IBIC2015 - List of Authors (Trad, G.)

Paper	Title	Page
TUCLA03	Design of Coronagraph for the Observation of Beam Halo at LHC	288
	T.M. Mitsuhashi KEK, Ibaraki, Japan E. Bravin, O.R. Jones, F. Roncarolo, H. Schmickler, G. Trad CERN, Geneva, Switzerland
	In the LHC, the beam halo due to higher beam energy and intensities will increase the impact on LHC machine protection and on luminosity performance. Measurement of the beam halo distribution is therefore important for understanding and controlling the beam halo. A coronagraph was designed for the observation of the beam halo population. A new optical design of the coronagraph is made for the halo observation in the LHC. For convenience of masking the core image, we need a large transverse magnification. For this purpose, a telephoto lens arrangement is applied to the adjective lens to extend the focal length to obtain a large transverse magnification. The result of diffraction analysis, the contrast is estimated better than 10⁶. Since the beam halo is estimated to 10⁴ -10⁵ of the core intensity, the coronagraph is estimated to have enough contrast for the observation of beam halo distribution at LHC. This paper describes the detail study of the coronagraph for the LHC for the observation of transverse profile of the beam halo with a contrast down to a level of 10^-6 compared to the peak intensity of the beam core.
	Slides TUCLA03 [15.524 MB]
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WEALA02	First LHC Emittance Measurements at 6.5 TeV	562
	M. Kuhn, F. Antoniou, E. Bravin, B. Dehning, J. Emery, V. Kain, A. Langner, Y. Papaphilippou, E. Piselli, G. Trad CERN, Geneva, Switzerland
	During LHC Run 1 significant transverse emittance growth through the LHC cycle was observed. Measurements indicated most of the blow-up to occur during the injection plateau and the ramp. Intra beam scattering was one of the main drivers of emittance growth. However, finding a good wire scanner working point was difficult. Photomultiplier saturation added uncertainty on all measurements. A large discrepancy between emittances from wire scanners and luminosity was discovered but not solved. During Long Shutdown 1 the wire scanner system was upgraded with new photomultipliers. In April 2015 the LHC re-started with collision energy of 6.5 TeV per beam. This paper presents the first transverse emittance measurements through the LHC Run 2 cycle with low beam intensity. Comparisons with data from the synchrotron light monitors and the LHC experiments will be discussed and results summarized. In addition, a thorough study of wire scanner photomultiplier saturation will be presented. Finally, the emittance growth results will be compared to intra beam scattering simulations.
	Slides WEALA02 [6.752 MB]
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Paper

Title

Page

Design of Coronagraph for the Observation of Beam Halo at LHC

288

T.M. Mitsuhashi
KEK, Ibaraki, Japan
E. Bravin, O.R. Jones, F. Roncarolo, H. Schmickler, G. Trad
CERN, Geneva, Switzerland

In the LHC, the beam halo due to higher beam energy and intensities will increase the impact on LHC machine protection and on luminosity performance. Measurement of the beam halo distribution is therefore important for understanding and controlling the beam halo. A coronagraph was designed for the observation of the beam halo population. A new optical design of the coronagraph is made for the halo observation in the LHC. For convenience of masking the core image, we need a large transverse magnification. For this purpose, a telephoto lens arrangement is applied to the adjective lens to extend the focal length to obtain a large transverse magnification. The result of diffraction analysis, the contrast is estimated better than 10⁶. Since the beam halo is estimated to 10⁴ -10⁵ of the core intensity, the coronagraph is estimated to have enough contrast for the observation of beam halo distribution at LHC. This paper describes the detail study of the coronagraph for the LHC for the observation of transverse profile of the beam halo with a contrast down to a level of 10^-6 compared to the peak intensity of the beam core.

Slides TUCLA03 [15.524 MB]

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reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)

WEALA02

First LHC Emittance Measurements at 6.5 TeV

562

M. Kuhn, F. Antoniou, E. Bravin, B. Dehning, J. Emery, V. Kain, A. Langner, Y. Papaphilippou, E. Piselli, G. Trad
CERN, Geneva, Switzerland

During LHC Run 1 significant transverse emittance growth through the LHC cycle was observed. Measurements indicated most of the blow-up to occur during the injection plateau and the ramp. Intra beam scattering was one of the main drivers of emittance growth. However, finding a good wire scanner working point was difficult. Photomultiplier saturation added uncertainty on all measurements. A large discrepancy between emittances from wire scanners and luminosity was discovered but not solved. During Long Shutdown 1 the wire scanner system was upgraded with new photomultipliers. In April 2015 the LHC re-started with collision energy of 6.5 TeV per beam. This paper presents the first transverse emittance measurements through the LHC Run 2 cycle with low beam intensity. Comparisons with data from the synchrotron light monitors and the LHC experiments will be discussed and results summarized. In addition, a thorough study of wire scanner photomultiplier saturation will be presented. Finally, the emittance growth results will be compared to intra beam scattering simulations.

Slides WEALA02 [6.752 MB]

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reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)