IPAC2016 - List of Authors (Bartmann, W.)

Paper	Title	Page
MOPMR031	Investigation of Injection Losses at the Large Hadron Collider with Diamond Based Particle Detectors	310
	O. Stein, W. Bartmann, F. Burkart, B. Dehning, V. Kain, R. Schmidt, D. Wollmann CERN, Geneva, Switzerland E. Griesmayer CIVIDEC Instrumentation, Wien, Austria
	During the operation of the Large Hadron Collider (LHC) in 2015, increased injection losses were observed. To minimize stress on accelerator components in the injection regions of the LHC and to guarantee an efficient operation these losses needed to be understood and possible mitigation techniques should be studied. Measurements with diamond particle detectors revealed the loss structure with ns-resolution for the first time. Based on these measurements, recaptured beam from the Super Proton Synchrotron (SPS) surrounding the nominal bunch train was identified as the major contributor to the injection loss signals. Methods to reduce the recaptured beam in the SPS were successfully tested and verified with the diamond particle detectors. In this paper the detection and classification of LHC injection losses are described. The methods to reduce these losses and verification measurements are presented and discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR031
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MOPOY007	High Energy Booster Options for a Future Circular Collider at CERN	856
	L.S. Stoel, M.J. Barnes, W. Bartmann, F. Burkart, B. Goddard, W. Herr, T. Kramer, A. Milanese, G. Rumolo, E.N. Shaposhnikova CERN, Geneva, Switzerland
	In case a Future Circular Collider for hadrons (FCC-hh) is constructed at CERN, the tunnels for SPS, LHC and the 100 km collider will be available to house a High Energy Booster (HEB). The different machine options cover a large technology range from an iron-dominated machine in the 100 km tunnel to a superconducting machine in the SPS tunnel. Using a modified LHC as reference, these options are compared with respect to their energy reach, magnet technology and filling time of the collider. Potential issues with beam transfer, reliability and beam stability are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY007
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MOPOY009	ELENA: Installations and Preparations for Commissioning	860
	C. Carli, W. Bartmann, P. Belochitskii, H. Breuker, F. Butin, T. Eriksson, R. Ostojić, S. Pasinelli, G. Tranquille CERN, Geneva, Switzerland W. Oelert Johannes Gutenberg University Mainz, Institut für Physik, Mainz, Germany
	The Extra Low Energy Antiproton ring (ELENA) is a small 30 m circumference synchroton under construction at CERN to further decelerate antiprotons from the Antiproton Decelerator AD from 5.3 MeV to 100 keV. Controlled deceleration in a synchrotron equipped with an electron cooler to reduce emittances in all three planes will allow the existing AD experiments to increase substantially their antiproton capture efficiencies and render new experiments possible. Installation of the machine and lines needed for the commissioning of the ring are ongoing and commissioning is expected to start around mid-2016. The aim is to complete ELENA ring commissioning in November followed by the installation of new electrostatic transfer lines to existing experiments until autumn 2017. Status of ELENA installations and preparations for commissioning will be reported.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY009
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TUPMR046	Sources of Emittance Growth at the CERN PS Booster to PS Transfer	1352
	W. Bartmann, J.L. Abelleira, F. Burkart, B. Goddard, J. Jentzsch, R. Ostojić CERN, Geneva, Switzerland
	The CERN PS Booster (PSB) has four vertically stacked rings. After extraction from each ring, the bunches are recombined in two stages, comprising septum and kicker systems, such that the accumulated bunch train is injected through a single line into the PS. Bunches from the four rings go through a different number of vertical bends, which leads to differences in the betatron and dispersion functions due to edge focussing. The fast pulsed systems at PSB extraction, recombination and PS injection lead to systematic errors of delivery precision at the injection point. These error sources are quantified in terms of emittance growth and particle loss. Mitigations to reduce the overall emittance growth at the PSB to PS transfer within the LHC injectors upgrade are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR046
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TUPMR047	Conceptual Design Considerations for the 50 TeV FCC Beam Dump Insertion	1356
	F. Burkart, M.G. Atanasov, W. Bartmann, B. Goddard, T. Kramer, A. Lechner, A. Sanz Ull, D. Schulte, L.S. Stoel CERN, Geneva, Switzerland D. Barna University of Tokyo, Tokyo, Japan
	Safely extracting and absorbing the 50 TeV proton beams of the FCC-hh collider will be a major challenge. Two extended straight sections (ESS) are dedicated to beam dumping system and collimation. The beam dumping system will fast-extract the beam and transport it to an external absorber, while the collimation system will protect the superconducting accelerator components installed further downstream. The high stored beam energy of about 8.5 GJ per beam means that machine protection considerations will severely constrain the functional design of the ESS and the beam dump line geometry, in addition to dominating the performance specifications of the main sub-systems like kickers and absorber blocks. The general features, including concept choice, optics in the ESS and beam dump line, passive protection devices, layout and integration are described and discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR047
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TUPMR049	Feasibility Study of the PS Injection for 2 GeV LIU Beams with an Upgraded KFA-45 Injection Kicker System Operating in Short Circuit Mode	1363
	T. Kramer, W. Bartmann, J.C.C.M. Borburgh, L. Ducimetière, L.M.C. Feliciano, A. Ferrero Colomo, B. Goddard, L. Sermeus CERN, Geneva, Switzerland
	Under the scope of the LIU project the CERN PS Booster to PS beam transfer will be modified to match the requirements for the future 2 GeV beams. This paper describes the evaluation of the proposed upgrade of the PS injection kicker. Different schemes of an injection for LIU beams into the PS have been outlined in the past already under the aspect of individual transfer kicker rise and fall time performances. Homogeneous rise and fall time requirements in the whole PSB to PS transfer chain have been established which allowed to consider an upgrade option of the present injection kicker system operated in short circuit mode. The challenging pulse quality constraints require an improvement of the flat top and post pulse ripples. Both operation modes, terminated and short circuit mode are analysed and analogue circuit simulations for the present and upgraded system are outlined. Recent measurements on the installed kickers are presented and analysed together with the simulation data. First measurements verifying the performance of upgrade options have been taken during the last end of the year stop. The paper concludes with an upgrade plan and a brief overview of implementation risks.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR049
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THPMB047	Beam Dynamics Studies of the ELENA Electrostatic Transfer Lines in the Presence of Magnetic Stray Fields	3351
	J. Jentzsch, W. Bartmann, M.A. Fraser, R. Ostojić, G. Tranquille CERN, Geneva, Switzerland D. Barna University of Tokyo, Tokyo, Japan
	The ELENA (Extra Low ENergy Antiproton) ring at CERN will further decelerate antiprotons produced at the AD (Antiproton Decelerator) facility from a kinetic energy of 5.3 MeV to 100 keV. The antiprotons will be distributed through a network of electrostatic transfer lines to several experiments, which will replace the existing magnetic transfer lines. The existing experiments and limited space in the AD hall forces the new transfer lines into close proximity to the high-field solenoids used by some experiments to trap the antiprotons. The stray fields from the experimental magnets are known to perturb beam delivery and are a concern for operation at the decreased beam rigidity provided by ELENA. A study was carried out to investigate the influence of stray magnetic fields on the beam, including different ramping periods and operational scenarios. The analytical model of the fields used for simulation will be discussed. Furthermore, trajectory correction algorithms using MADX optic model of the lines have been investigated. The results of these studies as well as specifications of acceptable stray field limits and field attenuation requirements will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB047
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THPMW035	Considerations on an Upgrade Possibility of the LHC Beam Dump Kicker System	3631
	M.A. Fraser, W. Bartmann, C. Bracco, L. Ducimetière, B. Goddard, T. Kramer, V. Senaj CERN, Geneva, Switzerland
	The LHC Beam Dump System (LBDS) is designed to safely dispose the circulating beams over a wide range of energy from 450 GeV up to 7 TeV, where the maximum stored energy is 362 MJ per beam. One of the most critical components of the LBDS are the extraction kickers that must reliably switch on within the 3 us particle-free abort gap. To ensure this functionality, even in the event of a power-cut, the power generator capacitors remain charged and hence the Gate Turn-Off (GTO) switch stack has to hold the full voltage throughout beam operation. The increase of the LHC collision energy to 13 TeV has increased the voltage levels at the GTO stacks and during re-commissioning an increased rate of high-voltage (HV) related issues at the level of the GTO stack was observed. Different solutions have been analysed and an improved GTO stack will be implemented. This paper also outlines the benefit of adding more kicker magnets to improve the voltage hold off issues and to improve the tolerance to missing kickers during extraction.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW035
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THPOR048	Beam Losses at CERNs PS and SPS Measured with Diamond Particle Detectors	3898
	F. Burkart, W. Bartmann, B. Dehning, E. Effinger, M.A. Fraser, B. Goddard, V. Kain, O. Stein CERN, Geneva, Switzerland E. Griesmayer CIVIDEC Instrumentation, Wien, Austria O. Stein University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Diamond particle detectors have been used in the LHC to measure fast particle losses with a nanosecond time resolution. In addition, these detectors were installed in the PS and the SPS. The detectors are mounted close to the extraction septum of the PS (transfer line to SPS) and the SPS (transfer lines TI2 and TI8 to LHC). Mainly, they monitor the losses occurring during the extraction process but the detectors are also able to measure turn-by-turn losses in the accelerators. In addition, detailed studies concerning losses due to ghost bunches were performed. This paper will describe the installed diamond detector setup, discuss the measurement results and possible loss mitigations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR048
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THPOR049	Considerations for the Injection and Extraction Kicker Systems of a 100 TeV Centre-of-Mass FCC-hh Collider	3901
	T. Kramer, M.J. Barnes, W. Bartmann, F. Burkart, L. Ducimetière, B. Goddard, V. Senaj, T. Stadlbauer, D.G. Woog CERN, Geneva, Switzerland D. Barna Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary
	A 100 TeV center-of-mass energy frontier proton collider in a new tunnel of ~100 km circumference is a central part of CERN's Future Circular Colliders (FCC) design study. One of the major challenges for such a machine will be the beam injection and extraction. This paper outlines the recent developments on the injection and extraction kicker system concepts. For injection the system requirements and progress on a new inductive adder design will be presented together with first considerations on the injection kicker magnets. The extraction kicker system comprises the extraction kickers itself as well as the beam dilution kickers, both of which will be part of the FCC beam dump system and will have to reliably abort proton beams with stored energies in the range of 8 Gigajoule. First concepts for the beam dump kicker magnet and generator as well as for the dilution kicker system are described and its feasibility for an abort gap in the 1 μs range is discussed. The potential implications on the overall machine and other key subsystems are outlined, including requirements on (and from) dilution patterns, interlocking, beam intercepting devices and insertion design.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR049
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THPOR051	Beam Based Measurements to Check Integrity of LHC Dump Protection Elements	3908
	C. Bracco, W. Bartmann, M.A. Fraser, B. Goddard, A. Lechner CERN, Geneva, Switzerland
	LHC operation is approaching its nominal operating goals and several upgrades are also being prepared to increase the beam intensity and brightness. In case of an asynchronous beam dump at 6.5 - 7 TeV a non-negligible fraction of the stored energy (360 MJ during nominal operation) will be deposited on the protection elements (TCDQ and TCDS) located downstream of the extraction kickers. These elements are designed to protect the machine aperture from the large amplitude particles resulting from the asynchronous dump. A number of checks and measurements with beam have been worked out to verify the integrity of these elements, after a potentially harmful event, without opening the machine vacuum. Details on measurements and simulations performed to evaluate the validity of the proposed method are presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR051
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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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THPOR055	Characterisation of the SPS Slow-extraction Parameters	3918
	F.M. Velotti, W. Bartmann, T. Bohl, C. Bracco, K. Cornelis, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel CERN, Geneva, Switzerland
	The Super Proton Synchrotron (SPS) is the last accelerator in the Large Hadron Collider (LHC) injector chain but its main users are the fixed-target experiments located in the North Area (NA). The beams, which are among the most intense circulating in the SPS, are extracted to the NA over several thousands of turns by exploiting a third-integer resonant extraction. The unavoidable losses intrinsic to such an extraction makes its optimisation one of the main priorities for operation, to reduce beam induced activation of the machine. The settings of the extraction systems, together with the tune sweep speed and the beam characteristics (momentum spread, emittance, etc.) are the parameters that can be controlled for spill and loss optimisation. In this paper, the contribution of these parameters to the slow-extraction spill quality are investigated through tracking simulations. The simulation model is compared with beam measurements and optimisations suggested.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR055
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Paper

Title

Page

Investigation of Injection Losses at the Large Hadron Collider with Diamond Based Particle Detectors

310

O. Stein, W. Bartmann, F. Burkart, B. Dehning, V. Kain, R. Schmidt, D. Wollmann
CERN, Geneva, Switzerland
E. Griesmayer
CIVIDEC Instrumentation, Wien, Austria

During the operation of the Large Hadron Collider (LHC) in 2015, increased injection losses were observed. To minimize stress on accelerator components in the injection regions of the LHC and to guarantee an efficient operation these losses needed to be understood and possible mitigation techniques should be studied. Measurements with diamond particle detectors revealed the loss structure with ns-resolution for the first time. Based on these measurements, recaptured beam from the Super Proton Synchrotron (SPS) surrounding the nominal bunch train was identified as the major contributor to the injection loss signals. Methods to reduce the recaptured beam in the SPS were successfully tested and verified with the diamond particle detectors. In this paper the detection and classification of LHC injection losses are described. The methods to reduce these losses and verification measurements are presented and discussed.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR031

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MOPOY007

High Energy Booster Options for a Future Circular Collider at CERN

856

L.S. Stoel, M.J. Barnes, W. Bartmann, F. Burkart, B. Goddard, W. Herr, T. Kramer, A. Milanese, G. Rumolo, E.N. Shaposhnikova
CERN, Geneva, Switzerland

In case a Future Circular Collider for hadrons (FCC-hh) is constructed at CERN, the tunnels for SPS, LHC and the 100 km collider will be available to house a High Energy Booster (HEB). The different machine options cover a large technology range from an iron-dominated machine in the 100 km tunnel to a superconducting machine in the SPS tunnel. Using a modified LHC as reference, these options are compared with respect to their energy reach, magnet technology and filling time of the collider. Potential issues with beam transfer, reliability and beam stability are presented.

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MOPOY009

ELENA: Installations and Preparations for Commissioning

860

C. Carli, W. Bartmann, P. Belochitskii, H. Breuker, F. Butin, T. Eriksson, R. Ostojić, S. Pasinelli, G. Tranquille
CERN, Geneva, Switzerland
W. Oelert
Johannes Gutenberg University Mainz, Institut für Physik, Mainz, Germany

The Extra Low Energy Antiproton ring (ELENA) is a small 30 m circumference synchroton under construction at CERN to further decelerate antiprotons from the Antiproton Decelerator AD from 5.3 MeV to 100 keV. Controlled deceleration in a synchrotron equipped with an electron cooler to reduce emittances in all three planes will allow the existing AD experiments to increase substantially their antiproton capture efficiencies and render new experiments possible. Installation of the machine and lines needed for the commissioning of the ring are ongoing and commissioning is expected to start around mid-2016. The aim is to complete ELENA ring commissioning in November followed by the installation of new electrostatic transfer lines to existing experiments until autumn 2017. Status of ELENA installations and preparations for commissioning will be reported.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY009

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TUPMR046

Sources of Emittance Growth at the CERN PS Booster to PS Transfer

1352

W. Bartmann, J.L. Abelleira, F. Burkart, B. Goddard, J. Jentzsch, R. Ostojić
CERN, Geneva, Switzerland

The CERN PS Booster (PSB) has four vertically stacked rings. After extraction from each ring, the bunches are recombined in two stages, comprising septum and kicker systems, such that the accumulated bunch train is injected through a single line into the PS. Bunches from the four rings go through a different number of vertical bends, which leads to differences in the betatron and dispersion functions due to edge focussing. The fast pulsed systems at PSB extraction, recombination and PS injection lead to systematic errors of delivery precision at the injection point. These error sources are quantified in terms of emittance growth and particle loss. Mitigations to reduce the overall emittance growth at the PSB to PS transfer within the LHC injectors upgrade are presented.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR046

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TUPMR047

Conceptual Design Considerations for the 50 TeV FCC Beam Dump Insertion

1356

F. Burkart, M.G. Atanasov, W. Bartmann, B. Goddard, T. Kramer, A. Lechner, A. Sanz Ull, D. Schulte, L.S. Stoel
CERN, Geneva, Switzerland
D. Barna
University of Tokyo, Tokyo, Japan

Safely extracting and absorbing the 50 TeV proton beams of the FCC-hh collider will be a major challenge. Two extended straight sections (ESS) are dedicated to beam dumping system and collimation. The beam dumping system will fast-extract the beam and transport it to an external absorber, while the collimation system will protect the superconducting accelerator components installed further downstream. The high stored beam energy of about 8.5 GJ per beam means that machine protection considerations will severely constrain the functional design of the ESS and the beam dump line geometry, in addition to dominating the performance specifications of the main sub-systems like kickers and absorber blocks. The general features, including concept choice, optics in the ESS and beam dump line, passive protection devices, layout and integration are described and discussed.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR047

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TUPMR049

Feasibility Study of the PS Injection for 2 GeV LIU Beams with an Upgraded KFA-45 Injection Kicker System Operating in Short Circuit Mode

1363

T. Kramer, W. Bartmann, J.C.C.M. Borburgh, L. Ducimetière, L.M.C. Feliciano, A. Ferrero Colomo, B. Goddard, L. Sermeus
CERN, Geneva, Switzerland

Under the scope of the LIU project the CERN PS Booster to PS beam transfer will be modified to match the requirements for the future 2 GeV beams. This paper describes the evaluation of the proposed upgrade of the PS injection kicker. Different schemes of an injection for LIU beams into the PS have been outlined in the past already under the aspect of individual transfer kicker rise and fall time performances. Homogeneous rise and fall time requirements in the whole PSB to PS transfer chain have been established which allowed to consider an upgrade option of the present injection kicker system operated in short circuit mode. The challenging pulse quality constraints require an improvement of the flat top and post pulse ripples. Both operation modes, terminated and short circuit mode are analysed and analogue circuit simulations for the present and upgraded system are outlined. Recent measurements on the installed kickers are presented and analysed together with the simulation data. First measurements verifying the performance of upgrade options have been taken during the last end of the year stop. The paper concludes with an upgrade plan and a brief overview of implementation risks.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR049

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THPMB047

Beam Dynamics Studies of the ELENA Electrostatic Transfer Lines in the Presence of Magnetic Stray Fields

3351

J. Jentzsch, W. Bartmann, M.A. Fraser, R. Ostojić, G. Tranquille
CERN, Geneva, Switzerland
D. Barna
University of Tokyo, Tokyo, Japan

The ELENA (Extra Low ENergy Antiproton) ring at CERN will further decelerate antiprotons produced at the AD (Antiproton Decelerator) facility from a kinetic energy of 5.3 MeV to 100 keV. The antiprotons will be distributed through a network of electrostatic transfer lines to several experiments, which will replace the existing magnetic transfer lines. The existing experiments and limited space in the AD hall forces the new transfer lines into close proximity to the high-field solenoids used by some experiments to trap the antiprotons. The stray fields from the experimental magnets are known to perturb beam delivery and are a concern for operation at the decreased beam rigidity provided by ELENA. A study was carried out to investigate the influence of stray magnetic fields on the beam, including different ramping periods and operational scenarios. The analytical model of the fields used for simulation will be discussed. Furthermore, trajectory correction algorithms using MADX optic model of the lines have been investigated. The results of these studies as well as specifications of acceptable stray field limits and field attenuation requirements will be presented.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB047

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THPMW035

Considerations on an Upgrade Possibility of the LHC Beam Dump Kicker System

3631

M.A. Fraser, W. Bartmann, C. Bracco, L. Ducimetière, B. Goddard, T. Kramer, V. Senaj
CERN, Geneva, Switzerland

The LHC Beam Dump System (LBDS) is designed to safely dispose the circulating beams over a wide range of energy from 450 GeV up to 7 TeV, where the maximum stored energy is 362 MJ per beam. One of the most critical components of the LBDS are the extraction kickers that must reliably switch on within the 3 us particle-free abort gap. To ensure this functionality, even in the event of a power-cut, the power generator capacitors remain charged and hence the Gate Turn-Off (GTO) switch stack has to hold the full voltage throughout beam operation. The increase of the LHC collision energy to 13 TeV has increased the voltage levels at the GTO stacks and during re-commissioning an increased rate of high-voltage (HV) related issues at the level of the GTO stack was observed. Different solutions have been analysed and an improved GTO stack will be implemented. This paper also outlines the benefit of adding more kicker magnets to improve the voltage hold off issues and to improve the tolerance to missing kickers during extraction.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW035

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THPOR048

Beam Losses at CERNs PS and SPS Measured with Diamond Particle Detectors

3898

F. Burkart, W. Bartmann, B. Dehning, E. Effinger, M.A. Fraser, B. Goddard, V. Kain, O. Stein
CERN, Geneva, Switzerland
E. Griesmayer
CIVIDEC Instrumentation, Wien, Austria
O. Stein
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Diamond particle detectors have been used in the LHC to measure fast particle losses with a nanosecond time resolution. In addition, these detectors were installed in the PS and the SPS. The detectors are mounted close to the extraction septum of the PS (transfer line to SPS) and the SPS (transfer lines TI2 and TI8 to LHC). Mainly, they monitor the losses occurring during the extraction process but the detectors are also able to measure turn-by-turn losses in the accelerators. In addition, detailed studies concerning losses due to ghost bunches were performed. This paper will describe the installed diamond detector setup, discuss the measurement results and possible loss mitigations.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR048

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THPOR049

Considerations for the Injection and Extraction Kicker Systems of a 100 TeV Centre-of-Mass FCC-hh Collider

3901

T. Kramer, M.J. Barnes, W. Bartmann, F. Burkart, L. Ducimetière, B. Goddard, V. Senaj, T. Stadlbauer, D.G. Woog
CERN, Geneva, Switzerland
D. Barna
Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Budapest, Hungary

A 100 TeV center-of-mass energy frontier proton collider in a new tunnel of ~100 km circumference is a central part of CERN's Future Circular Colliders (FCC) design study. One of the major challenges for such a machine will be the beam injection and extraction. This paper outlines the recent developments on the injection and extraction kicker system concepts. For injection the system requirements and progress on a new inductive adder design will be presented together with first considerations on the injection kicker magnets. The extraction kicker system comprises the extraction kickers itself as well as the beam dilution kickers, both of which will be part of the FCC beam dump system and will have to reliably abort proton beams with stored energies in the range of 8 Gigajoule. First concepts for the beam dump kicker magnet and generator as well as for the dilution kicker system are described and its feasibility for an abort gap in the 1 μs range is discussed. The potential implications on the overall machine and other key subsystems are outlined, including requirements on (and from) dilution patterns, interlocking, beam intercepting devices and insertion design.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR049

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THPOR051

Beam Based Measurements to Check Integrity of LHC Dump Protection Elements

3908

C. Bracco, W. Bartmann, M.A. Fraser, B. Goddard, A. Lechner
CERN, Geneva, Switzerland

LHC operation is approaching its nominal operating goals and several upgrades are also being prepared to increase the beam intensity and brightness. In case of an asynchronous beam dump at 6.5 - 7 TeV a non-negligible fraction of the stored energy (360 MJ during nominal operation) will be deposited on the protection elements (TCDQ and TCDS) located downstream of the extraction kickers. These elements are designed to protect the machine aperture from the large amplitude particles resulting from the asynchronous dump. A number of checks and measurements with beam have been worked out to verify the integrity of these elements, after a potentially harmful event, without opening the machine vacuum. Details on measurements and simulations performed to evaluate the validity of the proposed method are presented in this paper.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR051

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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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THPOR055

Characterisation of the SPS Slow-extraction Parameters

3918

F.M. Velotti, W. Bartmann, T. Bohl, C. Bracco, K. Cornelis, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel
CERN, Geneva, Switzerland

The Super Proton Synchrotron (SPS) is the last accelerator in the Large Hadron Collider (LHC) injector chain but its main users are the fixed-target experiments located in the North Area (NA). The beams, which are among the most intense circulating in the SPS, are extracted to the NA over several thousands of turns by exploiting a third-integer resonant extraction. The unavoidable losses intrinsic to such an extraction makes its optimisation one of the main priorities for operation, to reduce beam induced activation of the machine. The settings of the extraction systems, together with the tune sweep speed and the beam characteristics (momentum spread, emittance, etc.) are the parameters that can be controlled for spill and loss optimisation. In this paper, the contribution of these parameters to the slow-extraction spill quality are investigated through tracking simulations. The simulation model is compared with beam measurements and optimisations suggested.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR055

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