IPAC2016 - List of Authors (Goddard, B.)

Paper	Title	Page
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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MOPOY058	Removing Known SPS Intensity Limitations for High Luminosity LHC Goals	989
	E.N. Shaposhnikova, T. Argyropoulos, T. Bohl, P. Cruikshank, B. Goddard, T. Kaltenbacher, A. Lasheen, J. Perez Espinos, J. Repond, B. Salvant, C. Vollinger CERN, Geneva, Switzerland
	In preparation of the SPS as an LHC injector its impedance was significantly reduced in 1999 - 2000. A new SPS impedance reduction campaign is planned now for the High Luminosity (HL)-LHC project, which requires bunch intensities twice as high as the nominal one. One of the known intensity limitations is a longitudinal multi-bunch instability with a threshold 3 times below this operational intensity. The instability is presently cured using the 4th harmonic RF system and controlled emittance blow-up, but reaching the HL-LHC parameters cannot be assured without improving the machine impedance. Recently the impedance sources responsible for this instability were identified and implementation of their shielding and damping is foreseen during the next long shutdown (2019 - 2020) in synergy with two other important upgrades: amorphous carbon coating of (part of) the vacuum chamber against the e-cloud effect and rearrangement of the 200 MHz RF system. In this paper the strategy of impedance reduction is presented together with beam intensity achievable after its realisation. The potential effect of other proposals on remaining limitations is also considered.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY058
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MOPOY059	LHC Injectors Upgrade (LIU) Project at CERN	992
	E.N. Shaposhnikova, J. Coupard, H. Damerau, A. Funken, S.S. Gilardoni, B. Goddard, K. Hanke, L. Kobzeva, A.M. Lombardi, D. Manglunki, S. Mataguez, M. Meddahi, B. Mikulec, G. Rumolo, R. Scrivens, M. Vretenar CERN, Geneva, Switzerland
	A massive improvement program of the LHC injector chain is presently being conducted under the LIU project. For the proton chain, this includes the replacement of Linac2 with Linac4 as well as all necessary upgrades to the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS) and Super Proton Synchrotron (SPS), aimed at producing beams with the challenging High Luminosity LHC (HL-LHC) parameters. Regarding the heavy ions, plans to improve the performance of Linac3 and the Low Energy Ion Ring (LEIR) are also pursued under the general LIU program. The full LHC injection chain returned to operation after Long Shutdown 1, with extended beam studies taking place in Run 2. A general project Cost and Schedule Review also took place in March 2015, and several dedicated LIU project reviews were held to address issues awaiting pending decisions. In view of these developments, 2014 and 2015 have been key years to define a number of important aspects of the final LIU path. This paper will describe the reviewed LIU roadmap and revised performance objectives of the main upgrades, including the work status and outlook in terms of the required installation and commissioning stages.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY059
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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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TUPMR048	SPS Injection and Beam Quality for LHC Heavy Ions With 150 ns Kicker Rise Time	1360
	B. Goddard, E. Carlier, L. Ducimetière, G. Kotzian, J.A. Uythoven CERN, Geneva, Switzerland F.M. Velotti EPFL, Lausanne, Switzerland
	As part of the LHC Injectors Upgrade project for LHC heavy ions, the SPS injection kicker system rise time needs reduction below its present 225 ns. One technically challenging option under consideration is the addition of fast Pulse Forming Lines in parallel to the existing Pulse Forming Networks for the 12 kicker magnets MKP-S, targeting a system field rise time of 100 ns. An alternative option is to optimise the system to approach the existing individual magnet field rise time (2-98%) of 150 ns. This would still significantly increase the number of colliding bunches in LHC while minimising the cost and effort of the system upgrade. The observed characteristics of the present system are described, compared to the expected system rise time, together with results of simulations and measurements with 175 and 150 ns injection batch spacing. The expected beam quality at injection into LHC is quantified, with the emittance growth and simulated tail population taking into account expected jitter and synchronisation errors, damper performance and SPS non-linear optics behavior. The outlook for deployment is discussed, with the implications for LHC operation and HL-LHC performance.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR048
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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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TUPMR050	Upgrades to the SPS-to-LHC Transfer Line Beam Stoppers for the LHC High-Luminosity Era	1367
	V. Kain, R. Esposito, M.A. Fraser, B. Goddard, M. Meddahi, A. Perillo Marcone, G.E. Steele, F.M. Velotti CERN, Geneva, Switzerland
	Each of the 3 km long transfer lines between the SPS and the LHC is equipped with two beam stoppers (TEDs), one at the beginning of the line and one close to the LHC injection point, which need to absorb the full transferred beam. The beam stoppers are used for setting up the SPS extractions and transfer lines with beam without having to inject into the LHC. Energy deposition and thermo-mechanical simulations have, however, shown that the TEDs will not be robust enough to safely absorb the high intensity beams foreseen for the high-luminosity LHC era. This paper will summarize the simulation results and limitations for upgrading the beam stoppers. An outline of the hardware upgrade strategy for the TEDs together with modifications to the SPS extraction interlock system to enforce intensity limitations for beam on the beam stoppers will be given.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR050
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TUPMR052	Commissioning Preparation of the AWAKE Proton Beam Line	1374
	J.S. Schmidt, B. Biskup, C. Bracco, B. Goddard, R. Gorbonosov, M. Gourber-Pace, E. Gschwendtner, L.K. Jensen, O.R. Jones, V. Kain, S. Mazzoni, M. Meddahi CERN, Geneva, Switzerland
	The AWAKE experiment at CERN will use a proton bunch with an momentum of 400 GeV/c from the SPS to drive large amplitude wakefields in a plasma. This will require a ~830 m long transfer line from the SPS to the experiment. The prepa- rations for the beam commissioning of the AWAKE proton transfer line are presented in this paper. They include the detailed planning of the commissioning steps, controls and beam instrumentation specifications as well as operational tools, which are developed for the steering and monitoring of the beam line. The installation of the transfer line has been finished and first beam is planned in summer 2016.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR052
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THPMW030	Studies of Impedance-related Improvements of the SPS Injection Kicker System	3611
	M.J. Barnes, A. Adraktas, M.S. Beck, G. Bregliozzi, H.A. Day, L. Ducimetière, J.A. Ferreira Somoza, B. Goddard, T. Kramer, C. Pasquino, G. Rumolo, B. Salvant, L. Sermeus, J.A. Uythoven, L. Vega Cid, W.J.M. Weterings, C. Zannini CERN, Geneva, Switzerland F.M. Velotti EPFL, Lausanne, Switzerland
	The injection kicker system for the SPS consists of sixteen magnets housed in a total of four vacuum tanks. The kicker magnets in one tank have recently limited operation of the SPS with high-intensity beam: this is due to both beam induced heating in the ferrite yoke of the kicker magnets and abnormally high pressure in the vacuum tank. Furthermore, operation with the higher intensity beams needed in the future for HL-LHC is expected to exacerbate these problems. Hence studies of the longitudinal beam coupling impedance of the kicker magnets have been carried out to investigate effective methods to shield the ferrite yoke from the circulating beam. The shielding must not compromise the field quality or high voltage behaviour of the kicker magnets and should not significantly reduce the beam aperture: results of these studies, together with measurements, are presented. In addition results of tests to identify the causes of abnormal outgassing are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW030
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THPMW033	Operational Experience of the Upgraded LHC Injection Kicker Magnets	3623
	M.J. Barnes, A. Adraktas, G. Bregliozzi, S. Calatroni, H.A. Day, L. Ducimetière, B. Goddard, V. Gomes Namora, V. Mertens, B. Salvant, J.A. Uythoven, L. Vega Cid, W.J.M. Weterings, C. Yin Vallgren CERN, Geneva, Switzerland
	During Run 1 of the LHC the injection kicker magnets caused occasional operational delays due to beam induced heating with high bunch intensity and short bunch lengths. In addition, sometimes there were also sporadic issues with microscopic unidentified falling objects, vacuum activity and electrical flashover of the injection kickers. An extensive program of studies was launched and significant upgrades were carried out during long shutdown 1. These upgrades include a new design of a beam screen to both reduce the beam coupling impedance of the kicker magnet, and to significantly reduce the electric field associated with the screen conductors, hence decreasing the probability of electrical breakdown in this region. In addition new cleaning procedures were implemented and equipment adjacent to the injection kickers and various vacuum components were modified. This paper presents operational experience of the injection kicker magnets during Run 2 of the LHC and assesses the effectiveness of the various upgrades.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW033
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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.
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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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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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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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THPOR054	Analysis of the SPS Long Term Orbit Drifts	3914
	F.M. Velotti, C. Bracco, K. Cornelis, L.N. Drøsdal, M.A. Fraser, B. Goddard, V. Kain, M. Meddahi CERN, Geneva, Switzerland E. Gianfelice-Wendt Fermilab, Batavia, Illinois, USA
	The Super Proton Synchrotron (SPS) is the last accelerator in the Large Hadron Collider (LHC) injector chain, and has to deliver the two high-intensity 450 GeV proton beams to the LHC. The transport from SPS to LHC is done through the two Transfer Lines (TL), TI2 and TI8, for Beam 1 (B1) and Beam 2 (B2) respectively. During the first LHC operation period Run 1, a long term drift of the SPS orbit was observed, causing changes in the LHC injection due to the resulting changes in the TL trajectories. This translated into longer LHC turnaround because of the necessity to periodically correct the TL trajectories in order to preserve the beam quality at injection into the LHC. Different sources for the SPS orbit drifts have been investigated: each of them can account only partially for the total orbit drift observed. In this paper, the possible sources of such drift are described, together with the simulated and measured effect they cause. Possible solutions and countermeasures are also discussed.
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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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Paper

Title

Page

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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MOPOY058

Removing Known SPS Intensity Limitations for High Luminosity LHC Goals

989

E.N. Shaposhnikova, T. Argyropoulos, T. Bohl, P. Cruikshank, B. Goddard, T. Kaltenbacher, A. Lasheen, J. Perez Espinos, J. Repond, B. Salvant, C. Vollinger
CERN, Geneva, Switzerland

In preparation of the SPS as an LHC injector its impedance was significantly reduced in 1999 - 2000. A new SPS impedance reduction campaign is planned now for the High Luminosity (HL)-LHC project, which requires bunch intensities twice as high as the nominal one. One of the known intensity limitations is a longitudinal multi-bunch instability with a threshold 3 times below this operational intensity. The instability is presently cured using the 4th harmonic RF system and controlled emittance blow-up, but reaching the HL-LHC parameters cannot be assured without improving the machine impedance. Recently the impedance sources responsible for this instability were identified and implementation of their shielding and damping is foreseen during the next long shutdown (2019 - 2020) in synergy with two other important upgrades: amorphous carbon coating of (part of) the vacuum chamber against the e-cloud effect and rearrangement of the 200 MHz RF system. In this paper the strategy of impedance reduction is presented together with beam intensity achievable after its realisation. The potential effect of other proposals on remaining limitations is also considered.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY058

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MOPOY059

LHC Injectors Upgrade (LIU) Project at CERN

992

E.N. Shaposhnikova, J. Coupard, H. Damerau, A. Funken, S.S. Gilardoni, B. Goddard, K. Hanke, L. Kobzeva, A.M. Lombardi, D. Manglunki, S. Mataguez, M. Meddahi, B. Mikulec, G. Rumolo, R. Scrivens, M. Vretenar
CERN, Geneva, Switzerland

A massive improvement program of the LHC injector chain is presently being conducted under the LIU project. For the proton chain, this includes the replacement of Linac2 with Linac4 as well as all necessary upgrades to the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS) and Super Proton Synchrotron (SPS), aimed at producing beams with the challenging High Luminosity LHC (HL-LHC) parameters. Regarding the heavy ions, plans to improve the performance of Linac3 and the Low Energy Ion Ring (LEIR) are also pursued under the general LIU program. The full LHC injection chain returned to operation after Long Shutdown 1, with extended beam studies taking place in Run 2. A general project Cost and Schedule Review also took place in March 2015, and several dedicated LIU project reviews were held to address issues awaiting pending decisions. In view of these developments, 2014 and 2015 have been key years to define a number of important aspects of the final LIU path. This paper will describe the reviewed LIU roadmap and revised performance objectives of the main upgrades, including the work status and outlook in terms of the required installation and commissioning stages.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY059

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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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TUPMR048

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

1360

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

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

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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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TUPMR050

Upgrades to the SPS-to-LHC Transfer Line Beam Stoppers for the LHC High-Luminosity Era

1367

V. Kain, R. Esposito, M.A. Fraser, B. Goddard, M. Meddahi, A. Perillo Marcone, G.E. Steele, F.M. Velotti
CERN, Geneva, Switzerland

Each of the 3 km long transfer lines between the SPS and the LHC is equipped with two beam stoppers (TEDs), one at the beginning of the line and one close to the LHC injection point, which need to absorb the full transferred beam. The beam stoppers are used for setting up the SPS extractions and transfer lines with beam without having to inject into the LHC. Energy deposition and thermo-mechanical simulations have, however, shown that the TEDs will not be robust enough to safely absorb the high intensity beams foreseen for the high-luminosity LHC era. This paper will summarize the simulation results and limitations for upgrading the beam stoppers. An outline of the hardware upgrade strategy for the TEDs together with modifications to the SPS extraction interlock system to enforce intensity limitations for beam on the beam stoppers will be given.

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TUPMR052

Commissioning Preparation of the AWAKE Proton Beam Line

1374

J.S. Schmidt, B. Biskup, C. Bracco, B. Goddard, R. Gorbonosov, M. Gourber-Pace, E. Gschwendtner, L.K. Jensen, O.R. Jones, V. Kain, S. Mazzoni, M. Meddahi
CERN, Geneva, Switzerland

The AWAKE experiment at CERN will use a proton bunch with an momentum of 400 GeV/c from the SPS to drive large amplitude wakefields in a plasma. This will require a ~830 m long transfer line from the SPS to the experiment. The prepa- rations for the beam commissioning of the AWAKE proton transfer line are presented in this paper. They include the detailed planning of the commissioning steps, controls and beam instrumentation specifications as well as operational tools, which are developed for the steering and monitoring of the beam line. The installation of the transfer line has been finished and first beam is planned in summer 2016.

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THPMW030

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

3611

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

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

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THPMW033

Operational Experience of the Upgraded LHC Injection Kicker Magnets

3623

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

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

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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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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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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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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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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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THPOR054

Analysis of the SPS Long Term Orbit Drifts

3914

F.M. Velotti, C. Bracco, K. Cornelis, L.N. Drøsdal, M.A. Fraser, B. Goddard, V. Kain, M. Meddahi
CERN, Geneva, Switzerland
E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA

The Super Proton Synchrotron (SPS) is the last accelerator in the Large Hadron Collider (LHC) injector chain, and has to deliver the two high-intensity 450 GeV proton beams to the LHC. The transport from SPS to LHC is done through the two Transfer Lines (TL), TI2 and TI8, for Beam 1 (B1) and Beam 2 (B2) respectively. During the first LHC operation period Run 1, a long term drift of the SPS orbit was observed, causing changes in the LHC injection due to the resulting changes in the TL trajectories. This translated into longer LHC turnaround because of the necessity to periodically correct the TL trajectories in order to preserve the beam quality at injection into the LHC. Different sources for the SPS orbit drifts have been investigated: each of them can account only partially for the total orbit drift observed. In this paper, the possible sources of such drift are described, together with the simulated and measured effect they cause. Possible solutions and countermeasures are also discussed.

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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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