IPAC2014 - List of Authors (Wollmann, D.)

Paper	Title	Page
MOOCB01	Beam-induced Quench Tests of LHC Magnets	52
	M. Sapinski, B. Auchmann, T. Bär, W. Bartmann, M. Bednarek, S. Bozyigit, C. Bracco, R. Bruce, F. Cerutti, V. Chetvertkova, K. Dahlerup-Petersen, B. Dehning, E. Effinger, J. Emery, A. Guerrero, E.B. Holzer, W. Höfle, A. Lechner, A. Priebe, S. Redaelli, B. Salvachua, R. Schmidt, N.V. Shetty, A.P. Siemko, E. Skordis, M. Solfaroli Camillocci, J. Steckert, J.A. Uythoven, D. Valuch, A.P. Verweij, J. Wenninger, D. Wollmann, M. Zerlauth, E.N. del Busto CERN, Geneva, Switzerland
	At the end of the LHC Run1 a 48-hour quench-test campaign took place to investigate the quench levels of superconducting magnets for loss durations from nanoseconds to tens of seconds. The longitudinal losses produced extended from one meter to hundreds of meters and the number of lost protons varied from 10⁸ to 10¹³. The results of these and other, previously conducted quench experiments, allow the quench levels of several types of LHC magnets under various loss conditions to be assessed. The quench levels are expected to limit LHC performance in the case of steady-state losses in the interaction regions and also in the case of fast losses initiated by dust particles all around the ring. It is therefore required to accurately adjust beam loss abort thresholds in order to maximize the operation time. A detailed discussion of these quench test results and a proposal for additional tests after the LHC restart is presented.
	Slides MOOCB01 [2.737 MB]
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MOPRO019	Energy Deposition and Quench Level Calculations for Millisecond and Steady-state Quench Tests of LHC Arc Quadrupoles at 4 TeV	105
	N.V. Shetty, B. Auchmann, V. Chetvertkova, A. Lechner, A. Priebe, M. Sapinski, A.P. Verweij, D. Wollmann CERN, Geneva, Switzerland
	In 2013, beam-induced quench tests with 4 TeV protons were performed to probe the quench level of LHC arc quadrupole magnets at timescales corresponding to millisecond beam losses and steady-state losses. As the energy deposition in magnet coils cannot be measured directly, this study presents corresponding FLUKA simulations as well as estimates of quench levels derived with the QP3 code. Furthermore, beam loss monitor (BLM) signals were simulated and benchmarked against the measurements. Simulated and measured BLM signals are generally found to agree within 30 percent.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO019
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MOPRO043	Handling 1 MW Losses with the LHC Collimation System	174
	B. Salvachua, R. Bruce, F. Carra, M. Cauchi, E.B. Holzer, W. Höfle, D. Jacquet, L. Lari, D. Mirarchi, E. Nebot Del Busto, S. Redaelli, A. Rossi, M. Sapinski, R. Schmidt, G. Valentino, D. Valuch, J. Wenninger, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland M. Cauchi UoM, Msida, Malta L. Lari IFIC, Valencia, Spain
	Funding: Research supported by EU FP7 HiLumi LHC (Grant agree. 284404) The LHC superconducting magnets in the dispersion suppressor of IR7 are the most exposed to beam losses leaking from the betatron collimation system and represent the main limitation for the halo cleaning. In 2013, quench tests were performed at 4 TeV to improve the quench limit estimates, which determine the maximum allowed beam loss rate for a given collimation cleaning. The main goal of the collimation quench test was to try to quench the magnets by increasing losses at the collimators. Losses of up to 1 MW over a few seconds were generated by blowing up the beam, achieving total losses of about 5.8 MJ. These controlled losses exceeded by a factor 2 the collimation design value, and the magnets did not quench.
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MOPME047	Comparison of the Results of a Hydrodynamic Tunneling Experiment with Iterative FLUKA and BIG2 Simulations	479
	F. Burkart, J. Blanco, D. Grenier, R. Schmidt, D. Wollmann CERN, Geneva, Switzerland N.A. Tahir GSI, Darmstadt, Germany
	In 2012, a novel experiment has been performed at the CERN HiRadMat facility to study the impact of a 440 GeV proton beam generated by the Super Proton Synchrotron (SPS), on extended solid copper cylindrical targets. Substantial hydrodynamic tunneling of the protons in the target material has been observed. Iterative FLUKA and BIG2 simulations with the parameters of the actual experiment have been performed. In this paper the results of these simulations will be discussed and compared to the experimental measurements. Furthermore, the implication on the machine protection design for high intensity hadron accelerators as the current LHC and the future High Luminosity LHC will be addressed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME047
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TUPRO015	Update on Predictions for Yearly Integrated Luminosity for HL-LHC based on Expected Machine Availability	1036
	A. Apollonio, M. Jonker, R. Schmidt, B. Todd, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland
	Machine availability is one of the key performance indicators to reach the ambitious goals for integrated luminosity in the post Long Shutdown 1 (LS1) era. Machine availability is even more important for the future High Luminosity LHC (HL-LHC) [1]. In this paper a Monte Carlo approach has been used to predict integrated luminosity as a function of LHC machine availability. The baseline model assumptions such as fault-time distributions and machine failure rate (number of fills with stable beams dumped after a failure / total number of fills with stable beams) were deduced from the observations during LHC operation in 2012. The predictions focus on operation after LS1 and its evolution towards HL-LHC. The extrapolation of relevant parameters impacting on machine availability is outlined and their corresponding impact on fault time distributions is discussed. Results for possible future operational scenarios are presented. Finally, a sensitivity analysis with relevant model parameters like fault time and machine failure rate is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO015
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TUPRO016	Machine Protection Challenges for HL-LHC	1039
	R. Schmidt, T. Bär, J. Wenninger, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland
	LHC operation requires the flawless functioning of the machine protection systems. The energy stored in the beam was progressively increased beyond the 140 MJ range at the end of 2012 at 4 TeV/c. The further increase to 364 MJ expected for 2015 at 6.5 TeV/c should be possible with the existing protection systems. For HL-LHC, additional failure modes are considered. The stored beam energy will increase by another factor of two with respect to nominal and a factor of five more than experienced so far. The maximum beta function will increase. It is planned to install crab cavities in the LHC. With crab cavities, sudden voltage decays within 100 us after e.g. cavity quenches lead to large beam oscillations. Tracking simulations predict trajectory distortions of up to 1.5 σ in the first turn after a sudden drop of the deflecting voltage in a single cavity within 3 turns. The energy of several MJ stored in halo protons that could hit the collimator in case of such events is far above damage level, even if the collimator jaws are made of robust material. In this paper we discuss the challenges for machine protection in the HL-LHC era and possible mitigation strategies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO016
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TUPRO021	Preliminary Study of Risks and Failure Scenarios for the High Luminosity Experiments in HL-LHC	1055
	F. Bouly LPSC, Grenoble Cedex, France R. Alemany-Fernández, H. Burkhardt, D. Wollmann CERN, Geneva, Switzerland B. Yee-Rendón CINVESTAV, Mexico City, Mexico
	For the HL-LHC it is planned to basically double the diameter of the triplet quadruple magnets around the high luminosity insertions of the LHC. The high luminosity experiments ATLAS and CMS would like to keep a small central chamber radius close the interaction point. In the context of collider-experiment studies for the high-luminosity upgrade of the LHC, we present a first study of the possible consequences of these changes for the experimental running conditions based on detailed simulations with tracking. We have started to implement crab cavity failures and discuss first results from these simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO021
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THPME172	Experimental Results from the Characterization of Diamond Particle Detectors with a High Intensity Electron Beam	3671
	F. Burkart, R. Schmidt, O. Stein, D. Wollmann CERN, Geneva, Switzerland E. Griesmayer CIVIDEC Instrumentation, Wien, Austria
	Understanding the sources of ultra-fast failures, with durations of less than 3 LHC turns, is important for a safe operation of the LHC, as only passive protection is possible in these time scales. Diamond particle detectors with bunch-by-bunch resolution and high dynamic range have been successfully used to improve the understanding of some new ultra-fast loss mechanisms discovered in the LHC. To fully exploit their potential, diamond detectors were characterized with a high-intensity electron beam (10⁵ to 1010 electrons per shot). For the first time their efficiency and linearity has been measured in such a wide range of intensities. In this paper the experimental setup will be described and the signals of the different detectors will be discussed. Finally, future applications of these detectors in high-radiation applications will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME172
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THPRI020	Availability Studies for Linac4 and Machine Protection Requirements for Linac4 Commissioning	3807
	A. Apollonio, S. Gabourin, C. Martin, B. Mikulec, B. Puccio, J.L. Sanchez Alvarez, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland
	Linac4 is one of the key elements in the upgrade program of the LHC injector complex at CERN, assuring beams with higher bunch intensities and smaller emittance for the LHC and many other physics experiments on the CERN site. Due to the demand of continuous operation, the expected availability of Linac4 needs to be carefully studied already during its design phase. In this paper an overview of the relevant systems impacting on Linac4 machine availability is given: the various system failure modes are outlined as well as their impact on the total yearly machine downtime. Machine Protection Systems (MPS) play a significant role in reducing the risk associated to each failure mode and are therefore important for reaching the target availability. The Linac4 MPS requirements, with particular focus on the different commissioning phases, are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI020
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THPRI021	Implementation of a Direct Link between the LHC Beam Interlock System and the LHC Beam Dumping System Re-triggering Lines	3810
	S. Gabourin, E. Carlier, R. Denz, N. Magnin, J.A. Uythoven, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland M. Bartholdt, B. Bertsche, V. Vatansever, P. Zeiler Universität Stuttgart, Stuttgart, Germany
	To avoid damage of accelerator equipment due to impacting beam, the controlled removal of the LHC beams from the collider rings towards the dump blocks must be guaranteed at all times. When a beam dump is demanded, the Beam Interlock System communicates this request to the Trigger Synchronisation and Distribution System of the LHC Beam Dumping System. Both systems were built according to high reliability standards. To further reduce the risk of incapability to dump the beams in case of correlated failures in the Trigger Synchronisation and Distribution System, a new direct link from the Beam Interlock System to the re-triggering lines of the LHC Beam Dumping System will be implemented for the start-up with beam in 2015. The link represents a diverse redundancy to the current implementation, which should neither significantly increase the risk for so-called asynchronous beam dumps nor compromise machine availability. This paper describes the implementation choices of this link. Furthermore the results of a reliability analysis to quantify its impact on LHC machine availability are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI021
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THPRI093	CSCM: EXPERIMENTAL AND SIMULATION RESULTS	3988
	S. Rowan, B. Auchmann, K. Brodzinski, Z. Charifoulline, R. Denz, V. Roger, I. Romera, R. Schmidt, A.P. Siemko, J. Steckert, H. Thiesen, A.P. Verweij, G.P. Willering, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland H. Pfeffer Fermilab, Batavia, Illinois, USA
	The copper-stabilizer continuity measurement - or CSCM - was devised to obtain a direct and complete qualification of the continuity in the 13 kA bypass circuits of the LHC, especially in the copper-stabilizer of the busbar joints and the bolted connections in the diode-leads. The circuit under test is brought to ~20 K, a voltage is applied to open the diodes, and the low-inductance circuit is powered with a pre-defined series of current profiles. The profiles are designed to successively increase the thermal load on the busbar joints up to a level that corresponds to worst-case operating conditions at nominal energy. In this way, the circuit is tested for thermal runaways in the joints - the very process that could prove catastrophic if it occurred under nominal conditions with the full circuit energy. Surveillance software and a numerical model were devised to carry out the analysis and ensure complete protection of the circuit from over-heating. A type test of the CSCM was successfully carried out in April 2013 on one main dipole and one main quadrupole circuit of the LHC. This paper describes the analysis procedure, the numerical model, and results of this first type test.
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THPRI094	MadX Tracking Simulations to Determine the Beam loss Distributions for the LHC Quench Tests with ADT Excitation	3991
	V. Chetvertkova, B. Auchmann, T. Bär, W. Höfle, A. Priebe, M. Sapinski, R. Schmidt, A.P. Verweij, D. Wollmann CERN, Geneva, Switzerland
	Quench tests with stored beam were performed in 2013 with one of the LHC main focusing quadrupoles to experimentally verify the quench levels for beam losses in the time scales from a few milliseconds to several seconds. A novel technique combining a 3-corrector orbital bump and transverse-damper kicks was used for inducing the beam losses. MadX tracking simulations were an essential step for determining the spatial and angular beam loss distributions during the experiment. These were then used as input for further energy-deposition and quench-level calculations. In this paper the simulated beam-loss distributions for the respective time scales and experimental parameters are presented. Furthermore the sensitivity of the obtained loss-distributions to the variation of key input parameters, which were measured during the experiment, is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI094
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Paper

Title

Page

Beam-induced Quench Tests of LHC Magnets

52

M. Sapinski, B. Auchmann, T. Bär, W. Bartmann, M. Bednarek, S. Bozyigit, C. Bracco, R. Bruce, F. Cerutti, V. Chetvertkova, K. Dahlerup-Petersen, B. Dehning, E. Effinger, J. Emery, A. Guerrero, E.B. Holzer, W. Höfle, A. Lechner, A. Priebe, S. Redaelli, B. Salvachua, R. Schmidt, N.V. Shetty, A.P. Siemko, E. Skordis, M. Solfaroli Camillocci, J. Steckert, J.A. Uythoven, D. Valuch, A.P. Verweij, J. Wenninger, D. Wollmann, M. Zerlauth, E.N. del Busto
CERN, Geneva, Switzerland

At the end of the LHC Run1 a 48-hour quench-test campaign took place to investigate the quench levels of superconducting magnets for loss durations from nanoseconds to tens of seconds. The longitudinal losses produced extended from one meter to hundreds of meters and the number of lost protons varied from 10⁸ to 10¹³. The results of these and other, previously conducted quench experiments, allow the quench levels of several types of LHC magnets under various loss conditions to be assessed. The quench levels are expected to limit LHC performance in the case of steady-state losses in the interaction regions and also in the case of fast losses initiated by dust particles all around the ring. It is therefore required to accurately adjust beam loss abort thresholds in order to maximize the operation time. A detailed discussion of these quench test results and a proposal for additional tests after the LHC restart is presented.

Slides MOOCB01 [2.737 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOOCB01

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MOPRO019

Energy Deposition and Quench Level Calculations for Millisecond and Steady-state Quench Tests of LHC Arc Quadrupoles at 4 TeV

105

N.V. Shetty, B. Auchmann, V. Chetvertkova, A. Lechner, A. Priebe, M. Sapinski, A.P. Verweij, D. Wollmann
CERN, Geneva, Switzerland

In 2013, beam-induced quench tests with 4 TeV protons were performed to probe the quench level of LHC arc quadrupole magnets at timescales corresponding to millisecond beam losses and steady-state losses. As the energy deposition in magnet coils cannot be measured directly, this study presents corresponding FLUKA simulations as well as estimates of quench levels derived with the QP3 code. Furthermore, beam loss monitor (BLM) signals were simulated and benchmarked against the measurements. Simulated and measured BLM signals are generally found to agree within 30 percent.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO019

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MOPRO043

Handling 1 MW Losses with the LHC Collimation System

174

B. Salvachua, R. Bruce, F. Carra, M. Cauchi, E.B. Holzer, W. Höfle, D. Jacquet, L. Lari, D. Mirarchi, E. Nebot Del Busto, S. Redaelli, A. Rossi, M. Sapinski, R. Schmidt, G. Valentino, D. Valuch, J. Wenninger, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland
M. Cauchi
UoM, Msida, Malta
L. Lari
IFIC, Valencia, Spain

Funding: Research supported by EU FP7 HiLumi LHC (Grant agree. 284404)
The LHC superconducting magnets in the dispersion suppressor of IR7 are the most exposed to beam losses leaking from the betatron collimation system and represent the main limitation for the halo cleaning. In 2013, quench tests were performed at 4 TeV to improve the quench limit estimates, which determine the maximum allowed beam loss rate for a given collimation cleaning. The main goal of the collimation quench test was to try to quench the magnets by increasing losses at the collimators. Losses of up to 1 MW over a few seconds were generated by blowing up the beam, achieving total losses of about 5.8 MJ. These controlled losses exceeded by a factor 2 the collimation design value, and the magnets did not quench.

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MOPME047

Comparison of the Results of a Hydrodynamic Tunneling Experiment with Iterative FLUKA and BIG2 Simulations

479

F. Burkart, J. Blanco, D. Grenier, R. Schmidt, D. Wollmann
CERN, Geneva, Switzerland
N.A. Tahir
GSI, Darmstadt, Germany

In 2012, a novel experiment has been performed at the CERN HiRadMat facility to study the impact of a 440 GeV proton beam generated by the Super Proton Synchrotron (SPS), on extended solid copper cylindrical targets. Substantial hydrodynamic tunneling of the protons in the target material has been observed. Iterative FLUKA and BIG2 simulations with the parameters of the actual experiment have been performed. In this paper the results of these simulations will be discussed and compared to the experimental measurements. Furthermore, the implication on the machine protection design for high intensity hadron accelerators as the current LHC and the future High Luminosity LHC will be addressed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME047

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TUPRO015

Update on Predictions for Yearly Integrated Luminosity for HL-LHC based on Expected Machine Availability

1036

A. Apollonio, M. Jonker, R. Schmidt, B. Todd, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland

Machine availability is one of the key performance indicators to reach the ambitious goals for integrated luminosity in the post Long Shutdown 1 (LS1) era. Machine availability is even more important for the future High Luminosity LHC (HL-LHC) [1]. In this paper a Monte Carlo approach has been used to predict integrated luminosity as a function of LHC machine availability. The baseline model assumptions such as fault-time distributions and machine failure rate (number of fills with stable beams dumped after a failure / total number of fills with stable beams) were deduced from the observations during LHC operation in 2012. The predictions focus on operation after LS1 and its evolution towards HL-LHC. The extrapolation of relevant parameters impacting on machine availability is outlined and their corresponding impact on fault time distributions is discussed. Results for possible future operational scenarios are presented. Finally, a sensitivity analysis with relevant model parameters like fault time and machine failure rate is discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO015

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TUPRO016

Machine Protection Challenges for HL-LHC

1039

R. Schmidt, T. Bär, J. Wenninger, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland

LHC operation requires the flawless functioning of the machine protection systems. The energy stored in the beam was progressively increased beyond the 140 MJ range at the end of 2012 at 4 TeV/c. The further increase to 364 MJ expected for 2015 at 6.5 TeV/c should be possible with the existing protection systems. For HL-LHC, additional failure modes are considered. The stored beam energy will increase by another factor of two with respect to nominal and a factor of five more than experienced so far. The maximum beta function will increase. It is planned to install crab cavities in the LHC. With crab cavities, sudden voltage decays within 100 us after e.g. cavity quenches lead to large beam oscillations. Tracking simulations predict trajectory distortions of up to 1.5 σ in the first turn after a sudden drop of the deflecting voltage in a single cavity within 3 turns. The energy of several MJ stored in halo protons that could hit the collimator in case of such events is far above damage level, even if the collimator jaws are made of robust material. In this paper we discuss the challenges for machine protection in the HL-LHC era and possible mitigation strategies.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO016

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TUPRO021

Preliminary Study of Risks and Failure Scenarios for the High Luminosity Experiments in HL-LHC

1055

F. Bouly
LPSC, Grenoble Cedex, France
R. Alemany-Fernández, H. Burkhardt, D. Wollmann
CERN, Geneva, Switzerland
B. Yee-Rendón
CINVESTAV, Mexico City, Mexico

For the HL-LHC it is planned to basically double the diameter of the triplet quadruple magnets around the high luminosity insertions of the LHC. The high luminosity experiments ATLAS and CMS would like to keep a small central chamber radius close the interaction point. In the context of collider-experiment studies for the high-luminosity upgrade of the LHC, we present a first study of the possible consequences of these changes for the experimental running conditions based on detailed simulations with tracking. We have started to implement crab cavity failures and discuss first results from these simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO021

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THPME172

Experimental Results from the Characterization of Diamond Particle Detectors with a High Intensity Electron Beam

3671

F. Burkart, R. Schmidt, O. Stein, D. Wollmann
CERN, Geneva, Switzerland
E. Griesmayer
CIVIDEC Instrumentation, Wien, Austria

Understanding the sources of ultra-fast failures, with durations of less than 3 LHC turns, is important for a safe operation of the LHC, as only passive protection is possible in these time scales. Diamond particle detectors with bunch-by-bunch resolution and high dynamic range have been successfully used to improve the understanding of some new ultra-fast loss mechanisms discovered in the LHC. To fully exploit their potential, diamond detectors were characterized with a high-intensity electron beam (10⁵ to 1010 electrons per shot). For the first time their efficiency and linearity has been measured in such a wide range of intensities. In this paper the experimental setup will be described and the signals of the different detectors will be discussed. Finally, future applications of these detectors in high-radiation applications will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME172

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THPRI020

Availability Studies for Linac4 and Machine Protection Requirements for Linac4 Commissioning

3807

A. Apollonio, S. Gabourin, C. Martin, B. Mikulec, B. Puccio, J.L. Sanchez Alvarez, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland

Linac4 is one of the key elements in the upgrade program of the LHC injector complex at CERN, assuring beams with higher bunch intensities and smaller emittance for the LHC and many other physics experiments on the CERN site. Due to the demand of continuous operation, the expected availability of Linac4 needs to be carefully studied already during its design phase. In this paper an overview of the relevant systems impacting on Linac4 machine availability is given: the various system failure modes are outlined as well as their impact on the total yearly machine downtime. Machine Protection Systems (MPS) play a significant role in reducing the risk associated to each failure mode and are therefore important for reaching the target availability. The Linac4 MPS requirements, with particular focus on the different commissioning phases, are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI020

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THPRI021

Implementation of a Direct Link between the LHC Beam Interlock System and the LHC Beam Dumping System Re-triggering Lines

3810

S. Gabourin, E. Carlier, R. Denz, N. Magnin, J.A. Uythoven, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland
M. Bartholdt, B. Bertsche, V. Vatansever, P. Zeiler
Universität Stuttgart, Stuttgart, Germany

To avoid damage of accelerator equipment due to impacting beam, the controlled removal of the LHC beams from the collider rings towards the dump blocks must be guaranteed at all times. When a beam dump is demanded, the Beam Interlock System communicates this request to the Trigger Synchronisation and Distribution System of the LHC Beam Dumping System. Both systems were built according to high reliability standards. To further reduce the risk of incapability to dump the beams in case of correlated failures in the Trigger Synchronisation and Distribution System, a new direct link from the Beam Interlock System to the re-triggering lines of the LHC Beam Dumping System will be implemented for the start-up with beam in 2015. The link represents a diverse redundancy to the current implementation, which should neither significantly increase the risk for so-called asynchronous beam dumps nor compromise machine availability. This paper describes the implementation choices of this link. Furthermore the results of a reliability analysis to quantify its impact on LHC machine availability are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI021

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THPRI093

CSCM: EXPERIMENTAL AND SIMULATION RESULTS

3988

S. Rowan, B. Auchmann, K. Brodzinski, Z. Charifoulline, R. Denz, V. Roger, I. Romera, R. Schmidt, A.P. Siemko, J. Steckert, H. Thiesen, A.P. Verweij, G.P. Willering, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland
H. Pfeffer
Fermilab, Batavia, Illinois, USA

The copper-stabilizer continuity measurement - or CSCM - was devised to obtain a direct and complete qualification of the continuity in the 13 kA bypass circuits of the LHC, especially in the copper-stabilizer of the busbar joints and the bolted connections in the diode-leads. The circuit under test is brought to ~20 K, a voltage is applied to open the diodes, and the low-inductance circuit is powered with a pre-defined series of current profiles. The profiles are designed to successively increase the thermal load on the busbar joints up to a level that corresponds to worst-case operating conditions at nominal energy. In this way, the circuit is tested for thermal runaways in the joints - the very process that could prove catastrophic if it occurred under nominal conditions with the full circuit energy. Surveillance software and a numerical model were devised to carry out the analysis and ensure complete protection of the circuit from over-heating. A type test of the CSCM was successfully carried out in April 2013 on one main dipole and one main quadrupole circuit of the LHC. This paper describes the analysis procedure, the numerical model, and results of this first type test.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI093

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THPRI094

MadX Tracking Simulations to Determine the Beam loss Distributions for the LHC Quench Tests with ADT Excitation

3991

V. Chetvertkova, B. Auchmann, T. Bär, W. Höfle, A. Priebe, M. Sapinski, R. Schmidt, A.P. Verweij, D. Wollmann
CERN, Geneva, Switzerland

Quench tests with stored beam were performed in 2013 with one of the LHC main focusing quadrupoles to experimentally verify the quench levels for beam losses in the time scales from a few milliseconds to several seconds. A novel technique combining a 3-corrector orbital bump and transverse-damper kicks was used for inducing the beam losses. MadX tracking simulations were an essential step for determining the spatial and angular beam loss distributions during the experiment. These were then used as input for further energy-deposition and quench-level calculations. In this paper the simulated beam-loss distributions for the respective time scales and experimental parameters are presented. Furthermore the sensitivity of the obtained loss-distributions to the variation of key input parameters, which were measured during the experiment, is discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI094

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