IPAC2016 - List of Authors (Uythoven, J.A.)

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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MOPOR010	Impedance Measurements and Simulations on the TCTP and TDI LHC Collimators	610
	N. Biancacci, F. Caspers, A. Grudiev, J. Kuczerowski, I. Lamas Garcia, A. Lechner, E. Métral, A. Passarelli, A. Perillo Marcone, B. Salvant, J.A. Uythoven CERN, Geneva, Switzerland O. Frasciello, M. Zobov INFN/LNF, Frascati (Roma), Italy A. Mostacci Rome University La Sapienza, Roma, Italy N. Mounet EPFL, Lausanne, Switzerland
	The LHC collimation system is a critical element for the safe operation of the LHC machine and is subject to continuous performance monitoring, hardware upgrade and optimization. In this work we will address the impact on impedance of the upgrades performed on the TDI injection protection collimator, where the absorber material has been changed to mitigate the device heating observed in machine operation, and on selected secondary (TCS) and tertiary (TCT) collimators, where beam position monitors (BPM) have been embedded for faster jaw alignment. Concerning the TDI, we will present the RF measurements performed before and after the upgrade, comparing the result to heating and tune shift beam measurements. For the TCTs, we will study how the higher order modes (HOM) introduced by the BPM addition have been cured by means of ferrite placement in the device. The impedance mitigation campaign has been supported by RF measurements whose results are in good agreement with GdfidL and CST simulations. The presence of undamped low frequency modes is proved not to be detrimental to the safe LHC operation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR010
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TUPMB052	High Intensity Beam Test of Low Z Materials for the Upgrade of SPS-to-LHC Transfer Line Collimators and LHC Injection Absorbers	1218
	F.L. Maciariello, O. Aberle, M.E.J. Butcher, M. Calviani, R. Folch, V. Kain, K. Karagiannis, I. Lamas Garcia, A. Lechner, F.-X. Nuiry, G.E. Steele, J.A. Uythoven CERN, Geneva, Switzerland
	In the framework of the LHC Injector Upgrade (LIU) and High-Luminosity LHC (HL-LHC) project, the collimators in the SPS-to LHC transfer lines will undergo important modifications. The changes to these collimators will allow them to cope with beam brightness and intensity levels much increased with respect to their original design parameters: nominal and ultimate LHC. The necessity for replacement of the current materials will need to be confirmed by a test in the High Radiation to Materials (HRM) facility at CERN. This test will involve low Z materials (such as Graphite and 3-D Carbon/Carbon composite), and will recreate the worst case scenario those materials could see when directly impacted by High luminosity LHC (HL-LHC) or Batch Compression Merging and Splitting (BCMS) beams. Thermo-structural simulations used for the material studies and research, the experiment preparation phase, the experiment itself, pre irradiation analysis (including ultrasound and metrology tests on the target materials), the results and their correlation with numerical simulations will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB052
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TUPMR048	SPS Injection and Beam Quality for LHC Heavy Ions With 150 ns Kicker Rise Time	1360
	B. Goddard, E. Carlier, L. Ducimetière, G. Kotzian, J.A. Uythoven CERN, Geneva, Switzerland F.M. Velotti EPFL, Lausanne, Switzerland
	As part of the LHC Injectors Upgrade project for LHC heavy ions, the SPS injection kicker system rise time needs reduction below its present 225 ns. One technically challenging option under consideration is the addition of fast Pulse Forming Lines in parallel to the existing Pulse Forming Networks for the 12 kicker magnets MKP-S, targeting a system field rise time of 100 ns. An alternative option is to optimise the system to approach the existing individual magnet field rise time (2-98%) of 150 ns. This would still significantly increase the number of colliding bunches in LHC while minimising the cost and effort of the system upgrade. The observed characteristics of the present system are described, compared to the expected system rise time, together with results of simulations and measurements with 175 and 150 ns injection batch spacing. The expected beam quality at injection into LHC is quantified, with the emittance growth and simulated tail population taking into account expected jitter and synchronisation errors, damper performance and SPS non-linear optics behavior. The outlook for deployment is discussed, with the implications for LHC operation and HL-LHC performance.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR048
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TUPMW027	The 2015 Heavy-Ion Run of the LHC	1493
	J.M. Jowett, R. Alemany-Fernandez, R. Bruce, M. Giovannozzi, P.D. Hermes, W. Höfle, M. Lamont, T. Mertens, S. Redaelli, M. Schaumann, J.A. Uythoven, J. Wenninger CERN, Geneva, Switzerland
	In late 2015 the LHC collided lead nuclei at a beam energy of 6.37 Z TeV, chosen to match the 5.02 TeV per colliding nucleon pair of the p-Pb collision run in 2013. In so doing, it surpassed its design luminosity by a factor of 2. Besides the higher energy, the operational configuration had a number of new features with respect to the previous Pb-Pb run at 3.5 Z TeV in 2011; unusual bunch patterns providing collisions in the LHCb experiment for the first time, luminosity levelling and sharing requirements, a vertical displacement of the interaction point in the ALICE experiment, and operation closer to magnet quench limits with mitigation measures. We present a summary of the commissioning and operation and what has been learned in view of future heavy-ion operation at higher luminosity.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW027
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WEOCA01	Operation of the LHC with Protons at High Luminosity and High Energy	2066
	G. Papotti, M. Albert, R. Alemany-Fernandez, G.E. Crockford, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, D. Jacquet, M. Lamont, D. Nisbet, L. Normann, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli Camillocci, R. Suykerbuyk, J.A. Uythoven, J. Wenninger CERN, Geneva, Switzerland
	In 2015 the Large Hadron Collider (LHC) entered the first year in its second long Run, after a 2-year shutdown that prepared it for high energy. The first two months of beam operation were dedicated to setting up the nominal cycle for proton-proton operation at 6.5 TeV/beam, and culminated with the first physics with 3 nominal bunches/ring at 13 TeV CoM on 3 June. The year continued with a stepwise intensity ramp up that allowed reaching 2244 bunches/ring for a peak luminosity of ~5·10³³ cm^-2s⁻¹ and a total of just above 4 fb-1 delivered to the high luminosity experiments. Beam operation was shaped by the high intensity effects, e.g. electron cloud and macroparticle-induced fast losses (UFOs), which on a few occasions caused the first beam induced quenches at high energy. This paper describes the operational experience with high intensity and high energy at the LHC, together with the issues that had to be tackled along the way.
	Slides WEOCA01 [4.013 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOCA01
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THPMW030	Studies of Impedance-related Improvements of the SPS Injection Kicker System	3611
	M.J. Barnes, A. Adraktas, M.S. Beck, G. Bregliozzi, H.A. Day, L. Ducimetière, J.A. Ferreira Somoza, B. Goddard, T. Kramer, C. Pasquino, G. Rumolo, B. Salvant, L. Sermeus, J.A. Uythoven, L. Vega Cid, W.J.M. Weterings, C. Zannini CERN, Geneva, Switzerland F.M. Velotti EPFL, Lausanne, Switzerland
	The injection kicker system for the SPS consists of sixteen magnets housed in a total of four vacuum tanks. The kicker magnets in one tank have recently limited operation of the SPS with high-intensity beam: this is due to both beam induced heating in the ferrite yoke of the kicker magnets and abnormally high pressure in the vacuum tank. Furthermore, operation with the higher intensity beams needed in the future for HL-LHC is expected to exacerbate these problems. Hence studies of the longitudinal beam coupling impedance of the kicker magnets have been carried out to investigate effective methods to shield the ferrite yoke from the circulating beam. The shielding must not compromise the field quality or high voltage behaviour of the kicker magnets and should not significantly reduce the beam aperture: results of these studies, together with measurements, are presented. In addition results of tests to identify the causes of abnormal outgassing are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW030
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THPMW033	Operational Experience of the Upgraded LHC Injection Kicker Magnets	3623
	M.J. Barnes, A. Adraktas, G. Bregliozzi, S. Calatroni, H.A. Day, L. Ducimetière, B. Goddard, V. Gomes Namora, V. Mertens, B. Salvant, J.A. Uythoven, L. Vega Cid, W.J.M. Weterings, C. Yin Vallgren CERN, Geneva, Switzerland
	During Run 1 of the LHC the injection kicker magnets caused occasional operational delays due to beam induced heating with high bunch intensity and short bunch lengths. In addition, sometimes there were also sporadic issues with microscopic unidentified falling objects, vacuum activity and electrical flashover of the injection kickers. An extensive program of studies was launched and significant upgrades were carried out during long shutdown 1. These upgrades include a new design of a beam screen to both reduce the beam coupling impedance of the kicker magnet, and to significantly reduce the electric field associated with the screen conductors, hence decreasing the probability of electrical breakdown in this region. In addition new cleaning procedures were implemented and equipment adjacent to the injection kickers and various vacuum components were modified. This paper presents operational experience of the injection kicker magnets during Run 2 of the LHC and assesses the effectiveness of the various upgrades.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW033
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THPMY019	LHC Injection Protection Devices, Thermo-mechanical Studies through the Design Phase	3698
	I. Lamas Garcia, N. Biancacci, G. Bregliozzi, M. Calviani, M.I. Frankl, L. Gentini, S.S. Gilardoni, A. Lechner, A. Perillo-Marcone, B. Salvant, N.V. Shetty, J.A. Uythoven CERN, Geneva, Switzerland
	The TDI is a beam intercepting device installed on the two injection lines of the LHC. Its function is to protect the superconducting machine elements during injection in the case of a malfunction of the injection kickers. The TDIS, which will replace the TDI, is foreseen to be installed for high luminosity operation. Due to the higher bunch intensities and smaller beam emittances expected, and following the operational experiences of the TDI, a complete revision of the design of the jaws must be performed, with a main focus on the material selection. Furthermore, the new TDIS will also improve the TDI reliability by means of a robust design of the jaw positioning mechanism, the efficiency of the cooling circuit and by reducing its impedance. A simplified installation procedure and maintenance will also be an important requirement for the new design. This paper introduces the main characteristics of the TDI as LHC injection protection device, showing the needs and requirements for its upgrade. It also discusses the thermo-mechanical simulations that are supporting and guiding the design phase and the material selection, and describes the modifications to be implemented, so far, for this new device.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY019
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THPOR052	A Beam-based Measurement of the LHC Beam Dump Kicker Waveform	3911
	M.A. Fraser, W. Bartmann, C. Bracco, E. Carlier, B. Goddard, V. Kain, N. Magnin, J.A. Uythoven, F.M. Velotti CERN, Geneva, Switzerland
	The increase of the LHC collision energy to 13 TeV after Long Shutdown 1 has doubled the operational energy range of the LHC beam dump system (LBDS) during Run 2. In preparation for the safe operation of the LHC, the waveform of the LBDS extraction kicker was measured using beam-based measurements for the first time during the machine's re-commissioning period. The measurements provide a reference for a more precise synchronisation of the dump system and abort-gap timing, and provide an independent check of the system's calibration. The precision of the beam-based technique allowed the necessary adjustments to the LBDS trigger delays to ensure the synchronous firing of the LBDS at all beam energies up to 6.5 TeV. In this paper the measurement and simulation campaign is described and the performance of the system reported.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR052
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THPOY045	Commissioning of the Machine Protection Systems of the Large Hadron Collider Following its First Long Shutdown	4203
	D. Wollmann, R. Schmidt, J.A. Uythoven, J. Wenninger, M. Zerlauth CERN, Geneva, Switzerland
	During the first long shutdown of the Large Hadron Collider (LHC) extending for more than 18 months, most Machine Protection Systems (MPS) have undergone significant changes, and upgrades. A full re-commissioning of the MPS was performed at the end of the shutdown and during the LHC beam commissioning in 2015. To verify the correct functioning of all protection-relevant systems with beam, a step-wise intensity ramp-up was performed, reaching at the end of 2015 a record stored beam energy of ~280 MJ per beam, nearly 80% of the value in the design report. This contribution summarizes the results of the MPS commissioning, the intensity ramp-up and the continuous follow-up during operation, focusing mainly on near misses and false triggers and their proposed mitigations. A strategy to minimize risks during machine development periods for future operation of the LHC, when the protection parameters are modified for several tests, is discussed. The machine protection strategy for the LHC run in 2016 is presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY045
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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.

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

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MOPOR010

Impedance Measurements and Simulations on the TCTP and TDI LHC Collimators

610

N. Biancacci, F. Caspers, A. Grudiev, J. Kuczerowski, I. Lamas Garcia, A. Lechner, E. Métral, A. Passarelli, A. Perillo Marcone, B. Salvant, J.A. Uythoven
CERN, Geneva, Switzerland
O. Frasciello, M. Zobov
INFN/LNF, Frascati (Roma), Italy
A. Mostacci
Rome University La Sapienza, Roma, Italy
N. Mounet
EPFL, Lausanne, Switzerland

The LHC collimation system is a critical element for the safe operation of the LHC machine and is subject to continuous performance monitoring, hardware upgrade and optimization. In this work we will address the impact on impedance of the upgrades performed on the TDI injection protection collimator, where the absorber material has been changed to mitigate the device heating observed in machine operation, and on selected secondary (TCS) and tertiary (TCT) collimators, where beam position monitors (BPM) have been embedded for faster jaw alignment. Concerning the TDI, we will present the RF measurements performed before and after the upgrade, comparing the result to heating and tune shift beam measurements. For the TCTs, we will study how the higher order modes (HOM) introduced by the BPM addition have been cured by means of ferrite placement in the device. The impedance mitigation campaign has been supported by RF measurements whose results are in good agreement with GdfidL and CST simulations. The presence of undamped low frequency modes is proved not to be detrimental to the safe LHC operation.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR010

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TUPMB052

High Intensity Beam Test of Low Z Materials for the Upgrade of SPS-to-LHC Transfer Line Collimators and LHC Injection Absorbers

1218

F.L. Maciariello, O. Aberle, M.E.J. Butcher, M. Calviani, R. Folch, V. Kain, K. Karagiannis, I. Lamas Garcia, A. Lechner, F.-X. Nuiry, G.E. Steele, J.A. Uythoven
CERN, Geneva, Switzerland

In the framework of the LHC Injector Upgrade (LIU) and High-Luminosity LHC (HL-LHC) project, the collimators in the SPS-to LHC transfer lines will undergo important modifications. The changes to these collimators will allow them to cope with beam brightness and intensity levels much increased with respect to their original design parameters: nominal and ultimate LHC. The necessity for replacement of the current materials will need to be confirmed by a test in the High Radiation to Materials (HRM) facility at CERN. This test will involve low Z materials (such as Graphite and 3-D Carbon/Carbon composite), and will recreate the worst case scenario those materials could see when directly impacted by High luminosity LHC (HL-LHC) or Batch Compression Merging and Splitting (BCMS) beams. Thermo-structural simulations used for the material studies and research, the experiment preparation phase, the experiment itself, pre irradiation analysis (including ultrasound and metrology tests on the target materials), the results and their correlation with numerical simulations will be presented.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB052

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TUPMR048

SPS Injection and Beam Quality for LHC Heavy Ions With 150 ns Kicker Rise Time

1360

B. Goddard, E. Carlier, L. Ducimetière, G. Kotzian, J.A. Uythoven
CERN, Geneva, Switzerland
F.M. Velotti
EPFL, Lausanne, Switzerland

As part of the LHC Injectors Upgrade project for LHC heavy ions, the SPS injection kicker system rise time needs reduction below its present 225 ns. One technically challenging option under consideration is the addition of fast Pulse Forming Lines in parallel to the existing Pulse Forming Networks for the 12 kicker magnets MKP-S, targeting a system field rise time of 100 ns. An alternative option is to optimise the system to approach the existing individual magnet field rise time (2-98%) of 150 ns. This would still significantly increase the number of colliding bunches in LHC while minimising the cost and effort of the system upgrade. The observed characteristics of the present system are described, compared to the expected system rise time, together with results of simulations and measurements with 175 and 150 ns injection batch spacing. The expected beam quality at injection into LHC is quantified, with the emittance growth and simulated tail population taking into account expected jitter and synchronisation errors, damper performance and SPS non-linear optics behavior. The outlook for deployment is discussed, with the implications for LHC operation and HL-LHC performance.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR048

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TUPMW027

The 2015 Heavy-Ion Run of the LHC

1493

J.M. Jowett, R. Alemany-Fernandez, R. Bruce, M. Giovannozzi, P.D. Hermes, W. Höfle, M. Lamont, T. Mertens, S. Redaelli, M. Schaumann, J.A. Uythoven, J. Wenninger
CERN, Geneva, Switzerland

In late 2015 the LHC collided lead nuclei at a beam energy of 6.37 Z TeV, chosen to match the 5.02 TeV per colliding nucleon pair of the p-Pb collision run in 2013. In so doing, it surpassed its design luminosity by a factor of 2. Besides the higher energy, the operational configuration had a number of new features with respect to the previous Pb-Pb run at 3.5 Z TeV in 2011; unusual bunch patterns providing collisions in the LHCb experiment for the first time, luminosity levelling and sharing requirements, a vertical displacement of the interaction point in the ALICE experiment, and operation closer to magnet quench limits with mitigation measures. We present a summary of the commissioning and operation and what has been learned in view of future heavy-ion operation at higher luminosity.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW027

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WEOCA01

Operation of the LHC with Protons at High Luminosity and High Energy

2066

G. Papotti, M. Albert, R. Alemany-Fernandez, G.E. Crockford, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, D. Jacquet, M. Lamont, D. Nisbet, L. Normann, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli Camillocci, R. Suykerbuyk, J.A. Uythoven, J. Wenninger
CERN, Geneva, Switzerland

In 2015 the Large Hadron Collider (LHC) entered the first year in its second long Run, after a 2-year shutdown that prepared it for high energy. The first two months of beam operation were dedicated to setting up the nominal cycle for proton-proton operation at 6.5 TeV/beam, and culminated with the first physics with 3 nominal bunches/ring at 13 TeV CoM on 3 June. The year continued with a stepwise intensity ramp up that allowed reaching 2244 bunches/ring for a peak luminosity of ~5·10³³ cm^-2s⁻¹ and a total of just above 4 fb-1 delivered to the high luminosity experiments. Beam operation was shaped by the high intensity effects, e.g. electron cloud and macroparticle-induced fast losses (UFOs), which on a few occasions caused the first beam induced quenches at high energy. This paper describes the operational experience with high intensity and high energy at the LHC, together with the issues that had to be tackled along the way.

Slides WEOCA01 [4.013 MB]

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOCA01

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THPMW030

Studies of Impedance-related Improvements of the SPS Injection Kicker System

3611

M.J. Barnes, A. Adraktas, M.S. Beck, G. Bregliozzi, H.A. Day, L. Ducimetière, J.A. Ferreira Somoza, B. Goddard, T. Kramer, C. Pasquino, G. Rumolo, B. Salvant, L. Sermeus, J.A. Uythoven, L. Vega Cid, W.J.M. Weterings, C. Zannini
CERN, Geneva, Switzerland
F.M. Velotti
EPFL, Lausanne, Switzerland

The injection kicker system for the SPS consists of sixteen magnets housed in a total of four vacuum tanks. The kicker magnets in one tank have recently limited operation of the SPS with high-intensity beam: this is due to both beam induced heating in the ferrite yoke of the kicker magnets and abnormally high pressure in the vacuum tank. Furthermore, operation with the higher intensity beams needed in the future for HL-LHC is expected to exacerbate these problems. Hence studies of the longitudinal beam coupling impedance of the kicker magnets have been carried out to investigate effective methods to shield the ferrite yoke from the circulating beam. The shielding must not compromise the field quality or high voltage behaviour of the kicker magnets and should not significantly reduce the beam aperture: results of these studies, together with measurements, are presented. In addition results of tests to identify the causes of abnormal outgassing are presented.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW030

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THPMW033

Operational Experience of the Upgraded LHC Injection Kicker Magnets

3623

M.J. Barnes, A. Adraktas, G. Bregliozzi, S. Calatroni, H.A. Day, L. Ducimetière, B. Goddard, V. Gomes Namora, V. Mertens, B. Salvant, J.A. Uythoven, L. Vega Cid, W.J.M. Weterings, C. Yin Vallgren
CERN, Geneva, Switzerland

During Run 1 of the LHC the injection kicker magnets caused occasional operational delays due to beam induced heating with high bunch intensity and short bunch lengths. In addition, sometimes there were also sporadic issues with microscopic unidentified falling objects, vacuum activity and electrical flashover of the injection kickers. An extensive program of studies was launched and significant upgrades were carried out during long shutdown 1. These upgrades include a new design of a beam screen to both reduce the beam coupling impedance of the kicker magnet, and to significantly reduce the electric field associated with the screen conductors, hence decreasing the probability of electrical breakdown in this region. In addition new cleaning procedures were implemented and equipment adjacent to the injection kickers and various vacuum components were modified. This paper presents operational experience of the injection kicker magnets during Run 2 of the LHC and assesses the effectiveness of the various upgrades.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW033

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THPMY019

LHC Injection Protection Devices, Thermo-mechanical Studies through the Design Phase

3698

I. Lamas Garcia, N. Biancacci, G. Bregliozzi, M. Calviani, M.I. Frankl, L. Gentini, S.S. Gilardoni, A. Lechner, A. Perillo-Marcone, B. Salvant, N.V. Shetty, J.A. Uythoven
CERN, Geneva, Switzerland

The TDI is a beam intercepting device installed on the two injection lines of the LHC. Its function is to protect the superconducting machine elements during injection in the case of a malfunction of the injection kickers. The TDIS, which will replace the TDI, is foreseen to be installed for high luminosity operation. Due to the higher bunch intensities and smaller beam emittances expected, and following the operational experiences of the TDI, a complete revision of the design of the jaws must be performed, with a main focus on the material selection. Furthermore, the new TDIS will also improve the TDI reliability by means of a robust design of the jaw positioning mechanism, the efficiency of the cooling circuit and by reducing its impedance. A simplified installation procedure and maintenance will also be an important requirement for the new design. This paper introduces the main characteristics of the TDI as LHC injection protection device, showing the needs and requirements for its upgrade. It also discusses the thermo-mechanical simulations that are supporting and guiding the design phase and the material selection, and describes the modifications to be implemented, so far, for this new device.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY019

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THPOR052

A Beam-based Measurement of the LHC Beam Dump Kicker Waveform

3911

M.A. Fraser, W. Bartmann, C. Bracco, E. Carlier, B. Goddard, V. Kain, N. Magnin, J.A. Uythoven, F.M. Velotti
CERN, Geneva, Switzerland

The increase of the LHC collision energy to 13 TeV after Long Shutdown 1 has doubled the operational energy range of the LHC beam dump system (LBDS) during Run 2. In preparation for the safe operation of the LHC, the waveform of the LBDS extraction kicker was measured using beam-based measurements for the first time during the machine's re-commissioning period. The measurements provide a reference for a more precise synchronisation of the dump system and abort-gap timing, and provide an independent check of the system's calibration. The precision of the beam-based technique allowed the necessary adjustments to the LBDS trigger delays to ensure the synchronous firing of the LBDS at all beam energies up to 6.5 TeV. In this paper the measurement and simulation campaign is described and the performance of the system reported.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR052

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THPOY045

Commissioning of the Machine Protection Systems of the Large Hadron Collider Following its First Long Shutdown

4203

D. Wollmann, R. Schmidt, J.A. Uythoven, J. Wenninger, M. Zerlauth
CERN, Geneva, Switzerland

During the first long shutdown of the Large Hadron Collider (LHC) extending for more than 18 months, most Machine Protection Systems (MPS) have undergone significant changes, and upgrades. A full re-commissioning of the MPS was performed at the end of the shutdown and during the LHC beam commissioning in 2015. To verify the correct functioning of all protection-relevant systems with beam, a step-wise intensity ramp-up was performed, reaching at the end of 2015 a record stored beam energy of ~280 MJ per beam, nearly 80% of the value in the design report. This contribution summarizes the results of the MPS commissioning, the intensity ramp-up and the continuous follow-up during operation, focusing mainly on near misses and false triggers and their proposed mitigations. A strategy to minimize risks during machine development periods for future operation of the LHC, when the protection parameters are modified for several tests, is discussed. The machine protection strategy for the LHC run in 2016 is presented.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY045

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