriorates the beam quality and increases the energy spread significantly. Monitoring of the beam properties is therefore challenging but essential. These challenges are being addressed experimentally at the CLIC Test Facility where up to 55% of the power is extracted from the beam in the test beam line, TBL, a small-scale version of the CLIC drive beam decelerator, leaving the beam with a very wide energy profile. For monitoring of the transverse beam profile and Twiss parameters we use Optical Transition Radiation screens and quadrupole scans. The intra-pulse train energy spectrum before and after deceleration is measured with segmented beam dumps. In this report we discuss the performance of these diagnostic devices with a particular emphasis on the large energy spread and its effect on the beam imaging techniques, and with a final outlook to the CLIC drive beam diagnostics.

Keyword
CLIC Test Facility, electron decelerator, optical transition radiation, quadrupole scan, segmented beam dump
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-197570 (URN)10.1103/PhysRevSTAB.16.082802 (DOI)000323611000002 ()
Projects
CLIC
Available from: 2013-04-08 Created: 2013-03-27 Last updated: 2017-12-06Bibliographically approved
3. Effect of large momentum spread on emittance measurements
Open this publication in new window or tab >>Effect of large momentum spread on emittance measurements
2013 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 707, 114-119 p.Article in journal (Refereed) Published
Abstract [en]

We discuss the systematic errors in emittance measurements with quadrupole scans and four screens due to large momentum spread in the beam. This is particularly relevant in the drive beam complex of CLIC and the test beam line TBL in the CTF3 facility at CERN. We also discuss methods to adapt the model to correct for the systematic errors.

Keyword
Beam diagnostic, Chromatic effects, Quadrupole scans
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-197037 (URN)10.1016/j.nima.2012.12.114 (DOI)000314956100016 ()
Available from: 2013-03-19 Created: 2013-03-18 Last updated: 2017-12-06Bibliographically approved
4. Conceptual design of the post-PETS instrumentation line for CLIC
Open this publication in new window or tab >>Conceptual design of the post-PETS instrumentation line for CLIC
2013 (English)Manuscript (preprint) (Other academic)
Abstract [en]

We propose a method to measure the time-resolved momentum distribution and beam size at the end of the decelerator in the drive beam complex of the Compact Linear Collider, CLIC. Conventional diagnostic methods are hampered by the very high beam power and large energy spread of the drive beam after up to 90% of its kinetic energy is converted into microwave power. Our method is based on sweeping the beam in a circular pattern to determine the momentum distribution and recording the beam size on a screen using optical transition radiation. We present an algorithm to extract the time-resolved momentum distribution. Furthermore, qualitative information about the beam size along the pulse train can be extracted from the image left on a screen by sweeping the beam linearly. We present simulation results that allow us to estimate the applicability.

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-197929 (URN)
Projects
CLIC
Note

Submitted to the CLIC Note series.

Available from: 2013-04-08 Created: 2013-04-07 Last updated: 2013-08-30
5. Performance of parabolic and diffusive OTR screens at the CLIC Test Facility 3
Open this publication in new window or tab >>Performance of parabolic and diffusive OTR screens at the CLIC Test Facility 3
Show others...
2011 (English)In: Proceedings of DIPAC2011, Hamburg, Germany, 2011, 413-415 p.Conference paper, Published paper (Other academic)
Abstract [en]

At the CLIC Test Facility 3, OTR screens are commonly used in beam imaging systems for energy and energy spread characterization in dedicated spectrometer lines. In these lines the horizontal beam size is typically of the order of one centimeter. Already in 2005 a limitation was observed resulting from a strong dependence of the intensity of the light captured by the camera, on the positionon the screen (vignetting). The severity of this effect increases with the electron energy, as the aperture of the optical system is finite and the OTR photons are emitted in asmall cone of 1/γ angle. To mitigate this effect, different shapes and surface polishing of the screens were investigated. Parabolic and diffusive OTR radiators were tested in several spectrometer lines all along the CTF3 complex.The results are presented in this paper.

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-197569 (URN)
Conference
DIPAC 2011, Hamburg, Germany
Available from: 2013-03-27 Created: 2013-03-27 Last updated: 2013-08-30

Open Access in DiVA

fulltext(2422 kB)758 downloads
File information
File name FULLTEXT01.pdfFile size 2422 kBChecksum SHA-512
0f424c1fc9bf1b97b760f0b6772f64aade32e4dc0c69e3174b8ba60134c5f8133a79c7433ebae29318d1b01a5d1eee7fd8447aaa2ec5c09a5352a3d91e48c74f
Type fulltextMimetype application/pdf
Buy this publication >>

Authority records BETA

Olvegård, Maja

Search in DiVA

By author/editor
Olvegård, Maja
By organisation
High Energy Physics
Subatomic Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 758 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 693 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf