IPAC2016 - List of Keywords (hadron)

Paper	Title	Other Keywords	Page
MOZA01	Simulated Beam-beam Limits for Circular Lepton and Hadron Colliders	simulation, collider, luminosity, lepton	27
	K. Ohmi KEK, Ibaraki, Japan
	The beam-beam limit is one of the most important collider parameters. For lepton colliders the empirical tune shift limits are higher than for hadron colliders, which has been attributed to strong radiation damping. The beam-beam limit in hadron colliders, like the LHC, can be affected by noise. For future higher-energy colliders, like FCC-hh or SppC, the limit can be higher or lower, in the presence of still rather weak synchrotron radiation. For circular lepton colliders, like DAΦNE, SuperKEKB, FCC-ee or CepC, the effect of large Piwinski angle, and crab waist, as well as the dependence of the beam-beam limit on the number of interaction points are important questions. This presentation reviews the state of the art in weak-strong, quasi-strong-strong and strong-strong beam-beam simulations and reports the various dependencies of the simulated beam-beam limit on the aforementioned parameters.
	Slides MOZA01 [4.453 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOZA01
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MOPMR018	Beam Position Monitor for Circular Proton Accelerators	controls, instrumentation, interface, closed-orbit	267
	M. Žnidarčič, E. Janezic I-Tech, Solkan, Slovenia K. Lang GSI, Darmstadt, Germany
	Position monitoring, tune calculation and subsequent optimization of hadron circular accelerators requires specific instrumentation. Libera Hadron is the newly developed instrument intended for data acquisition and post processing of signals from shoe-box or capacitive type pickups. Development, initial measurements and verification of the instrument performance were conducted in the Instrumentation Technologies' laboratories, followed by the characterization measurements of the unit carried out at Facility for Anti-proton and Ion Research (FAIR) facility. This article discusses the new BPM electronics concept, the tests performed and the performance obtained.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR018
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MOPOY007	High Energy Booster Options for a Future Circular Collider at CERN	injection, booster, collider, extraction	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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TUXA01	Status and Future Upgrade of J-PARC Accelerators	linac, operation, injection, extraction	999
	M. Kinsho JAEA/J-PARC, Tokai-mura, Japan
	The linac energy reached to 400 MeV as a design value and also a beam current was upgraded to 50 mA by replacing a new ion source. At the 3 GeV synchrotron, a high power beam of 8.41x10¹³ protons per pulse was demonstrated, which was equivalent to 1 MW when the repetition would be 25 Hz. At the main ring, beam loss was reduced by suppression of transverse instabilities and so on. The beam power for both the neutrino experiment and hadron experimental facility is increasing to reduce beam loss. J-PARC accelerators each have their own upgrade plan to increase beam power. The progress and future plan of J-PARC accelerators are reported in this paper.
	Slides TUXA01 [11.427 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUXA01
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TUPMB042	Sweet Spot Designs for Interaction Region Septum Magnets	dipole, quadrupole, shielding, electron	1196
	B. Parker BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. A fundamental consideration in designing a high energy collider Interaction Region with electron beams is to avoid production of excessive experimental detector background due to synchrotron radiation. Circumventing such radiation is especially problematic with colliding beams having quite different magnetic rigidities as occurs in both electron-hadron and asymmetric-momentum electron colliders where one must shield an incoming electron beam from the strong magnetic fields needed to focus the other beam. After reviewing some magnetic configurations used to date, we introduce a new 'sweet spot' coil concept that was invented for the eRHIC project proposed at BNL. Sweet spot coils have conductors arranged so that there is an open, low field strength path through the main high field superconducting coil structure. Sweet spot configurations tend to be more efficient than other active and passive shielding solutions. Dipole and quadrupole sweet spot magnet designs examples are presented in this paper along with ongoing R&D to implement and test these concepts.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB042
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TUPMW007	Impact of Long Range Beam-Beam Effects on Intensity and Luminosity Lifetimes from the 2015 LHC Run	luminosity, emittance, experiment, dynamic-aperture	1422
	M.P. Crouch, R.B. Appleby UMAN, Manchester, United Kingdom D. Banfi, C. Tambasco EPFL, Lausanne, Switzerland J. Barranco, R. Bruce, X. Buffat, T. Pieloni, M. Pojer, B. Salvachua, G. Trad CERN, Geneva, Switzerland B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Research supported by the High Luminosity LHC project Luminosity is one of the key parameters that determines the performance of colliding beams in the Large Hadron Collider (LHC). Luminosity can therefore be used to quantify the impact of beam-beam interactions on the beam lifetimes and emittances. The High Luminosity Large Hadron Collider (HL-LHC) project aims to reach higher luminosities, approximately a factor of 7 larger than the nominal LHC at peak luminosity without crab cavities. Higher luminosities are achieved by increasing the bunch populations and reducing the transverse beam sizes. This results in stronger beam-beam effects. Here the LHC luminosity and beam intensity decay rates are analysed as a function of reducing beam separation with the aim of characterising the impact of beam-beam effects on the luminosity and beam lifetime. The analysis and results are discussed with possible application to the HL-LHC upgrade.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW007
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TUPMW026	Feed-Forward Corrections for Tune and Chromaticity Injection Decay During 2015 LHC Operation	injection, operation, collider, octupole	1489
	M. Solfaroli Camillocci, M. Juchno, M. Lamont, M. Schaumann, E. Todesco, J. Wenninger CERN, Geneva, Switzerland
	After two years of shutdown, the Large Hadron Collider (LHC) has been operated in 2015 at 6.5 TeV, close to its designed energy. When the current is stable at low field, the harmonic components of the main circuits are subject to a dynamic variation induced by current redistribution on the superconducting cables. The Field Description of the LHC (FiDel) foresaw an increase of the decay at injection of tune (quadrupolar components) and chromaticity (sextupolar components) of about 50% with respect to LHC Run1 due to the higher operational current. This paper discusses the beam-based measurements of the decay during the injection plateau and the implementation and accuracy of the feed-forward corrections as present in 2015. Moreover, the observed tune shift proportional to the circulating beam intensity and it's foreseen feed-forward correction are covered.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW026
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TUPMW037	Luminosity Targets for FCC-hh	luminosity, collider, proton, detector	1523
	F. Zimmermann, M. Benedikt, X. Buffat, D. Schulte CERN, Geneva, Switzerland
	Funding: Supported by the European Commission under the Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and under the HORIZON 2020 project EuroCirCol, grant agreement 654305. We discuss the choice of target values for the peak and integrated luminosity of a future high-energy frontier circular hadron collider (FCC-hh). We review the arguments on the physics reach of a hadron collider. Next we show that accelerator constraints will limit the beam current and the turnaround time. Taking these limits into account, we derive an expression for the ultimate integrated luminosity per year, depending on a possible pile-up limit imposed by the physics experiments. We finally benchmark our result against the planned two phases of FCC-hh.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW037
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WEPMW027	The ERL-based Design of Electron-Hadron Collider eRHIC	electron, linac, luminosity, proton	2482
	V. Ptitsyn, E.C. Aschenauer, I. Ben-Zvi, J.S. Berg, M. Blaskiewicz, S.J. Brooks, K.A. Brown, J.C. Brutus, O.V. Chubar, A.V. Fedotov, D.M. Gassner, H. Hahn, Y. Hao, A. Hershcovitch, H. Huang, W.A. Jackson, Y.C. Jing, R.F. Lambiase, V. Litvinenko, C. Liu, Y. Luo, G.J. Mahler, B. Martin, G.T. McIntyre, W. Meng, F. Méot, T.A. Miller, M.G. Minty, B. Parker, I. Pinayev, V.H. Ranjbar, T. Roser, J. Skaritka, R. Than, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, E. Wang, G. Wang, H. Witte, Q. Wu, C. Xu, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Recent developments of the ERL-based design of future high luminosity electron-hadron collider eRHIC focused on balancing technological risks present in the design versus the design cost. As a result a lower risk design has been adopted at moderate cost increase. The modifications include a change of the main linac RF frequency, reduced number of SRF cavity types and modified electron spin transport using a spin rotator. A luminosity-staged approach is being explored with a Nominal design (L ~ 10³³ cm^-2 s^-1) that employs reduced electron current and could possibly be based on classical electron cooling, and then with the Ultimate design (L > 10³⁴ cm^-2 s^-1) that uses higher electron current and an innovative cooling technique (CeC). The paper describes the recent design modifications, and presents the full status of the eRHIC ERL-based design.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW027
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WEPMW036	MERLIN Cleaning Studies with Advanced Collimator Materials for HL-LHC	scattering, collimation, simulation, proton	2514
	A. Valloni, R. Bruce, A. Mereghetti, E. Quaranta, S. Redaelli CERN, Geneva, Switzerland R.B. Appleby UMAN, Manchester, United Kingdom J. Molson LAL, Orsay, France H. Rafique University of Huddersfield, Huddersfield, United Kingdom
	The challenges of the High-Luminosity upgrade of the Large Hadron Collider require improving the beam collimation system. An intense R&D program has started at CERN to explore novel materials for new collimator jaws to improve robustness and reduce impedance. Particle tracking simulations of collimation efficiency are performed using the code MERLIN which has been extended to include new materials based on composites. After presenting two different implementations of composite materials tested in MERLIN, we present simulation studies with the aim of studying the effect of the advanced collimators on the LHC beam cleaning.
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WEPOY056	Beam-beam Simulations with Realistic Crab Crossing for the eRhic Ring-Ring Electron Beam	electron, proton, cavity, luminosity	3123
	C. Montag BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The 15mrad beam crossing angle in the eRHIC ring-ring interaction region requires crab crossing of the 250GeV proton beam to restore the luminosity. Since the product of the RF voltage and the RF frequency of the crab cavities is constant for a given crossing angle, higher frequencies are preferred in order to limit the require voltage. However, the 20cm RMS proton bunch length provides an upper limit of the useable frequencies due to the significant curvature of the RF waveform over this bunch length. To study the effectof realistic crab cavities with a finite wavelength on electron beam-beamdynamics and to determine the potential need for higher harmonic crab cavities to linearize the kick a simulation code has been developed.
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WEPOY058	Design of the 2015 Erhic Ring-Ring Interaction Region	electron, proton, neutron, quadrupole	3129
	C. Montag, B. Parker BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The 2015 ring-ring design study of the electron-ion collider eRHIC aims at an e-p luminosity around 10³³ cm^-2 sec^-1 over a center-of-mass energy range from 32 to 141 GeV, while at the same time providing the required detector geometry and acceptance for the proposed physics program. The latest interaction region design will be presented.
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THPMB042	Residual Orbit Correction Studies for the FCC-hh	quadrupole, dipole, alignment, photon	3332
	D. Boutin, B. Dalena CEA/IRFU, Gif-sur-Yvette, France A. Chancé, J. Payet CEA/DSM/IRFU, France B.J. Holzer, R. Martin, D. Schulte CERN, Geneva, Switzerland
	The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the three options considered for the next genera-tion accelerator in high-energy physics as recommended by the European Strategy Group []. Preliminary studies have started to estimate the design parameters of FCC-hh. One of these studies is the calculation of the residual orbit in the arcs of the collider. This is very important for the evaluation of the alignment tolerances of the quadru-poles used in the arcs, the dimensioning of the correctors and of the beam screen. Moreover it has an impact on the dynamic aperture of the ring and the field tolerances of the arc multipoles. To perform the simulations, the beam transport code MADX has been used. Systematic studies of the residual orbit and of the correctors' strength de-pendence on the magnets misalignment or field errors are presented and discussed. [] A. Ball et al., EDMS-0134202.
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THPMB044	Limitations on Optics Measurements in the LHC	optics, dipole, injection, luminosity	3339
	P.K. Skowroński, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, A. Langner, E.H. Maclean, L. Malina, M. McAteer, T. Persson, R. Tomás CERN, Geneva, Switzerland A. Langner University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany L. Malina University of Oslo, Oslo, Norway
	In preparation of the optics commissioning at an energy of 6.5 TeV, many improvements have been done to cope with the expected reduced signal to noise ratio due to lowered bunch intensities imposed by machine protection considerations. This included, among others, an increase of the flat top duration of the AC dipole excitations, which allowed to use more turn-by-turn data for the analysis. The longer data acquisition revealed slow drifts of the optics, which limited the increased measurement precision. Furthermore, we will present how orbit drifts influenced dispersion measurements and, as a consequence, posed another limitation for the optics correction. In this paper we will discuss the implications of these observations for the measurement and correction of the optics.
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THPOY045	Commissioning of the Machine Protection Systems of the Large Hadron Collider Following its First Long Shutdown	operation, dipole, injection, beam-losses	4203
	D. Wollmann, R. Schmidt, J.A. Uythoven, J. Wenninger, M. Zerlauth CERN, Geneva, Switzerland
	During the first long shutdown of the Large Hadron Collider (LHC) extending for more than 18 months, most Machine Protection Systems (MPS) have undergone significant changes, and upgrades. A full re-commissioning of the MPS was performed at the end of the shutdown and during the LHC beam commissioning in 2015. To verify the correct functioning of all protection-relevant systems with beam, a step-wise intensity ramp-up was performed, reaching at the end of 2015 a record stored beam energy of ~280 MJ per beam, nearly 80% of the value in the design report. This contribution summarizes the results of the MPS commissioning, the intensity ramp-up and the continuous follow-up during operation, focusing mainly on near misses and false triggers and their proposed mitigations. A strategy to minimize risks during machine development periods for future operation of the LHC, when the protection parameters are modified for several tests, is discussed. The machine protection strategy for the LHC run in 2016 is presented.
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Paper

Title

Other Keywords

Page

MOZA01

Simulated Beam-beam Limits for Circular Lepton and Hadron Colliders

simulation, collider, luminosity, lepton

27

K. Ohmi
KEK, Ibaraki, Japan

The beam-beam limit is one of the most important collider parameters. For lepton colliders the empirical tune shift limits are higher than for hadron colliders, which has been attributed to strong radiation damping. The beam-beam limit in hadron colliders, like the LHC, can be affected by noise. For future higher-energy colliders, like FCC-hh or SppC, the limit can be higher or lower, in the presence of still rather weak synchrotron radiation. For circular lepton colliders, like DAΦNE, SuperKEKB, FCC-ee or CepC, the effect of large Piwinski angle, and crab waist, as well as the dependence of the beam-beam limit on the number of interaction points are important questions. This presentation reviews the state of the art in weak-strong, quasi-strong-strong and strong-strong beam-beam simulations and reports the various dependencies of the simulated beam-beam limit on the aforementioned parameters.

Slides MOZA01 [4.453 MB]

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MOPMR018

Beam Position Monitor for Circular Proton Accelerators

controls, instrumentation, interface, closed-orbit

267

M. Žnidarčič, E. Janezic
I-Tech, Solkan, Slovenia
K. Lang
GSI, Darmstadt, Germany

Position monitoring, tune calculation and subsequent optimization of hadron circular accelerators requires specific instrumentation. Libera Hadron is the newly developed instrument intended for data acquisition and post processing of signals from shoe-box or capacitive type pickups. Development, initial measurements and verification of the instrument performance were conducted in the Instrumentation Technologies' laboratories, followed by the characterization measurements of the unit carried out at Facility for Anti-proton and Ion Research (FAIR) facility. This article discusses the new BPM electronics concept, the tests performed and the performance obtained.

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MOPOY007

High Energy Booster Options for a Future Circular Collider at CERN

injection, booster, collider, extraction

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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TUXA01

Status and Future Upgrade of J-PARC Accelerators

linac, operation, injection, extraction

999

M. Kinsho
JAEA/J-PARC, Tokai-mura, Japan

The linac energy reached to 400 MeV as a design value and also a beam current was upgraded to 50 mA by replacing a new ion source. At the 3 GeV synchrotron, a high power beam of 8.41x10¹³ protons per pulse was demonstrated, which was equivalent to 1 MW when the repetition would be 25 Hz. At the main ring, beam loss was reduced by suppression of transverse instabilities and so on. The beam power for both the neutrino experiment and hadron experimental facility is increasing to reduce beam loss. J-PARC accelerators each have their own upgrade plan to increase beam power. The progress and future plan of J-PARC accelerators are reported in this paper.

Slides TUXA01 [11.427 MB]

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TUPMB042

Sweet Spot Designs for Interaction Region Septum Magnets

dipole, quadrupole, shielding, electron

1196

B. Parker
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A fundamental consideration in designing a high energy collider Interaction Region with electron beams is to avoid production of excessive experimental detector background due to synchrotron radiation. Circumventing such radiation is especially problematic with colliding beams having quite different magnetic rigidities as occurs in both electron-hadron and asymmetric-momentum electron colliders where one must shield an incoming electron beam from the strong magnetic fields needed to focus the other beam. After reviewing some magnetic configurations used to date, we introduce a new 'sweet spot' coil concept that was invented for the eRHIC project proposed at BNL. Sweet spot coils have conductors arranged so that there is an open, low field strength path through the main high field superconducting coil structure. Sweet spot configurations tend to be more efficient than other active and passive shielding solutions. Dipole and quadrupole sweet spot magnet designs examples are presented in this paper along with ongoing R&D to implement and test these concepts.

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TUPMW007

Impact of Long Range Beam-Beam Effects on Intensity and Luminosity Lifetimes from the 2015 LHC Run

luminosity, emittance, experiment, dynamic-aperture

1422

M.P. Crouch, R.B. Appleby
UMAN, Manchester, United Kingdom
D. Banfi, C. Tambasco
EPFL, Lausanne, Switzerland
J. Barranco, R. Bruce, X. Buffat, T. Pieloni, M. Pojer, B. Salvachua, G. Trad
CERN, Geneva, Switzerland
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Research supported by the High Luminosity LHC project
Luminosity is one of the key parameters that determines the performance of colliding beams in the Large Hadron Collider (LHC). Luminosity can therefore be used to quantify the impact of beam-beam interactions on the beam lifetimes and emittances. The High Luminosity Large Hadron Collider (HL-LHC) project aims to reach higher luminosities, approximately a factor of 7 larger than the nominal LHC at peak luminosity without crab cavities. Higher luminosities are achieved by increasing the bunch populations and reducing the transverse beam sizes. This results in stronger beam-beam effects. Here the LHC luminosity and beam intensity decay rates are analysed as a function of reducing beam separation with the aim of characterising the impact of beam-beam effects on the luminosity and beam lifetime. The analysis and results are discussed with possible application to the HL-LHC upgrade.

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TUPMW026

Feed-Forward Corrections for Tune and Chromaticity Injection Decay During 2015 LHC Operation

injection, operation, collider, octupole

1489

M. Solfaroli Camillocci, M. Juchno, M. Lamont, M. Schaumann, E. Todesco, J. Wenninger
CERN, Geneva, Switzerland

After two years of shutdown, the Large Hadron Collider (LHC) has been operated in 2015 at 6.5 TeV, close to its designed energy. When the current is stable at low field, the harmonic components of the main circuits are subject to a dynamic variation induced by current redistribution on the superconducting cables. The Field Description of the LHC (FiDel) foresaw an increase of the decay at injection of tune (quadrupolar components) and chromaticity (sextupolar components) of about 50% with respect to LHC Run1 due to the higher operational current. This paper discusses the beam-based measurements of the decay during the injection plateau and the implementation and accuracy of the feed-forward corrections as present in 2015. Moreover, the observed tune shift proportional to the circulating beam intensity and it's foreseen feed-forward correction are covered.

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TUPMW037

Luminosity Targets for FCC-hh

luminosity, collider, proton, detector

1523

F. Zimmermann, M. Benedikt, X. Buffat, D. Schulte
CERN, Geneva, Switzerland

Funding: Supported by the European Commission under the Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and under the HORIZON 2020 project EuroCirCol, grant agreement 654305.
We discuss the choice of target values for the peak and integrated luminosity of a future high-energy frontier circular hadron collider (FCC-hh). We review the arguments on the physics reach of a hadron collider. Next we show that accelerator constraints will limit the beam current and the turnaround time. Taking these limits into account, we derive an expression for the ultimate integrated luminosity per year, depending on a possible pile-up limit imposed by the physics experiments. We finally benchmark our result against the planned two phases of FCC-hh.

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WEPMW027

The ERL-based Design of Electron-Hadron Collider eRHIC

electron, linac, luminosity, proton

2482

V. Ptitsyn, E.C. Aschenauer, I. Ben-Zvi, J.S. Berg, M. Blaskiewicz, S.J. Brooks, K.A. Brown, J.C. Brutus, O.V. Chubar, A.V. Fedotov, D.M. Gassner, H. Hahn, Y. Hao, A. Hershcovitch, H. Huang, W.A. Jackson, Y.C. Jing, R.F. Lambiase, V. Litvinenko, C. Liu, Y. Luo, G.J. Mahler, B. Martin, G.T. McIntyre, W. Meng, F. Méot, T.A. Miller, M.G. Minty, B. Parker, I. Pinayev, V.H. Ranjbar, T. Roser, J. Skaritka, R. Than, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, E. Wang, G. Wang, H. Witte, Q. Wu, C. Xu, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Recent developments of the ERL-based design of future high luminosity electron-hadron collider eRHIC focused on balancing technological risks present in the design versus the design cost. As a result a lower risk design has been adopted at moderate cost increase. The modifications include a change of the main linac RF frequency, reduced number of SRF cavity types and modified electron spin transport using a spin rotator. A luminosity-staged approach is being explored with a Nominal design (L ~ 10³³ cm^-2 s^-1) that employs reduced electron current and could possibly be based on classical electron cooling, and then with the Ultimate design (L > 10³⁴ cm^-2 s^-1) that uses higher electron current and an innovative cooling technique (CeC). The paper describes the recent design modifications, and presents the full status of the eRHIC ERL-based design.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW027

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WEPMW036

MERLIN Cleaning Studies with Advanced Collimator Materials for HL-LHC

scattering, collimation, simulation, proton

2514

A. Valloni, R. Bruce, A. Mereghetti, E. Quaranta, S. Redaelli
CERN, Geneva, Switzerland
R.B. Appleby
UMAN, Manchester, United Kingdom
J. Molson
LAL, Orsay, France
H. Rafique
University of Huddersfield, Huddersfield, United Kingdom

The challenges of the High-Luminosity upgrade of the Large Hadron Collider require improving the beam collimation system. An intense R&D program has started at CERN to explore novel materials for new collimator jaws to improve robustness and reduce impedance. Particle tracking simulations of collimation efficiency are performed using the code MERLIN which has been extended to include new materials based on composites. After presenting two different implementations of composite materials tested in MERLIN, we present simulation studies with the aim of studying the effect of the advanced collimators on the LHC beam cleaning.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW036

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WEPOY056

Beam-beam Simulations with Realistic Crab Crossing for the eRhic Ring-Ring Electron Beam

electron, proton, cavity, luminosity

3123

C. Montag
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The 15mrad beam crossing angle in the eRHIC ring-ring interaction region requires crab crossing of the 250GeV proton beam to restore the luminosity. Since the product of the RF voltage and the RF frequency of the crab cavities is constant for a given crossing angle, higher frequencies are preferred in order to limit the require voltage. However, the 20cm RMS proton bunch length provides an upper limit of the useable frequencies due to the significant curvature of the RF waveform over this bunch length. To study the effectof realistic crab cavities with a finite wavelength on electron beam-beamdynamics and to determine the potential need for higher harmonic crab cavities to linearize the kick a simulation code has been developed.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY056

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WEPOY058

Design of the 2015 Erhic Ring-Ring Interaction Region

electron, proton, neutron, quadrupole

3129

C. Montag, B. Parker
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The 2015 ring-ring design study of the electron-ion collider eRHIC aims at an e-p luminosity around 10³³ cm^-2 sec^-1 over a center-of-mass energy range from 32 to 141 GeV, while at the same time providing the required detector geometry and acceptance for the proposed physics program. The latest interaction region design will be presented.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY058

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THPMB042

Residual Orbit Correction Studies for the FCC-hh

quadrupole, dipole, alignment, photon

3332

D. Boutin, B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
A. Chancé, J. Payet
CEA/DSM/IRFU, France
B.J. Holzer, R. Martin, D. Schulte
CERN, Geneva, Switzerland

The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the three options considered for the next genera-tion accelerator in high-energy physics as recommended by the European Strategy Group [*]. Preliminary studies have started to estimate the design parameters of FCC-hh. One of these studies is the calculation of the residual orbit in the arcs of the collider. This is very important for the evaluation of the alignment tolerances of the quadru-poles used in the arcs, the dimensioning of the correctors and of the beam screen. Moreover it has an impact on the dynamic aperture of the ring and the field tolerances of the arc multipoles. To perform the simulations, the beam transport code MADX has been used. Systematic studies of the residual orbit and of the correctors' strength de-pendence on the magnets misalignment or field errors are presented and discussed.
[*] A. Ball et al., EDMS-0134202.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB042

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THPMB044

Limitations on Optics Measurements in the LHC

optics, dipole, injection, luminosity

3339

P.K. Skowroński, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, A. Langner, E.H. Maclean, L. Malina, M. McAteer, T. Persson, R. Tomás
CERN, Geneva, Switzerland
A. Langner
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
L. Malina
University of Oslo, Oslo, Norway

In preparation of the optics commissioning at an energy of 6.5 TeV, many improvements have been done to cope with the expected reduced signal to noise ratio due to lowered bunch intensities imposed by machine protection considerations. This included, among others, an increase of the flat top duration of the AC dipole excitations, which allowed to use more turn-by-turn data for the analysis. The longer data acquisition revealed slow drifts of the optics, which limited the increased measurement precision. Furthermore, we will present how orbit drifts influenced dispersion measurements and, as a consequence, posed another limitation for the optics correction. In this paper we will discuss the implications of these observations for the measurement and correction of the optics.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB044

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THPOY045

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

operation, dipole, injection, beam-losses

4203

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

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

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

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