IPAC2019 - List of Authors (Wollmann, D.)

Paper	Title	Page
MOPMP036	Machine Protection Experience from Beam Tests with Crab Cavity Prototypes in the CERN SPS	520
	B. Lindstrom, H. Bartosik, T. Bohl, A.C. Butterworth, R. Calaga, L.R. Carver, V. Kain, T.E. Levens, G. Papotti, R. Secondo, J.A. Uythoven, M. Valette, G. Vandoni, J. Wenninger, D. Wollmann, M. Zerlauth CERN, Meyrin, Switzerland
	Funding: Work supported by the High Luminosity LHC project. Crab cavities (CCs) constitute a key component of the High Luminosity LHC (HL-LHC) project. In case of a failure, they can induce significant transverse beam offsets within tens of microseconds, necessitating a fast removal of the circulating beam to avoid damage to accelerator components due to losses from the displaced beam halo. In preparation for the final design to be employed in the LHC, a series of tests were conducted on prototype crab cavities installed in the Super Proton Synchrotron (SPS) at CERN. This paper summarizes the machine protection requirements and observations during the first tests of crab cavities with proton beams in the SPS. In addition, the machine protection implications for future SPS tests and for the use of such equipment in the HL-LHC are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP036
About •	paper received ※ 01 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMP037	Updated High-Energy LHC Design	524
	F. Zimmermann, D. Amorim, S.A. Antipov, S. Arsenyev, M. Benedikt, R. Bruce, M.P. Crouch, S.D. Fartoukh, M. Giovannozzi, B. Goddard, M. Hofer, J. Keintzel, R. Kersevan, V. Mertens, J. Molson, Y. Muttoni, J.A. Osborne, V. Parma, V. Raginel, S. Redaelli, T. Risselada, I. Ruehl, B. Salvant, D. Schoerling, E.N. Shaposhnikova, L.J. Tavian, E. Todesco, R. Tomás, D. Tommasini, F. Valchkova-Georgieva, V. Venturi, D. Wollmann CERN, Geneva, Switzerland J.L. Abelleira, A. Abramov, E. Cruz Alaniz, H. Pikhartova, A. Seryi, L. van Riesen-Haupt JAI, Oxford, United Kingdom A. Apyan ANSL, Yerevan, Armenia J. Barranco García, L. Mether, T. Pieloni, L. Rivkin, C. Tambasco EPFL, Lausanne, Switzerland F. Burkart DESY, Hamburg, Germany Y. Cai, Y.M. Nosochkov SLAC, Menlo Park, California, USA G. Guillermo Cantón CINVESTAV, Mérida, Mexico K. Ohmi, K. Oide, D. Zhou KEK, Ibaraki, Japan
	Funding: This work was supported in part by the European Commission under the HORIZON 2020 project ARIES no.730871, and by the Swiss Accelerator Research and Technology collaboration CHART. We present updated design parameters for a future High-Energy LHC. A more realistic turnaround time has led to a revision of the target peak luminosity, as well as a choice of a larger IP beta function, and longer physics fills. Pushed parameters of the Nb₃Sn superconducting cable together with a modified layout of the 16 T dipole magnets resulted in revised field errors, updated dynamic-aperture simulations, and an associated re-evaluation of injector options. Collimators in the dispersion suppressors help achieve satisfactory cleaning performance. Longitudinal beam parameters ensure beam stability throughout the cycle. Intrabeam scattering rates and Touschek lifetime appear benign.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP037
About •	paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEYYPLM2	The 2018 Heavy-Ion Run of the LHC	2258
	J.M. Jowett, C. Bahamonde Castro, W. Bartmann, C. Bracco, R. Bruce, J.M. Coello de Portugal, J. Dilly, S.D. Fartoukh, E. Fol, N. Fuster-Martínez, A. Garcia-Tabares, M. Hofer, E.B. Holzer, M.A. Jebramcik, J. Keintzel, A. Lechner, E.H. Maclean, L. Malina, T. Medvedeva, A. Mereghetti, T.H.B. Persson, B.Aa. Petersen, S. Redaelli, B. Salvachua, M. Schaumann, C. Schwick, M. Solfaroli, M.L. Spitznagel, H. Timko, R. Tomás, A. Wegscheider, J. Wenninger, D. Wollmann CERN, Meyrin, Switzerland D. Mirarchi The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
	The fourth one-month Pb-Pb collision run brought LHC Run 2 to an end in December 2018. Following the tendency to reduce dependence on the configuration of the preceding proton run, a completely new optics cycle with the strongest ever focussing at the ALICE and LHCb experiments was designed and rapidly implemented, demonstrating the maturity of the collider’s operating modes. Beam-loss monitor thresholds were carefully adjusted to provide optimal protection from the multiple loss mechanisms in heavy-ion operation. A switch from a basic bunch-spacing of 100 ns to 75 ns was made as the beam became available from the injector chain. A new record luminosity, 6 times the original design and close to the operating value proposed for HL-LHC, provided validation of the strategy for mitigating quenches due to bound-free pair production (BFPP) at the interaction points of the ATLAS and CMS experiments. Most of the beam parameters of the HL-LHC Pb-Pb upgrade were attained during this run and the integrated luminosity goals for the first 10 years of LHC operation were substantially exceeded.
	Slides WEYYPLM2 [10.884 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM2
About •	paper received ※ 08 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMP040	Machine Protection Aspects of High-Voltage Flashovers of the LHC Beam Dump Dilution Kickers	2418
	C. Wiesner, W. Bartmann, C. Bracco, M. Calviani, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, S.S. Gilardoni, B. Goddard, V. Gomes Namora, T. Kramer, A. Lechner, N. Magnin, M. Meddahi, A. Perillo-Marcone, T. Polzin, L.C. Richtmann, V. Rizzoglio, V. Senaj, J.A.F. Somoza, D. Wollmann CERN, Meyrin, Switzerland
	The LHC Beam Dump System is required to safely dispose of the energy of the stored beam. In order to reduce the energy density deposited in the beam dump, a dedicated dilution system is installed. On July 14, 2018, during a regular beam dump at 6.5 TeV beam energy, a high-voltage flashover of two vertical dilution kickers was observed, leading to a voltage breakdown and reduced dilution in the vertical plane. It was the first incident of this type since the start of LHC beam operation. In this paper, the flashover event is described and the implications analysed. Circuit simulations of the current in the magnet coil as well as simulations of the resulting beam sweep pattern are presented and compared with the measurements. The criticality of the event is assessed and implications for future failure scenarios are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP040
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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THPRB031	Operational Performance of the Machine Protection Systems of the Large Hadron Collider During Run 2 and Lessons Learnt for the LIU/HL-LHC Era	3875
	M. Zerlauth, A. Antoine, W. Bartmann, C. Bracco, E. Carlier, Z. Charifoulline, R. Denz, B. Goddard, A. Lechner, N. Magnin, C. Martin, R. Mompo, S. Redaelli, I. Romera, B. Salvachua, R. Schmidt, J.A. Uythoven, A.P. Verweij, J. Wenninger, C. Wiesner, D. Wollmann, C. Zamantzas CERN, Geneva, Switzerland
	The Large Hadron Collider (LHC) has successfully completed its second operational run of four years length in December 2018. Operation will be stopped during two years for maintenance and upgrades. To allow for the successful completion of the diverse physics program at 6.5 TeV, the LHC has been routinely operating with stored beam energies close to 300 MJ per beam during high intensity proton runs as well as being frequently reconfigured to allow for special physic runs and important machine developments. No significant damage has incurred to the protected accelerator equipment throughout the run thanks to the excellent performance of the various machine protection systems, however a number of important observations and new failure scenarios have been identified, which were studied experimentally as well as through detailed simulations. In this contribution, we provide an overview of the performance of the machine protection systems throughout Run 2 as well as the important lessons learnt that will impact consolidation actions and the upgrade of the machine protection systems for the LIU/HL-LHC era.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB031
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRB113	Concept of Beam-Related Machine Protection for the Future Circular Collider	4085
	Y.C. Nie, R. Schmidt, J.A. Uythoven, C. Wiesner, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland
	In the Future Circular Collider (FCC) study, a proton-proton circular collider (FCC-hh) is considered with a stored beam energy 20 times higher than that of the LHC. Any uncontrolled release of such energy could potentially result in severe damage to the accelerator components. Machine protection of the FCC-hh is hence very important and challenging. With a machine-protection strategy similar to the LHC, FCC would require up to three turns to dump the beam synchronously after a failure detection. Due to several possible ultrafast failures, which could lead to significant beam losses in a few turns, it is important to further reduce the reaction time of the machine protection system (MPS) for the FCC. Reducing the detection time of a failure by using faster beam monitors, e.g. diamond detectors, can reduce the time between a beam loss and the beam dump request. Communication delay of the interlock system to the beam dumping system can be reduced by using a more direct signal path. More than one beam-free abort gap will shorten the time required for the synchronization between the abort gap and the extraction kicker. Different failure scenarios are classified according to the speed of the failure onset and the subsequent increase of induced beam losses. The critical failure modes, their potential mitigations and impacts on the design of the MPS are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB113
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPTS066	Beam Impact Experiment of 440GeV/p Protons on Superconducting Wires and Tapes in a Cryogenic Environment	4264
	A. Will, A. Bernhard, A.-S. Müller KIT, Karlsruhe, Germany Y. Bastian, B. Bordini, M. Favre, B. Lindstrom, M. Mentink, A. Monteuuis, A. Oslandsbotn, R. Schmidt, A.P. Siemko, K. Stachon, M.P. Vaananen, A.P. Verweij, A. Will, D. Wollmann CERN, Geneva, Switzerland M. Bonura, C. Senatore UNIGE, Geneva, Switzerland A. Usoskin BRUKER HTS GmbH, Alzenau, Germany
	The superconducting magnets used in high energy particle accelerators such as CERN’s LHC can be impacted by the circulating beam in case of specific failure cases. This leads to interaction of the beam particles with the magnet components, like the superconducting coils, directly or via secondary particle showers. The interaction leads to energy deposition in the timescale of microseconds and induces large thermal gradients within the superconductors in the order of 100 K/mm. To investigate the effect on the superconductors, an experiment at CERN’s HiRadMat facility was designed and executed, exposing short samples of Nb-Ti and Nb₃Sn strands as well as YBCO tape in a cryogenic environment to microsecond 440 GeV/p proton beams. The irradiated samples were extracted and are being analyzed for their superconducting properties, such as the critical transport current. This paper describes the experimental setup as well as the first results of the visual inspection of the samples.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS066
About •	paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPTS067	Characterisation of the Radiation Hardness of Cryogenic Bypass Diodes for the HL-LHC Inner Triplet Quadrupole Circuit	4268
	D. Wollmann, C. Cangialosi, C. Cangialosi, F. Cerutti, G. D’Angelo, S. Danzeca, R. Denz, M. Favre, R. Garcia Alia, D. Hagedorn, A. Infantino, G. Kirby, L. Kistrup, T. Koettig, J. Lendaro, B. Lindstrom, A. Monteuuis, F. Rodriguez-Mateos, A.P. Siemko, K. Stachon, A. Tsinganis, M. Valette, A.P. Verweij, A. Will CERN, Geneva, Switzerland A. Bernhard, A.-S. Müller KIT, Karlsruhe, Germany
	Funding: Work supported by the HL-LHC Project. The powering layout of the new HL-LHC Nb₃Sn triplet circuits is the use of cryogenic bypass diodes, where the diodes are located inside an extension to the magnet cryostat, operated in superfluid helium and exposed to radiation. Therefore, the radiation hardness of different type of bypass diodes has been tested at low temperatures in CERN’s CHARM irradiation facility during the operational year 2018. The forward characteristics, the turn on voltage and the reverse blocking voltage of each diode were measured weekly at 4.2 K and 77 K, respectively, as a function of the accumulated radiation dose. The diodes were submitted to a dose close to 12 kGy and a 1 MeV equivalent neutron fluence of 2.2x10¹⁴,n/cm². After the end of the irradiation campaign the annealing behaviour of the diodes was tested by increasing the temperature slowly to 300 K. This paper describes the experimental setup, the measurement procedure and discusses the results of the measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS067
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Machine Protection Experience from Beam Tests with Crab Cavity Prototypes in the CERN SPS

520

B. Lindstrom, H. Bartosik, T. Bohl, A.C. Butterworth, R. Calaga, L.R. Carver, V. Kain, T.E. Levens, G. Papotti, R. Secondo, J.A. Uythoven, M. Valette, G. Vandoni, J. Wenninger, D. Wollmann, M. Zerlauth
CERN, Meyrin, Switzerland

Funding: Work supported by the High Luminosity LHC project.
Crab cavities (CCs) constitute a key component of the High Luminosity LHC (HL-LHC) project. In case of a failure, they can induce significant transverse beam offsets within tens of microseconds, necessitating a fast removal of the circulating beam to avoid damage to accelerator components due to losses from the displaced beam halo. In preparation for the final design to be employed in the LHC, a series of tests were conducted on prototype crab cavities installed in the Super Proton Synchrotron (SPS) at CERN. This paper summarizes the machine protection requirements and observations during the first tests of crab cavities with proton beams in the SPS. In addition, the machine protection implications for future SPS tests and for the use of such equipment in the HL-LHC are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP036

About •

paper received ※ 01 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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MOPMP037

Updated High-Energy LHC Design

524

F. Zimmermann, D. Amorim, S.A. Antipov, S. Arsenyev, M. Benedikt, R. Bruce, M.P. Crouch, S.D. Fartoukh, M. Giovannozzi, B. Goddard, M. Hofer, J. Keintzel, R. Kersevan, V. Mertens, J. Molson, Y. Muttoni, J.A. Osborne, V. Parma, V. Raginel, S. Redaelli, T. Risselada, I. Ruehl, B. Salvant, D. Schoerling, E.N. Shaposhnikova, L.J. Tavian, E. Todesco, R. Tomás, D. Tommasini, F. Valchkova-Georgieva, V. Venturi, D. Wollmann
CERN, Geneva, Switzerland
J.L. Abelleira, A. Abramov, E. Cruz Alaniz, H. Pikhartova, A. Seryi, L. van Riesen-Haupt
JAI, Oxford, United Kingdom
A. Apyan
ANSL, Yerevan, Armenia
J. Barranco García, L. Mether, T. Pieloni, L. Rivkin, C. Tambasco
EPFL, Lausanne, Switzerland
F. Burkart
DESY, Hamburg, Germany
Y. Cai, Y.M. Nosochkov
SLAC, Menlo Park, California, USA
G. Guillermo Cantón
CINVESTAV, Mérida, Mexico
K. Ohmi, K. Oide, D. Zhou
KEK, Ibaraki, Japan

Funding: This work was supported in part by the European Commission under the HORIZON 2020 project ARIES no.730871, and by the Swiss Accelerator Research and Technology collaboration CHART.
We present updated design parameters for a future High-Energy LHC. A more realistic turnaround time has led to a revision of the target peak luminosity, as well as a choice of a larger IP beta function, and longer physics fills. Pushed parameters of the Nb₃Sn superconducting cable together with a modified layout of the 16 T dipole magnets resulted in revised field errors, updated dynamic-aperture simulations, and an associated re-evaluation of injector options. Collimators in the dispersion suppressors help achieve satisfactory cleaning performance. Longitudinal beam parameters ensure beam stability throughout the cycle. Intrabeam scattering rates and Touschek lifetime appear benign.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP037

About •

paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEYYPLM2

The 2018 Heavy-Ion Run of the LHC

2258

J.M. Jowett, C. Bahamonde Castro, W. Bartmann, C. Bracco, R. Bruce, J.M. Coello de Portugal, J. Dilly, S.D. Fartoukh, E. Fol, N. Fuster-Martínez, A. Garcia-Tabares, M. Hofer, E.B. Holzer, M.A. Jebramcik, J. Keintzel, A. Lechner, E.H. Maclean, L. Malina, T. Medvedeva, A. Mereghetti, T.H.B. Persson, B.Aa. Petersen, S. Redaelli, B. Salvachua, M. Schaumann, C. Schwick, M. Solfaroli, M.L. Spitznagel, H. Timko, R. Tomás, A. Wegscheider, J. Wenninger, D. Wollmann
CERN, Meyrin, Switzerland
D. Mirarchi
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom

The fourth one-month Pb-Pb collision run brought LHC Run 2 to an end in December 2018. Following the tendency to reduce dependence on the configuration of the preceding proton run, a completely new optics cycle with the strongest ever focussing at the ALICE and LHCb experiments was designed and rapidly implemented, demonstrating the maturity of the collider’s operating modes. Beam-loss monitor thresholds were carefully adjusted to provide optimal protection from the multiple loss mechanisms in heavy-ion operation. A switch from a basic bunch-spacing of 100 ns to 75 ns was made as the beam became available from the injector chain. A new record luminosity, 6 times the original design and close to the operating value proposed for HL-LHC, provided validation of the strategy for mitigating quenches due to bound-free pair production (BFPP) at the interaction points of the ATLAS and CMS experiments. Most of the beam parameters of the HL-LHC Pb-Pb upgrade were attained during this run and the integrated luminosity goals for the first 10 years of LHC operation were substantially exceeded.

Slides WEYYPLM2 [10.884 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM2

About •

paper received ※ 08 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPMP040

Machine Protection Aspects of High-Voltage Flashovers of the LHC Beam Dump Dilution Kickers

2418

C. Wiesner, W. Bartmann, C. Bracco, M. Calviani, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, S.S. Gilardoni, B. Goddard, V. Gomes Namora, T. Kramer, A. Lechner, N. Magnin, M. Meddahi, A. Perillo-Marcone, T. Polzin, L.C. Richtmann, V. Rizzoglio, V. Senaj, J.A.F. Somoza, D. Wollmann
CERN, Meyrin, Switzerland

The LHC Beam Dump System is required to safely dispose of the energy of the stored beam. In order to reduce the energy density deposited in the beam dump, a dedicated dilution system is installed. On July 14, 2018, during a regular beam dump at 6.5 TeV beam energy, a high-voltage flashover of two vertical dilution kickers was observed, leading to a voltage breakdown and reduced dilution in the vertical plane. It was the first incident of this type since the start of LHC beam operation. In this paper, the flashover event is described and the implications analysed. Circuit simulations of the current in the magnet coil as well as simulations of the resulting beam sweep pattern are presented and compared with the measurements. The criticality of the event is assessed and implications for future failure scenarios are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP040

About •

paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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THPRB031

Operational Performance of the Machine Protection Systems of the Large Hadron Collider During Run 2 and Lessons Learnt for the LIU/HL-LHC Era

3875

M. Zerlauth, A. Antoine, W. Bartmann, C. Bracco, E. Carlier, Z. Charifoulline, R. Denz, B. Goddard, A. Lechner, N. Magnin, C. Martin, R. Mompo, S. Redaelli, I. Romera, B. Salvachua, R. Schmidt, J.A. Uythoven, A.P. Verweij, J. Wenninger, C. Wiesner, D. Wollmann, C. Zamantzas
CERN, Geneva, Switzerland

The Large Hadron Collider (LHC) has successfully completed its second operational run of four years length in December 2018. Operation will be stopped during two years for maintenance and upgrades. To allow for the successful completion of the diverse physics program at 6.5 TeV, the LHC has been routinely operating with stored beam energies close to 300 MJ per beam during high intensity proton runs as well as being frequently reconfigured to allow for special physic runs and important machine developments. No significant damage has incurred to the protected accelerator equipment throughout the run thanks to the excellent performance of the various machine protection systems, however a number of important observations and new failure scenarios have been identified, which were studied experimentally as well as through detailed simulations. In this contribution, we provide an overview of the performance of the machine protection systems throughout Run 2 as well as the important lessons learnt that will impact consolidation actions and the upgrade of the machine protection systems for the LIU/HL-LHC era.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB031

About •

paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB113

Concept of Beam-Related Machine Protection for the Future Circular Collider

4085

Y.C. Nie, R. Schmidt, J.A. Uythoven, C. Wiesner, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland

In the Future Circular Collider (FCC) study, a proton-proton circular collider (FCC-hh) is considered with a stored beam energy 20 times higher than that of the LHC. Any uncontrolled release of such energy could potentially result in severe damage to the accelerator components. Machine protection of the FCC-hh is hence very important and challenging. With a machine-protection strategy similar to the LHC, FCC would require up to three turns to dump the beam synchronously after a failure detection. Due to several possible ultrafast failures, which could lead to significant beam losses in a few turns, it is important to further reduce the reaction time of the machine protection system (MPS) for the FCC. Reducing the detection time of a failure by using faster beam monitors, e.g. diamond detectors, can reduce the time between a beam loss and the beam dump request. Communication delay of the interlock system to the beam dumping system can be reduced by using a more direct signal path. More than one beam-free abort gap will shorten the time required for the synchronization between the abort gap and the extraction kicker. Different failure scenarios are classified according to the speed of the failure onset and the subsequent increase of induced beam losses. The critical failure modes, their potential mitigations and impacts on the design of the MPS are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB113

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS066

Beam Impact Experiment of 440GeV/p Protons on Superconducting Wires and Tapes in a Cryogenic Environment

4264

A. Will, A. Bernhard, A.-S. Müller
KIT, Karlsruhe, Germany
Y. Bastian, B. Bordini, M. Favre, B. Lindstrom, M. Mentink, A. Monteuuis, A. Oslandsbotn, R. Schmidt, A.P. Siemko, K. Stachon, M.P. Vaananen, A.P. Verweij, A. Will, D. Wollmann
CERN, Geneva, Switzerland
M. Bonura, C. Senatore
UNIGE, Geneva, Switzerland
A. Usoskin
BRUKER HTS GmbH, Alzenau, Germany

The superconducting magnets used in high energy particle accelerators such as CERN’s LHC can be impacted by the circulating beam in case of specific failure cases. This leads to interaction of the beam particles with the magnet components, like the superconducting coils, directly or via secondary particle showers. The interaction leads to energy deposition in the timescale of microseconds and induces large thermal gradients within the superconductors in the order of 100 K/mm. To investigate the effect on the superconductors, an experiment at CERN’s HiRadMat facility was designed and executed, exposing short samples of Nb-Ti and Nb₃Sn strands as well as YBCO tape in a cryogenic environment to microsecond 440 GeV/p proton beams. The irradiated samples were extracted and are being analyzed for their superconducting properties, such as the critical transport current. This paper describes the experimental setup as well as the first results of the visual inspection of the samples.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS066

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS067

Characterisation of the Radiation Hardness of Cryogenic Bypass Diodes for the HL-LHC Inner Triplet Quadrupole Circuit

4268

D. Wollmann, C. Cangialosi, C. Cangialosi, F. Cerutti, G. D’Angelo, S. Danzeca, R. Denz, M. Favre, R. Garcia Alia, D. Hagedorn, A. Infantino, G. Kirby, L. Kistrup, T. Koettig, J. Lendaro, B. Lindstrom, A. Monteuuis, F. Rodriguez-Mateos, A.P. Siemko, K. Stachon, A. Tsinganis, M. Valette, A.P. Verweij, A. Will
CERN, Geneva, Switzerland
A. Bernhard, A.-S. Müller
KIT, Karlsruhe, Germany

Funding: Work supported by the HL-LHC Project.
The powering layout of the new HL-LHC Nb₃Sn triplet circuits is the use of cryogenic bypass diodes, where the diodes are located inside an extension to the magnet cryostat, operated in superfluid helium and exposed to radiation. Therefore, the radiation hardness of different type of bypass diodes has been tested at low temperatures in CERN’s CHARM irradiation facility during the operational year 2018. The forward characteristics, the turn on voltage and the reverse blocking voltage of each diode were measured weekly at 4.2 K and 77 K, respectively, as a function of the accumulated radiation dose. The diodes were submitted to a dose close to 12 kGy and a 1 MeV equivalent neutron fluence of 2.2x10¹⁴,n/cm². After the end of the irradiation campaign the annealing behaviour of the diodes was tested by increasing the temperature slowly to 300 K. This paper describes the experimental setup, the measurement procedure and discusses the results of the measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS067

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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