IPAC2016 - List of Authors (Chiggiato, P.)

Paper	Title	Page
MOPOR008	Beam Induced RF Heating in LHC in 2015	602
	B. Salvant, O. Aberle, M. Albert, R. Alemany-Fernandez, G. Arduini, J. Baechler, M.J. Barnes, P. Baudrenghien, O.E. Berrig, N. Biancacci, G. Bregliozzi, J.V. Campelo, F. Carra, F. Caspers, P. Chiggiato, A. Danisi, H.A. Day, M. Deile, D. Druzhkin, J.F. Esteban Müller, S. Jakobsen, J. Kuczerowski, A. Lechner, R. Losito, A. Masi, N. Minafra, E. Métral, A.A. Nosych, A. Perillo Marcone, D. Perini, S. Redaelli, F. Roncarolo, G. Rumolo, E.N. Shaposhnikova, J.A. Uythoven, C. Vollinger, A.J. Välimaa, N. Wang, M. Wendt, J. Wenninger, C. Zannini CERN, Geneva, Switzerland M. Bozzo INFN Genova, Genova, Italy J.F. Esteban Müller EPFL, Lausanne, Switzerland N. Wang IHEP, Beijing, People's Republic of China
	Following the recurrent beam induced RF issues that perturbed LHC operation during LHC Run 1, a series of actions were put in place to minimize the risk that similar issues would occur in LHC Run 2: longitudinal impedance reduction campaign and/or improvement of cooling for equipment that were problematic or at the limit during Run 1, stringent constraints enforced on new equipment that would be installed in the machine, tests to control the bunch length and longitudinal distribution, additional monitoring of temperature, new monitoring tools and warning chains. This contribution reports the outcome of these actions, both successes as well as shortcomings, and details the lessons learnt for the future runs.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR008
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THPMY007	Vacuum Performance of Amorphous Carbon Coating at Cryogenic Temperature with Presence of Proton Beams	3663
	R. Salemme, V. Baglin, G. Bregliozzi, P. Chiggiato CERN, Geneva, Switzerland
	Amorphous carbon (a-C) coating is the baseline electron multipacting mitigation strategy proposed for the Inner Triplets (IT) in the High Luminosity upgrade of the Large Hadron Collider (HL-LHC). As of 2014, the COLD bore EXperiment (COLDEX) is qualifying the performance of a-C coating at cryogenic temperature in a LHC type cryogenic vacuum system. In this paper, the experimental results following a cryogenic vacuum characterization of a-C coating in the 5 to 150 K temperature range are reviewed. We discuss the dynamic pressure rise, gas composition, dissipated heat load and electron activity observed within an accumulated beam time of 9 Ah. The results of dedicated experiments including pre-adsorption of different gas species (H2, CO) on the a-C coating are discussed. Based of phenomenological modeling, up-to-date secondary emission input parameters for a-C coatings are retrieved for electron cloud build-up simulations. Finally, first implications for the HL-LHC ITs design are drawn.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY007
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THPMY008	Mechanical and Vacuum Stability Studies for the LHC Experiments Upgrade	3667
	J. Sestak, G. Bregliozzi, P. Chiggiato CERN, Geneva, Switzerland
	In April 2015, the Large Hadron Collider (LHC) has entered its second operational period that will last for 3 years with expected end of the operations at the beginning of 2019. Afterward, the LHC will undergo a long shutdown (LS2) for upgrade and maintenance. The four LHC experiments, ATLAS, ALICE, CMS and LHCb, will experience an important upgrade too. From the design point of view, the LS2 experimental beam vacuum upgrade requires multi-disciplinary approach: based on the geometrical envelope defined by experiment, the vacuum chambers size and shape must be optimized. This included Monte Carlo pressure profile simulations and vacuum stability studies in order to meet the specific pressure requests in the interaction region. Together with vacuum studies the structural analysis are performed in order to optimise chambers thickness and position of the operational and maintenance supports. The material selection for vacuum chambers in the experimental area follows the CERN ALARA (as low as reasonably achievable) principle. This paper gives an overview of the LS2 experimental vacuum sectors upgrades. The most extensive design studies, done for the two experiments CMS and ALICE are discussed in detail.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY008
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THPMY010	LHC Beam Vacuum Evolution During 2015 Machine Operation	3673
	C. Yin Vallgren, G. Bregliozzi, P. Chiggiato CERN, Geneva, Switzerland
	The LHC successfully returned to operation in April, 2015 after almost 2 years of Long Shutdown 1 (LS1) for various upgrade and consolidation programs. During 2015 operation, the LHC operated for more than 1000 fills. The 2015 LHC proton physics ended with 2244 bunches per beam circulating with 25 ns bunch spacing at top energy of 6.5 TeV. This paper summarizes the dynamic vacuum observations in different locations along the LHC during dedicated fills as well as during physics runs with both 50 ns and 25 ns bunch spacing. The causes for the dynamic pressure rises are investigated and are presented. A clear beam conditioning effect is observed, as well as a so-called de-conditioning effect. Furthermore, for the experimental areas, the dynamic pressure evolution is also presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY010
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Paper

Title

Page

Beam Induced RF Heating in LHC in 2015

602

B. Salvant, O. Aberle, M. Albert, R. Alemany-Fernandez, G. Arduini, J. Baechler, M.J. Barnes, P. Baudrenghien, O.E. Berrig, N. Biancacci, G. Bregliozzi, J.V. Campelo, F. Carra, F. Caspers, P. Chiggiato, A. Danisi, H.A. Day, M. Deile, D. Druzhkin, J.F. Esteban Müller, S. Jakobsen, J. Kuczerowski, A. Lechner, R. Losito, A. Masi, N. Minafra, E. Métral, A.A. Nosych, A. Perillo Marcone, D. Perini, S. Redaelli, F. Roncarolo, G. Rumolo, E.N. Shaposhnikova, J.A. Uythoven, C. Vollinger, A.J. Välimaa, N. Wang, M. Wendt, J. Wenninger, C. Zannini
CERN, Geneva, Switzerland
M. Bozzo
INFN Genova, Genova, Italy
J.F. Esteban Müller
EPFL, Lausanne, Switzerland
N. Wang
IHEP, Beijing, People's Republic of China

Following the recurrent beam induced RF issues that perturbed LHC operation during LHC Run 1, a series of actions were put in place to minimize the risk that similar issues would occur in LHC Run 2: longitudinal impedance reduction campaign and/or improvement of cooling for equipment that were problematic or at the limit during Run 1, stringent constraints enforced on new equipment that would be installed in the machine, tests to control the bunch length and longitudinal distribution, additional monitoring of temperature, new monitoring tools and warning chains. This contribution reports the outcome of these actions, both successes as well as shortcomings, and details the lessons learnt for the future runs.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR008

Export •

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

THPMY007

Vacuum Performance of Amorphous Carbon Coating at Cryogenic Temperature with Presence of Proton Beams

3663

R. Salemme, V. Baglin, G. Bregliozzi, P. Chiggiato
CERN, Geneva, Switzerland

Amorphous carbon (a-C) coating is the baseline electron multipacting mitigation strategy proposed for the Inner Triplets (IT) in the High Luminosity upgrade of the Large Hadron Collider (HL-LHC). As of 2014, the COLD bore EXperiment (COLDEX) is qualifying the performance of a-C coating at cryogenic temperature in a LHC type cryogenic vacuum system. In this paper, the experimental results following a cryogenic vacuum characterization of a-C coating in the 5 to 150 K temperature range are reviewed. We discuss the dynamic pressure rise, gas composition, dissipated heat load and electron activity observed within an accumulated beam time of 9 Ah. The results of dedicated experiments including pre-adsorption of different gas species (H2, CO) on the a-C coating are discussed. Based of phenomenological modeling, up-to-date secondary emission input parameters for a-C coatings are retrieved for electron cloud build-up simulations. Finally, first implications for the HL-LHC ITs design are drawn.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY007

Export •

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

THPMY008

Mechanical and Vacuum Stability Studies for the LHC Experiments Upgrade

3667

J. Sestak, G. Bregliozzi, P. Chiggiato
CERN, Geneva, Switzerland

In April 2015, the Large Hadron Collider (LHC) has entered its second operational period that will last for 3 years with expected end of the operations at the beginning of 2019. Afterward, the LHC will undergo a long shutdown (LS2) for upgrade and maintenance. The four LHC experiments, ATLAS, ALICE, CMS and LHCb, will experience an important upgrade too. From the design point of view, the LS2 experimental beam vacuum upgrade requires multi-disciplinary approach: based on the geometrical envelope defined by experiment, the vacuum chambers size and shape must be optimized. This included Monte Carlo pressure profile simulations and vacuum stability studies in order to meet the specific pressure requests in the interaction region. Together with vacuum studies the structural analysis are performed in order to optimise chambers thickness and position of the operational and maintenance supports. The material selection for vacuum chambers in the experimental area follows the CERN ALARA (as low as reasonably achievable) principle. This paper gives an overview of the LS2 experimental vacuum sectors upgrades. The most extensive design studies, done for the two experiments CMS and ALICE are discussed in detail.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY008

Export •

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

THPMY010

LHC Beam Vacuum Evolution During 2015 Machine Operation

3673

C. Yin Vallgren, G. Bregliozzi, P. Chiggiato
CERN, Geneva, Switzerland

The LHC successfully returned to operation in April, 2015 after almost 2 years of Long Shutdown 1 (LS1) for various upgrade and consolidation programs. During 2015 operation, the LHC operated for more than 1000 fills. The 2015 LHC proton physics ended with 2244 bunches per beam circulating with 25 ns bunch spacing at top energy of 6.5 TeV. This paper summarizes the dynamic vacuum observations in different locations along the LHC during dedicated fills as well as during physics runs with both 50 ns and 25 ns bunch spacing. The causes for the dynamic pressure rises are investigated and are presented. A clear beam conditioning effect is observed, as well as a so-called de-conditioning effect. Furthermore, for the experimental areas, the dynamic pressure evolution is also presented.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY010

Export •

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