IPAC2015 - List of Authors (Costa Pinto, P.)

Paper	Title	Page
MOPJE070	Reduction of Electron Cloud in Particle Accelerator Beampipes Studied by RF Multipacting	472
	R. Leber, F. Caspers, P. Costa Pinto, M. Taborelli CERN, Geneva, Switzerland
	For a given beam structure, chamber geometry and magnetic field configuration, the electron cloud (EC) intensity depends on the Secondary Electron Yield (SEY) of the beam pipe. The reduction of the EC density as a function of machine operation time (scrubbing) is attributed to the growth of a low SEY carbon film induced by electron bombardment. In this paper, we study the time evolution of the conditioning of stainless steel beam pipes in a laboratory setup. The EC or multipacting is induced by Radio-Frequency (RF) fields in a coaxial resonator under vacuum. Strip detectors are used to monitor the current of the EC. Induced pressure rise is simultaneously detected. The multipacting intensity shows a linear dependence on the positive DC bias voltage up to 1000 V, applied to the central electrode. An accelerated conditioning is observed for the applied bias voltage. The SEY of samples exposed to the EC is measured and the surface composition is monitored by X-ray Photoelectron Spectroscopy. The measured SEY, surface composition and multipacting behaviour are well correlated. The injection of acetylene and dodecane during multipacting proved to be ineffective in the conditioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE070
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WEPHA006	Recommissioning of the COLDEX Experiment at CERN	3109
	R. Salemme, V. Baglin, F. Bellorini, G. Bregliozzi, K. Brodzinski, P. Chiggiato, P. Costa Pinto, P. Gomes, A. Gutierrez, V. Inglese, B. Jenninger, R. Kersevan, E. Michel, M. Pezzetti, B. Rio, A. Sapountzis CERN, Geneva, Switzerland
	COLDEX (Cold bore Experiment), installed in the Super Proton Synchrotron (SPS) at CERN, is a test vacuum sector used in 2001-2004 to validate the Large Hadron Collider (LHC) cryogenic vacuum system with LHC type proton beams. Its cryostat houses a 2.2 m long copper perforated beam screen surrounded by a stainless steel cold bore, both individually temperature controlled down to 5 and 3 K, respectively. In the framework of the development for the High Luminosity upgrade of the LHC (HL-LHC), COLDEX has been re-commissioned in 2014. The objective of this re-commissioning is the validation of the performance of amorphous carbon coatings at cryogenic temperature with LHC type beams. The existing COLDEX beam screen has been dismounted and carbon coated, while a complete overhaul of the vacuum, cryogenic and control systems has been carried out. This contribution describes the phases of re-commissioning and reviews the current experimental set-up. An overview of the possible measurements with COLDEX, in view of its HL-LHC experimental program, is also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA006
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WEPHA019	Development and Production of Non-evaporable Getter Coatings for MAX IV	3145
	P. Costa Pinto, B. Bártová, B. Holliger, S. Marques Dos Santos, V. Nistor, A. Sapountzis, M. Taborelli, I. Wevers CERN, Geneva, Switzerland J. Ahlbäck, E. Al-Dmour, M.J. Grabski, C. Pasquino MAX-lab, Lund, Sweden
	MAX IV is presently under construction at Lund, Sweden, and the first beam for the production of synchrotron radiation is expected to circulate in 2016. The whole set of 3-GeV ring beam pipes is coated with Ti-Zr-V Non Evaporable Getter (NEG) thin film in order to fulfil the average pressure requirement of 1x10^-9 mbar, despite the compact magnet layout and the large aspect ratio of the vacuum chambers. In this work, we present the optimisations of the coating process performed at CERN to coat different geometries and mechanical assembling used for the MAX IV vacuum chambers; the morphology of the thin films is analysed by Scanning Electron Microscopy; the composition and thickness is measured by Energy Dispersive X-ray analysis; the activation of the NEG thin film is monitored by X-ray Photoemission Spectroscopy; the vacuum performance of the coated beam pipes is evaluated by the measurement of hydrogen sticking coefficient. The results of the coating production characterisation for the 84 units coated at CERN are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA019
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WEPHA020	Titanium Coating of Ceramics for Accelerator Applications	3148
	W. Vollenberg, P. Costa Pinto, B. Holliger, A. Sapountzis, M. Taborelli CERN, Geneva, Switzerland
	Titanium thin films can be deposited on ceramics, in particular alumina, without adherence problems. Even after air exposure their secondary electron yield is low compared to alumina and can be further reduced by conditioning or beam scrubbing. In addition, depending on the film thickness, titanium provides different surface resistances that fulfil requirements of ceramics in particle accelerators. Titanium thin films (MOhm square range) are used to suppress electron multipacting and evacuate charges from ceramic surfaces. Thicker films (5-25 Ω square range) are applied to lower the surface resistance so that the beam impedance is reduced. In this contribution, we present the results of a development aimed at coating 2-meter long alumina vacuum chambers with a uniform surface resistivity by a dedicated DC magnetron sputtering configuration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA020
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Paper

Title

Page

Reduction of Electron Cloud in Particle Accelerator Beampipes Studied by RF Multipacting

472

R. Leber, F. Caspers, P. Costa Pinto, M. Taborelli
CERN, Geneva, Switzerland

For a given beam structure, chamber geometry and magnetic field configuration, the electron cloud (EC) intensity depends on the Secondary Electron Yield (SEY) of the beam pipe. The reduction of the EC density as a function of machine operation time (scrubbing) is attributed to the growth of a low SEY carbon film induced by electron bombardment. In this paper, we study the time evolution of the conditioning of stainless steel beam pipes in a laboratory setup. The EC or multipacting is induced by Radio-Frequency (RF) fields in a coaxial resonator under vacuum. Strip detectors are used to monitor the current of the EC. Induced pressure rise is simultaneously detected. The multipacting intensity shows a linear dependence on the positive DC bias voltage up to 1000 V, applied to the central electrode. An accelerated conditioning is observed for the applied bias voltage. The SEY of samples exposed to the EC is measured and the surface composition is monitored by X-ray Photoelectron Spectroscopy. The measured SEY, surface composition and multipacting behaviour are well correlated. The injection of acetylene and dodecane during multipacting proved to be ineffective in the conditioning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE070

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA006

Recommissioning of the COLDEX Experiment at CERN

3109

R. Salemme, V. Baglin, F. Bellorini, G. Bregliozzi, K. Brodzinski, P. Chiggiato, P. Costa Pinto, P. Gomes, A. Gutierrez, V. Inglese, B. Jenninger, R. Kersevan, E. Michel, M. Pezzetti, B. Rio, A. Sapountzis
CERN, Geneva, Switzerland

COLDEX (Cold bore Experiment), installed in the Super Proton Synchrotron (SPS) at CERN, is a test vacuum sector used in 2001-2004 to validate the Large Hadron Collider (LHC) cryogenic vacuum system with LHC type proton beams. Its cryostat houses a 2.2 m long copper perforated beam screen surrounded by a stainless steel cold bore, both individually temperature controlled down to 5 and 3 K, respectively. In the framework of the development for the High Luminosity upgrade of the LHC (HL-LHC), COLDEX has been re-commissioned in 2014. The objective of this re-commissioning is the validation of the performance of amorphous carbon coatings at cryogenic temperature with LHC type beams. The existing COLDEX beam screen has been dismounted and carbon coated, while a complete overhaul of the vacuum, cryogenic and control systems has been carried out. This contribution describes the phases of re-commissioning and reviews the current experimental set-up. An overview of the possible measurements with COLDEX, in view of its HL-LHC experimental program, is also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA019

Development and Production of Non-evaporable Getter Coatings for MAX IV

3145

P. Costa Pinto, B. Bártová, B. Holliger, S. Marques Dos Santos, V. Nistor, A. Sapountzis, M. Taborelli, I. Wevers
CERN, Geneva, Switzerland
J. Ahlbäck, E. Al-Dmour, M.J. Grabski, C. Pasquino
MAX-lab, Lund, Sweden

MAX IV is presently under construction at Lund, Sweden, and the first beam for the production of synchrotron radiation is expected to circulate in 2016. The whole set of 3-GeV ring beam pipes is coated with Ti-Zr-V Non Evaporable Getter (NEG) thin film in order to fulfil the average pressure requirement of 1x10^-9 mbar, despite the compact magnet layout and the large aspect ratio of the vacuum chambers. In this work, we present the optimisations of the coating process performed at CERN to coat different geometries and mechanical assembling used for the MAX IV vacuum chambers; the morphology of the thin films is analysed by Scanning Electron Microscopy; the composition and thickness is measured by Energy Dispersive X-ray analysis; the activation of the NEG thin film is monitored by X-ray Photoemission Spectroscopy; the vacuum performance of the coated beam pipes is evaluated by the measurement of hydrogen sticking coefficient. The results of the coating production characterisation for the 84 units coated at CERN are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPHA020

Titanium Coating of Ceramics for Accelerator Applications

3148

W. Vollenberg, P. Costa Pinto, B. Holliger, A. Sapountzis, M. Taborelli
CERN, Geneva, Switzerland

Titanium thin films can be deposited on ceramics, in particular alumina, without adherence problems. Even after air exposure their secondary electron yield is low compared to alumina and can be further reduced by conditioning or beam scrubbing. In addition, depending on the film thickness, titanium provides different surface resistances that fulfil requirements of ceramics in particle accelerators. Titanium thin films (MOhm square range) are used to suppress electron multipacting and evacuate charges from ceramic surfaces. Thicker films (5-25 Ω square range) are applied to lower the surface resistance so that the beam impedance is reduced. In this contribution, we present the results of a development aimed at coating 2-meter long alumina vacuum chambers with a uniform surface resistivity by a dedicated DC magnetron sputtering configuration.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA020

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)