IPAC2013 - List of Authors (De Maria, R.)

Paper	Title	Page
MOPWO026	Investigation of Numerical Precision Issues of Long Term Single Particle Tracking	942
	E. McIntosh, R. De Maria, M. Giovannozzi CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. Long term single particle simplectic tracking is one of the most reliable tool to study the dynamic aperture of the circular accelerators. The present computational performance allows to explore the long term behaviour for an extended number of turns. It is well known that for instance single precision floating point arithmetic introduces too much numerical noise even after a moderate number of turns. In this paper we explore the artefacts of the double precision arithmetic that may be visible when the number of turns is in the order of 10⁶, 10⁷.

MOPWO027	Improved TEAPOT Method and Tracking with Thick Quadrupoles for the LHC and its Upgrade	945
	H. Burkhardt, R. De Maria, M. Giovannozzi, T. Risselada CERN, Geneva, Switzerland
	The comparison between tracking with thick and thin lens models for the LHC have been studied. A widely-used method to generate thin models is based on the TEAPOT slicing, which, in the original implementation is limited in the number of slices. In this paper an improved method is presented, which overcomes some of the limitations of the original TEAPOT. The performance is analysed and the impact on numerical simulation of the dynamic aperture is evaluated, both for the LHC and its upgrade, HL-LHC.

MOPWO028	Recent Developments and Future Plans for SixTrack	948
	R. De Maria, R. Bruce, R. Calaga, L. Deniau, M. Fjellstrom, M. Giovannozzi, L. Lari, Y.I. Levinsen, E. McIntosh, A. Mereghetti, D. Pastor Sinuela, S. Redaelli, H. Renshall, A. Rossi, F. Schmidt, R. Tomás, V. Vlachoudis CERN, Geneva, Switzerland R. Appleby, D.R. Brett UMAN, Manchester, United Kingdom D. Banfi, J. Barranco EPFL, Lausanne, Switzerland B. Dalena CEA/IRFU, Gif-sur-Yvette, France L. Lari IFIC, Valencia, Spain V. Previtali Fermilab, Batavia, USA G. Robert-Demolaize BNL, Upton, Long Island, New York, USA
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. SixTrack is a symplectic 6D tracking code routinely used to simulate single particle trajectories in high energy circular machines like the LHC and RHIC. The paper presents the developments recently implemented and those foreseen for extending the physics models: exact Hamiltonian, different ions and charge states, RF multipoles, non-linear fringe fields, Taylor maps, e-lenses, ion scattering. Moreover new functionalities are also added like variable number of tracked particles, time dependent strengths, GPU computations with a refactoring of the core structure. The developments will benefit studies on the LHC and SPS, for collimation efficiency, ion operations, failure scenarios and HL-LHC design.

MOPWO042	Simulations of Collimation Cleaning Performance with HL-LHC Optics	987
	A. Marsili, R. Bruce, R. De Maria, S.D. Fartoukh, S. Redaelli CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The upgrade of the LHC from the current set-up to high luminosity performances will provide new challenges for the protection of the machine. The different optics considered might create new needs for collimation, and require new collimation locations. In order to evaluate the cleaning performances of the collimation system, different halo cleaning simulations were performed with the particle tracking code SixTrack. This paper presents the cleaning performance simulation results for the high luminosity Achromatic Telescopic Squeeze optics considered as baseline for the HL-LHC. The new limitations observed and possible solutions are discussed.

TUPFI001	High Luminosity LHC Matching Section Layout vs Crab Cavity Voltage	1328
	B. Dalena CEA/IRFU, Gif-sur-Yvette, France A. Chancé, J. Payet CEA/DSM/IRFU, France R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland
	Funding: The research leading to these results has received funding from the European Commission under the FP7 project HiLumi LHC, GA no. 284404, co-funded by the DoE, USA and KEK, Japan. In the framework of the HL-LHC Upgrade project we present a new possible variant for the layout of the LHC matching section located in the high luminosity insertions. This layout is optimized to reduce the demand on the voltage of the crab cavities, while substantially improving the optics squeeze-ability, both in ATS [1] and non-ATS mode. These new layout will be described in details together with its performance figures in terms of mechanical acceptance, chromatic properties and optics flexibility. [1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI014	HLLHCV1.0: HL-LHC Layout and Optics Models for 150 mm Nb3Sn Triplets and Local Crab-cavities	1358
	R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland A.V. Bogomyagkov BINP SB RAS, Novosibirsk, Russia M. Korostelev The University of Liverpool, Liverpool, United Kingdom
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The paper presents the latest layout and optics models for the HL-LHC upgrade project. As an evolution from the previous version SLHCV3.1b, it integrates the new Nb3Sn triplet (140T/m, 150mm) with all the additional magnets needed to be compatible with a β^* reach of 15cm and beyond. The collision optics implements the ATS* scheme which is able to provide very low value of β^* and at the same time warrants outstanding control of the chromatic aberrations within the strength limits of the existing arc sextupole scheme of the LHC. The optics models include the injection and collision optics for proton and ion operations foreseen for the HL-LHC, with improved squeeze-ability of the existing IR2 and IR8 insertions, and all the corresponding optic transitions. An aperture model and a series of optics matched in thin lenses complete the needs for a large range of dedicated beam dynamic studies (dynamic aperture, beam-beam effects, collimation). * S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI015	Study of the IR2 and IR8 Squeezeability for HL-LHC Upgrade	1361
	A.V. Bogomyagkov BINP SB RAS, Novosibirsk, Russia R. De Maria CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The paper presents the results of the study of different optics configurations which allow to reach smaller beta functions at the IP2 and IP8 in the framework of the HL-LHC project. The variants at collision energies must be compatible with the ATS* scheme which provides small beta function at the IP1 and IP5 or provide low beta function for Alice and LHCb during ion operatations. The ones at injection must satisfy injection transfer lines and aperture constraints. The final goal is to find the overlap between the phase advances of all the configuration for IR2 and IR8 respectively, in order to mainting the LHC working point without rematching the remaining insertions. * S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI016	Optimization of Triplet Quadrupoles Field Quality for the LHC High Luminosity Lattice at Collision Energy	1364
	Y. Nosochkov, Y. Cai, M.-H. Wang SLAC, Menlo Park, California, USA R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh CERN, Geneva, Switzerland
	Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515. For the high luminosity upgrade of the LHC (HL-LHC), the beta functions at two interaction points (IP) will be significantly reduced compared to the nominal LHC lattice. This will result in much higher peak beta functions in the inner triplet (IT) quadrupoles adjacent to these IPs. The consequences are a larger beam size in these quadrupoles, higher IT chromaticity, and stronger effects of the IT field errors on dynamic aperture (DA). The IT chromaticity will be compensated using the Achromatic Telescopic Squeezing scheme. The increased IT beam size will be accommodated by installing large aperture Nb3Sn superconducting quadrupoles with 150 mm coil diameter. The field error tolerances in these magnets must satisfy the required acceptable DA while being reasonably close to realistically achievable field quality. Evaluation of the IT field errors was performed for the LHC upgrade layout version SLHCV3.01 with IT gradient of 123 T/m and IP collision beta functions of 15 cm in both planes. Dynamic aperture calculations were performed using SixTrack. Details of the optimization of the IT field errors are presented along with corrections to achieve the field quality specifications. S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI017	Evaluation of Field Quality for Separation Dipoles and Matching Section Quadrupoles for the LHC High Luminosity Lattice at Collision Energy	1367
	Y. Nosochkov, Y. Cai, M.-H. Wang SLAC, Menlo Park, California, USA R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh CERN, Geneva, Switzerland
	Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515. The high luminosity upgrade of the LHC (HL-LHC) lattice requires new larger aperture magnets to be installed in the low-beta interaction regions (IRs). These include Nb3Sn superconducting (SC) triplet quadrupoles, Nb-Ti SC separation dipoles D1 and D2, and SC Q4 quadrupoles. The upgrade significantly reduces the beta functions at these IRs, producing higher beta functions and larger beam size in these magnets, and requiring a larger aperture. The high beta functions also increase the impact of high order field errors in these new magnets on dynamic aperture (DA). Therefore, to maintain an acceptable DA, new specifications for the magnet field quality are required. Since the IR error effects at collision are dominated by the triplets, their field quality has been studied and specified first. As a next step, the field errors were added to the D1 and D2 dipoles and Q4 quadrupoles while maintaining the triplet errors to specifications. The impact of the errors on DA has been determined in long term tracking simulations using SixTrack. The optimized field error specifications for the D1, D2 and Q4 magnets are presented. Y. Nosochkov, Y. Cai, M-H. Wang, S. Fartoukh, M. Giovannozzi, R. de Maria, E. McIntosh, “Optimization of Triplet Field Quality for the LHC High Luminosity Lattice at Collision Energy”, IPAC 2013.

TUPFI023	Optics Design and Lattice Optimisation for the HL-LHC	1385
	B.J. Holzer, R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland R. Appleby, S. Kelly, M.B. Thomas, L.N.S. Thompson UMAN, Manchester, United Kingdom A.V. Bogomyagkov BINP SB RAS, Novosibirsk, Russia A. Chancé CEA, Gif-sur-Yvette, France B. Dalena CEA/IRFU, Gif-sur-Yvette, France A. Faus-Golfe, J. Resta IFIC, Valencia, Spain K.M. Hock, M. Korostelev, L.N.S. Thompson, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom C. Milardi INFN/LNF, Frascati (Roma), Italy J. Payet CEA/DSM/IRFU, France A. Wolski The University of Liverpool, Liverpool, United Kingdom
	Funding: The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Cap. Spec. Progr, Grant Agreement 284404. The luminosity upgrade project of the LHC collider at CERN is based on a strong focusing scheme to reach smallest beam sizes at the collision points. Depending on the available magnet technology (Nb3Sn or NbTi) a number of beam optics has been developed to define the specifications for the new super conducting quadrupoles. In the context of the optics matching new issues have been addressed and new concepts have been used: Quadrupole strength flexibility and chromatic corrections have been studied, as well as the influence of quadrupole fringe fields. The lattice has been optimised including the needs of the foreseen crab cavities and the transition between injection and low β optics had to guarantee smooth gradient changes over a wide range of β* values. Tolerances on misalignments and power converter ripple have been re-evaluated. Finally the combination of the quadrupole strengths in the high luminosity matching sections with those in the neighboring sectors is explained, a key concept of the ATS to reach smallest β* values. This paper presents the results obtained within the HiLumi collaboration Task 2.2 and summarises the main parameters of the project.

TUPFI051	Optics Transition between Injection and Collision Optics for the HL-LHC Upgrade Project	1460
	M. Korostelev, A. Wolski The University of Liverpool, Liverpool, United Kingdom R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland M. Korostelev, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. Plans for the luminosity upgrade of the LHC collider at CERN (HL-LHC) are based on implementation of magnets with larger apertures in the interaction regions, together with the ATS [] technique to reach very low values of the beta function at the collision points. The transition from injection to collision optics will be carried out in two stages, and will involve varying the strengths of the quadrupoles within the straight sections. Solutions for the optics transition have to meet a variety of challenging constraints, including constraints on the phase advances and Twiss parameters throughout the straights involved in the transition, specified minimum and maximum strengths of the quadrupoles, etc. Moreover, to minimize the time taken for the transition, the variation of the quadrupole strengths should be as smooth as possible, especially for the strongest quadrupoles. Avoiding changes of slope as much as possible will also minimize hysteresis effects in the super-conducting matching quadrupoles participating to the process. This paper presents one possible solution for the optics transition, calculated for the HLLHCv1.0 version of the optics and layout of the HL-LHC. S. Fartoukh, "An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade", in proceedings of IPAC11, p. 2088.

WEPEA045	Specifications of the Field Quality at Injection Energy of the New Magnets for the HL-LHC Upgrade Project	2603
	R. De Maria, S.D. Fartoukh, M. Giovannozzi CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The HL-LHC project relies on new magnet designs and technologies to achieve very small β^* values. In particular, Nb3Sn magnets show large allowed multipole imperfections at low current. These field errors may have a non-negligible impact on the dynamic aperture and beam life time in the HL-LHC, also because of the smaller-than-nominal β^* values foreseen IR1 and IR5 at injection energy, which aims at decreasing the dynamic range of the squeeze and therefore contributing to optimize the turn around time. The paper describes an analysis of the machine performance based on analytical estimates and tracking simulations with the goal of providing field quality specifications for the new magnets.

WEPEA046	Experimental Observations from the LHC Dynamic Aperture Machine Development Study in 2012	2606
	M. Giovannozzi, S. Cettour Cave, R. De Maria, M. Ludwig, A. Macpherson, S. Redaelli, F. Roncarolo, M. Solfaroli Camillocci, W. Venturini Delsolaro CERN, Geneva, Switzerland
	In view of improving the understanding of the behaviour of the dynamic aperture and to benchmark the numerical simulations performed so far, two experimental sessions have been scheduled at the LHC. The observations of the first sessions have been reported elsewhere[1], while in this paper the latest observations in terms of beam currents, blm losses and beam sizes will be described. The octupolar spool pieces have been used to artificially reduce the dynamic aperture and then induced slow beam losses. Alternating signs have been used in order to probe different configurations. Finally, scans over the strength of the decapolar spool pieces have been performed too. [1] M. Giovannozzi et al., “First Experimental Observations from the LHC Dynamic Aperture Experiment”, in proceedings of IPAC12, p. 1362

WEPEA047	Dynamic Aperture Performance for Different Collision Optics Scenarios for the LHC Luminosity Upgrade	2609
	M. Giovannozzi, R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland A. Chancé, B. Dalena, J. Payet CEA/IRFU, Gif-sur-Yvette, France K.M. Hock, M. Korostelev, A. Wolski The University of Liverpool, Liverpool, United Kingdom J. Resta-López IFIC, Valencia, Spain
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The ATS[1] optics solution for the HL-LHC offers the possibility of different collision optics, with a β^* as small as 10 cm in both transverse planes, or with a β^* aspect ratio of up to 4 pushing β^* to even smaller value (5cm) in the parallel separation plane while relaxing it (20 cm) in the crossing plane. The latter configuration features two possible options for alternated orientations of the crossing plane in the two high luminosity insertions, both considered in this study. In this paper we study the impact of few selected field imperfection models of the new magnets foreseen for the upgrade through tracking simulations and scaling laws. [1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA048	Specification of a System of Correctors for the Triplets and Separation Dipoles of the LHC Upgrade	2612
	M. Giovannozzi, R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The luminosity upgrade of the LHC aims at reducing β^* from 55 cm to 15 cm or beyond. This can be achieved by the ATS* scheme and means of new large aperture superconducting triplet (IT) quadrupoles (150 mm), preferably using the Nb3Sn technology in order to keep the gradient reasonably high (140 T/m). The field quality requires careful specification in order to ensure a large enough dynamic aperture. In this context, dedicated corrector magnets are foreseen to provide semi-local corrections of specific multipole components and find the best possible compromise between the demand and what can be realistically achieved by the magnet manufacturer. In this paper the layout and main parameters of the IT corrector package are presented together with the correction strategy. Moreover, the foreseen performance is discussed in detail. * S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA049	Analysis of the Non-linear Fringe Effects of Large Aperture Triplets for the HL LHC Project	2615
	A.V. Bogomyagkov, E.B. Levichev, P.A. Piminov BINP SB RAS, Novosibirsk, Russia A. Chancé, B. Dalena, J. Payet CEA/IRFU, Gif-sur-Yvette, France R. De Maria, S.D. Fartoukh, M. Giovannozzi CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The HL-LHC project relies on large aperture quadrupoles which are compatible with the very large beam sizes in the inner triplets resulting from the strong reduction of β^*. As a result the beam is much more sensitive to non-linear perturbations in this region, such as those induced by the fringe fields of the low-beta quadrupoles. The spatial extension of these fringe fields increases as well more or less linearly with the coil aperture, which is an additional motivation to analyse this aspect in detail in the framework of the High Luminosity LHC design study. This paper will quantify this effect both by direct analytical estimates using first order Hamiltonian perturbation theory, and via numerical studies thanks to the dedicated implementation of a fringe field symplectic integrator in SixTrack.

WEPEA050	Analysis of Possible Functional Forms of the Scaling Law for Dynamic Aperture as a Function of Time	2618
	M. Giovannozzi, R. De Maria, F. Lang CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. In recent studies, the evolution of the dynamic aperture with time has been fitted with a simple scaling law based on a limited number of free parameters. In this paper, different approaches to improve the numerical stability of the fit are presented, together with a new functional form. The results are discussed in details and applied to a set of numerical simulations for the LHC.

WEPEA058	LSS Layout Optimizations for Low-beta Optics for the HL-LHC	2639
	B.J. Holzer, R. De Maria CERN, Geneva, Switzerland R. Appleby, L.N.S. Thompson UMAN, Manchester, United Kingdom L.N.S. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404 The High Luminosity LHC (HL-LHC) project aims to upgrade the existing LHC to a peak luminosity of the order 10³⁵cm^-2s⁻¹, while retaining as much of the nominal layout and hardware as possible. The current baseline for this upgrade is the use of the Achromatic Telescopic Squeeze (ATS) concept, which allows mini-Beta squeeze in IRs 1 and 5 (ATLAS and CMS respectively) far below that possible with nominal optics. However it is useful to both explore the parameter space of the ATS scheme while also attempting to push the boundaries of the nominal layout. This paper presents a study into maximising optical flexibility of the nominal LHC Long Straight Sections (LSSs) around IPs 1 and 5. This involves replacing, moving or adding magnets within the LSS to investigate feasibility of exploiting a more conventional optical scheme than the ATS scheme. In particular the option of replacing single LSS quadrupoles with doublets is explored. The study also looks at making similar changes to the LSS while also implementing the ATS scheme, to further explore the ATS parameter space with the benefit of experience gained into flexibility of a modified nominal LHC optical scheme.

WEPEA059	Study of the Impact of Fringe Fields of the Large Aperture Triplets on the Linear Optics of the HL-LHC	2642
	B.J. Holzer, R. De Maria, S. Russenschuck CERN, Geneva, Switzerland R. Appleby, S. Kelly, M.B. Thomas, L.N.S. Thompson UMAN, Manchester, United Kingdom L.N.S. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404 High-luminosity hadron colliders such as the High Luminosity LHC (HL-LHC) project place demanding requirements on existing and new magnet technology. The very low β^* achieved by the Achromatic Telescopic Squeeze (ATS) optics scheme* for the HL-LHC in particular, requires large apertures in the high gradient Nb3Sn final focusing inner triplet triplet. Such magnets have extended fringe fields which perturb the linear and non-linear optics. This paper presents results of studies into the liner optics of the LHC using a range of fringe field models, including measurements of fringe fields from prototype magnets, and presents calculations of the beta-beating in the machine. Furthermore a similar study is presented on the nominal LHC optics, which uses final focus quadrupoles of higher gradient but significantly smaller aperture. * S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA064	SixTrack-Fluka Active Coupling for the Upgrade of the SPS Scrapers	2657
	A. Mereghetti, F. Cerutti, R. De Maria, B. Goddard, V. Kain, M. Meddahi, Ö. Mete, Y. Papaphilippou, D. Pastor Sinuela, V. Vlachoudis CERN, Geneva, Switzerland R. Appleby UMAN, Manchester, United Kingdom
	The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Essential for the clean injection into the LHC, the SPS scrapers are one of the important systems under revision. In order to take into account of the effect of betatron and longitudinal beam dynamics on energy deposition patterns, and nuclear and Coulomb scattering in the absorbing medium onto loss patterns, the SixTrack and Fluka codes have been coupled, profiting from the best of the refined physical models they respectively embed. The coupling envisages an active exchange of tracked particles between the two codes at each turn, and an on-line aperture check in SixTrack, in order to estimate the local cleaning inefficiency of the system. Knob-like, time-dependent strengths have been implemented in SixTrack, since the designed scraper system foresees the use of a magnetic bump. The study is intended to assess the robustness of the proposed scraper as well as its effectiveness with respect to the desired performance.

WEPEA076	Comparison of Taylor Maps with Radio Frequency Multipoles in a Thin Lens 6D Tracking Code	2687
	D.R. Brett, R. Appleby UMAN, Manchester, United Kingdom J. Barranco, R. De Maria, R. Tomás CERN, Geneva, Switzerland
	Funding: HiLumi LHC Design Study is part of the High Luminosity LHC project and is part funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. SixTrack is a general purpose 6D thin lens tracking code used for dynamic aperture studies. In the high luminosity LHC upgrade it is proposed that crab cavities are used to enhance the luminosity. In this study, for the current proposed optics, we consider the use of RF multipoles and Taylor maps as methods to simulate crab cavity elements in the lattice.

Paper

Title

Page

Investigation of Numerical Precision Issues of Long Term Single Particle Tracking

942

E. McIntosh, R. De Maria, M. Giovannozzi
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Long term single particle simplectic tracking is one of the most reliable tool to study the dynamic aperture of the circular accelerators. The present computational performance allows to explore the long term behaviour for an extended number of turns. It is well known that for instance single precision floating point arithmetic introduces too much numerical noise even after a moderate number of turns. In this paper we explore the artefacts of the double precision arithmetic that may be visible when the number of turns is in the order of 10⁶, 10⁷.

MOPWO027

Improved TEAPOT Method and Tracking with Thick Quadrupoles for the LHC and its Upgrade

945

H. Burkhardt, R. De Maria, M. Giovannozzi, T. Risselada
CERN, Geneva, Switzerland

The comparison between tracking with thick and thin lens models for the LHC have been studied. A widely-used method to generate thin models is based on the TEAPOT slicing, which, in the original implementation is limited in the number of slices. In this paper an improved method is presented, which overcomes some of the limitations of the original TEAPOT. The performance is analysed and the impact on numerical simulation of the dynamic aperture is evaluated, both for the LHC and its upgrade, HL-LHC.

MOPWO028

Recent Developments and Future Plans for SixTrack

948

R. De Maria, R. Bruce, R. Calaga, L. Deniau, M. Fjellstrom, M. Giovannozzi, L. Lari, Y.I. Levinsen, E. McIntosh, A. Mereghetti, D. Pastor Sinuela, S. Redaelli, H. Renshall, A. Rossi, F. Schmidt, R. Tomás, V. Vlachoudis
CERN, Geneva, Switzerland
R. Appleby, D.R. Brett
UMAN, Manchester, United Kingdom
D. Banfi, J. Barranco
EPFL, Lausanne, Switzerland
B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
L. Lari
IFIC, Valencia, Spain
V. Previtali
Fermilab, Batavia, USA
G. Robert-Demolaize
BNL, Upton, Long Island, New York, USA

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
SixTrack is a symplectic 6D tracking code routinely used to simulate single particle trajectories in high energy circular machines like the LHC and RHIC. The paper presents the developments recently implemented and those foreseen for extending the physics models: exact Hamiltonian, different ions and charge states, RF multipoles, non-linear fringe fields, Taylor maps, e-lenses, ion scattering. Moreover new functionalities are also added like variable number of tracked particles, time dependent strengths, GPU computations with a refactoring of the core structure. The developments will benefit studies on the LHC and SPS, for collimation efficiency, ion operations, failure scenarios and HL-LHC design.

MOPWO042

Simulations of Collimation Cleaning Performance with HL-LHC Optics

987

A. Marsili, R. Bruce, R. De Maria, S.D. Fartoukh, S. Redaelli
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The upgrade of the LHC from the current set-up to high luminosity performances will provide new challenges for the protection of the machine. The different optics considered might create new needs for collimation, and require new collimation locations. In order to evaluate the cleaning performances of the collimation system, different halo cleaning simulations were performed with the particle tracking code SixTrack. This paper presents the cleaning performance simulation results for the high luminosity Achromatic Telescopic Squeeze optics considered as baseline for the HL-LHC. The new limitations observed and possible solutions are discussed.

TUPFI001

High Luminosity LHC Matching Section Layout vs Crab Cavity Voltage

1328

B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
A. Chancé, J. Payet
CEA/DSM/IRFU, France
R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland

Funding: The research leading to these results has received funding from the European Commission under the FP7 project HiLumi LHC, GA no. 284404, co-funded by the DoE, USA and KEK, Japan.
In the framework of the HL-LHC Upgrade project we present a new possible variant for the layout of the LHC matching section located in the high luminosity insertions. This layout is optimized to reduce the demand on the voltage of the crab cavities, while substantially improving the optics squeeze-ability, both in ATS [1] and non-ATS mode. These new layout will be described in details together with its performance figures in terms of mechanical acceptance, chromatic properties and optics flexibility. [1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI014

HLLHCV1.0: HL-LHC Layout and Optics Models for 150 mm Nb3Sn Triplets and Local Crab-cavities

1358

R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland
A.V. Bogomyagkov
BINP SB RAS, Novosibirsk, Russia
M. Korostelev
The University of Liverpool, Liverpool, United Kingdom

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The paper presents the latest layout and optics models for the HL-LHC upgrade project. As an evolution from the previous version SLHCV3.1b, it integrates the new Nb3Sn triplet (140T/m, 150mm) with all the additional magnets needed to be compatible with a β^* reach of 15cm and beyond. The collision optics implements the ATS* scheme which is able to provide very low value of β^* and at the same time warrants outstanding control of the chromatic aberrations within the strength limits of the existing arc sextupole scheme of the LHC. The optics models include the injection and collision optics for proton and ion operations foreseen for the HL-LHC, with improved squeeze-ability of the existing IR2 and IR8 insertions, and all the corresponding optic transitions. An aperture model and a series of optics matched in thin lenses complete the needs for a large range of dedicated beam dynamic studies (dynamic aperture, beam-beam effects, collimation).
* S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI015

Study of the IR2 and IR8 Squeezeability for HL-LHC Upgrade

1361

A.V. Bogomyagkov
BINP SB RAS, Novosibirsk, Russia
R. De Maria
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The paper presents the results of the study of different optics configurations which allow to reach smaller beta functions at the IP2 and IP8 in the framework of the HL-LHC project. The variants at collision energies must be compatible with the ATS* scheme which provides small beta function at the IP1 and IP5 or provide low beta function for Alice and LHCb during ion operatations. The ones at injection must satisfy injection transfer lines and aperture constraints. The final goal is to find the overlap between the phase advances of all the configuration for IR2 and IR8 respectively, in order to mainting the LHC working point without rematching the remaining insertions.
* S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI016

Optimization of Triplet Quadrupoles Field Quality for the LHC High Luminosity Lattice at Collision Energy

1364

Y. Nosochkov, Y. Cai, M.-H. Wang
SLAC, Menlo Park, California, USA
R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh
CERN, Geneva, Switzerland

Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515.
For the high luminosity upgrade of the LHC (HL-LHC), the beta functions at two interaction points (IP) will be significantly reduced compared to the nominal LHC lattice. This will result in much higher peak beta functions in the inner triplet (IT) quadrupoles adjacent to these IPs. The consequences are a larger beam size in these quadrupoles, higher IT chromaticity, and stronger effects of the IT field errors on dynamic aperture (DA). The IT chromaticity will be compensated using the Achromatic Telescopic Squeezing scheme*. The increased IT beam size will be accommodated by installing large aperture Nb3Sn superconducting quadrupoles with 150 mm coil diameter. The field error tolerances in these magnets must satisfy the required acceptable DA while being reasonably close to realistically achievable field quality. Evaluation of the IT field errors was performed for the LHC upgrade layout version SLHCV3.01 with IT gradient of 123 T/m and IP collision beta functions of 15 cm in both planes. Dynamic aperture calculations were performed using SixTrack. Details of the optimization of the IT field errors are presented along with corrections to achieve the field quality specifications.
* S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI017

Evaluation of Field Quality for Separation Dipoles and Matching Section Quadrupoles for the LHC High Luminosity Lattice at Collision Energy

1367

Y. Nosochkov, Y. Cai, M.-H. Wang
SLAC, Menlo Park, California, USA
R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh
CERN, Geneva, Switzerland

Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515.
The high luminosity upgrade of the LHC (HL-LHC) lattice requires new larger aperture magnets to be installed in the low-beta interaction regions (IRs). These include Nb3Sn superconducting (SC) triplet quadrupoles, Nb-Ti SC separation dipoles D1 and D2, and SC Q4 quadrupoles. The upgrade significantly reduces the beta functions at these IRs, producing higher beta functions and larger beam size in these magnets, and requiring a larger aperture. The high beta functions also increase the impact of high order field errors in these new magnets on dynamic aperture (DA). Therefore, to maintain an acceptable DA, new specifications for the magnet field quality are required. Since the IR error effects at collision are dominated by the triplets, their field quality has been studied and specified first*. As a next step, the field errors were added to the D1 and D2 dipoles and Q4 quadrupoles while maintaining the triplet errors to specifications. The impact of the errors on DA has been determined in long term tracking simulations using SixTrack. The optimized field error specifications for the D1, D2 and Q4 magnets are presented.
* Y. Nosochkov, Y. Cai, M-H. Wang, S. Fartoukh, M. Giovannozzi, R. de Maria, E. McIntosh, “Optimization of Triplet Field Quality for the LHC High Luminosity Lattice at Collision Energy”, IPAC 2013.

TUPFI023

Optics Design and Lattice Optimisation for the HL-LHC

1385

B.J. Holzer, R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland
R. Appleby, S. Kelly, M.B. Thomas, L.N.S. Thompson
UMAN, Manchester, United Kingdom
A.V. Bogomyagkov
BINP SB RAS, Novosibirsk, Russia
A. Chancé
CEA, Gif-sur-Yvette, France
B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
A. Faus-Golfe, J. Resta
IFIC, Valencia, Spain
K.M. Hock, M. Korostelev, L.N.S. Thompson, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C. Milardi
INFN/LNF, Frascati (Roma), Italy
J. Payet
CEA/DSM/IRFU, France
A. Wolski
The University of Liverpool, Liverpool, United Kingdom

Funding: The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Cap. Spec. Progr, Grant Agreement 284404.
The luminosity upgrade project of the LHC collider at CERN is based on a strong focusing scheme to reach smallest beam sizes at the collision points. Depending on the available magnet technology (Nb3Sn or NbTi) a number of beam optics has been developed to define the specifications for the new super conducting quadrupoles. In the context of the optics matching new issues have been addressed and new concepts have been used: Quadrupole strength flexibility and chromatic corrections have been studied, as well as the influence of quadrupole fringe fields. The lattice has been optimised including the needs of the foreseen crab cavities and the transition between injection and low β optics had to guarantee smooth gradient changes over a wide range of β* values. Tolerances on misalignments and power converter ripple have been re-evaluated. Finally the combination of the quadrupole strengths in the high luminosity matching sections with those in the neighboring sectors is explained, a key concept of the ATS to reach smallest β* values. This paper presents the results obtained within the HiLumi collaboration Task 2.2 and summarises the main parameters of the project.

TUPFI051

Optics Transition between Injection and Collision Optics for the HL-LHC Upgrade Project

1460

M. Korostelev, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland
M. Korostelev, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Plans for the luminosity upgrade of the LHC collider at CERN (HL-LHC) are based on implementation of magnets with larger apertures in the interaction regions, together with the ATS [*] technique to reach very low values of the beta function at the collision points. The transition from injection to collision optics will be carried out in two stages, and will involve varying the strengths of the quadrupoles within the straight sections. Solutions for the optics transition have to meet a variety of challenging constraints, including constraints on the phase advances and Twiss parameters throughout the straights involved in the transition, specified minimum and maximum strengths of the quadrupoles, etc. Moreover, to minimize the time taken for the transition, the variation of the quadrupole strengths should be as smooth as possible, especially for the strongest quadrupoles. Avoiding changes of slope as much as possible will also minimize hysteresis effects in the super-conducting matching quadrupoles participating to the process. This paper presents one possible solution for the optics transition, calculated for the HLLHCv1.0 version of the optics and layout of the HL-LHC.
* S. Fartoukh, "An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade", in proceedings of IPAC11, p. 2088.

WEPEA045

Specifications of the Field Quality at Injection Energy of the New Magnets for the HL-LHC Upgrade Project

2603

R. De Maria, S.D. Fartoukh, M. Giovannozzi
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The HL-LHC project relies on new magnet designs and technologies to achieve very small β^* values. In particular, Nb3Sn magnets show large allowed multipole imperfections at low current. These field errors may have a non-negligible impact on the dynamic aperture and beam life time in the HL-LHC, also because of the smaller-than-nominal β^* values foreseen IR1 and IR5 at injection energy, which aims at decreasing the dynamic range of the squeeze and therefore contributing to optimize the turn around time. The paper describes an analysis of the machine performance based on analytical estimates and tracking simulations with the goal of providing field quality specifications for the new magnets.

WEPEA046

Experimental Observations from the LHC Dynamic Aperture Machine Development Study in 2012

2606

M. Giovannozzi, S. Cettour Cave, R. De Maria, M. Ludwig, A. Macpherson, S. Redaelli, F. Roncarolo, M. Solfaroli Camillocci, W. Venturini Delsolaro
CERN, Geneva, Switzerland

In view of improving the understanding of the behaviour of the dynamic aperture and to benchmark the numerical simulations performed so far, two experimental sessions have been scheduled at the LHC. The observations of the first sessions have been reported elsewhere[1], while in this paper the latest observations in terms of beam currents, blm losses and beam sizes will be described. The octupolar spool pieces have been used to artificially reduce the dynamic aperture and then induced slow beam losses. Alternating signs have been used in order to probe different configurations. Finally, scans over the strength of the decapolar spool pieces have been performed too.
[1] M. Giovannozzi et al., “First Experimental Observations from the LHC Dynamic Aperture Experiment”, in proceedings of IPAC12, p. 1362

WEPEA047

Dynamic Aperture Performance for Different Collision Optics Scenarios for the LHC Luminosity Upgrade

2609

M. Giovannozzi, R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland
A. Chancé, B. Dalena, J. Payet
CEA/IRFU, Gif-sur-Yvette, France
K.M. Hock, M. Korostelev, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
J. Resta-López
IFIC, Valencia, Spain

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The ATS[1] optics solution for the HL-LHC offers the possibility of different collision optics, with a β^* as small as 10 cm in both transverse planes, or with a β^* aspect ratio of up to 4 pushing β^* to even smaller value (5cm) in the parallel separation plane while relaxing it (20 cm) in the crossing plane. The latter configuration features two possible options for alternated orientations of the crossing plane in the two high luminosity insertions, both considered in this study. In this paper we study the impact of few selected field imperfection models of the new magnets foreseen for the upgrade through tracking simulations and scaling laws.
[1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA048

Specification of a System of Correctors for the Triplets and Separation Dipoles of the LHC Upgrade

2612

M. Giovannozzi, R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The luminosity upgrade of the LHC aims at reducing β^* from 55 cm to 15 cm or beyond. This can be achieved by the ATS* scheme and means of new large aperture superconducting triplet (IT) quadrupoles (150 mm), preferably using the Nb3Sn technology in order to keep the gradient reasonably high (140 T/m). The field quality requires careful specification in order to ensure a large enough dynamic aperture. In this context, dedicated corrector magnets are foreseen to provide semi-local corrections of specific multipole components and find the best possible compromise between the demand and what can be realistically achieved by the magnet manufacturer. In this paper the layout and main parameters of the IT corrector package are presented together with the correction strategy. Moreover, the foreseen performance is discussed in detail.
* S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA049

Analysis of the Non-linear Fringe Effects of Large Aperture Triplets for the HL LHC Project

2615

A.V. Bogomyagkov, E.B. Levichev, P.A. Piminov
BINP SB RAS, Novosibirsk, Russia
A. Chancé, B. Dalena, J. Payet
CEA/IRFU, Gif-sur-Yvette, France
R. De Maria, S.D. Fartoukh, M. Giovannozzi
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The HL-LHC project relies on large aperture quadrupoles which are compatible with the very large beam sizes in the inner triplets resulting from the strong reduction of β^*. As a result the beam is much more sensitive to non-linear perturbations in this region, such as those induced by the fringe fields of the low-beta quadrupoles. The spatial extension of these fringe fields increases as well more or less linearly with the coil aperture, which is an additional motivation to analyse this aspect in detail in the framework of the High Luminosity LHC design study. This paper will quantify this effect both by direct analytical estimates using first order Hamiltonian perturbation theory, and via numerical studies thanks to the dedicated implementation of a fringe field symplectic integrator in SixTrack.

WEPEA050

Analysis of Possible Functional Forms of the Scaling Law for Dynamic Aperture as a Function of Time

2618

M. Giovannozzi, R. De Maria, F. Lang
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
In recent studies, the evolution of the dynamic aperture with time has been fitted with a simple scaling law based on a limited number of free parameters. In this paper, different approaches to improve the numerical stability of the fit are presented, together with a new functional form. The results are discussed in details and applied to a set of numerical simulations for the LHC.

WEPEA058

LSS Layout Optimizations for Low-beta Optics for the HL-LHC

2639

B.J. Holzer, R. De Maria
CERN, Geneva, Switzerland
R. Appleby, L.N.S. Thompson
UMAN, Manchester, United Kingdom
L.N.S. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404
The High Luminosity LHC (HL-LHC) project aims to upgrade the existing LHC to a peak luminosity of the order 10³⁵cm^-2s⁻¹, while retaining as much of the nominal layout and hardware as possible. The current baseline for this upgrade is the use of the Achromatic Telescopic Squeeze (ATS) concept, which allows mini-Beta squeeze in IRs 1 and 5 (ATLAS and CMS respectively) far below that possible with nominal optics. However it is useful to both explore the parameter space of the ATS scheme while also attempting to push the boundaries of the nominal layout. This paper presents a study into maximising optical flexibility of the nominal LHC Long Straight Sections (LSSs) around IPs 1 and 5. This involves replacing, moving or adding magnets within the LSS to investigate feasibility of exploiting a more conventional optical scheme than the ATS scheme. In particular the option of replacing single LSS quadrupoles with doublets is explored. The study also looks at making similar changes to the LSS while also implementing the ATS scheme, to further explore the ATS parameter space with the benefit of experience gained into flexibility of a modified nominal LHC optical scheme.

WEPEA059

Study of the Impact of Fringe Fields of the Large Aperture Triplets on the Linear Optics of the HL-LHC

2642

B.J. Holzer, R. De Maria, S. Russenschuck
CERN, Geneva, Switzerland
R. Appleby, S. Kelly, M.B. Thomas, L.N.S. Thompson
UMAN, Manchester, United Kingdom
L.N.S. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404
High-luminosity hadron colliders such as the High Luminosity LHC (HL-LHC) project place demanding requirements on existing and new magnet technology. The very low β^* achieved by the Achromatic Telescopic Squeeze (ATS) optics scheme* for the HL-LHC in particular, requires large apertures in the high gradient Nb3Sn final focusing inner triplet triplet. Such magnets have extended fringe fields which perturb the linear and non-linear optics. This paper presents results of studies into the liner optics of the LHC using a range of fringe field models, including measurements of fringe fields from prototype magnets, and presents calculations of the beta-beating in the machine. Furthermore a similar study is presented on the nominal LHC optics, which uses final focus quadrupoles of higher gradient but significantly smaller aperture.
* S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for
LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA064

SixTrack-Fluka Active Coupling for the Upgrade of the SPS Scrapers

2657

A. Mereghetti, F. Cerutti, R. De Maria, B. Goddard, V. Kain, M. Meddahi, Ö. Mete, Y. Papaphilippou, D. Pastor Sinuela, V. Vlachoudis
CERN, Geneva, Switzerland
R. Appleby
UMAN, Manchester, United Kingdom

The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Essential for the clean injection into the LHC, the SPS scrapers are one of the important systems under revision. In order to take into account of the effect of betatron and longitudinal beam dynamics on energy deposition patterns, and nuclear and Coulomb scattering in the absorbing medium onto loss patterns, the SixTrack and Fluka codes have been coupled, profiting from the best of the refined physical models they respectively embed. The coupling envisages an active exchange of tracked particles between the two codes at each turn, and an on-line aperture check in SixTrack, in order to estimate the local cleaning inefficiency of the system. Knob-like, time-dependent strengths have been implemented in SixTrack, since the designed scraper system foresees the use of a magnetic bump. The study is intended to assess the robustness of the proposed scraper as well as its effectiveness with respect to the desired performance.

WEPEA076

Comparison of Taylor Maps with Radio Frequency Multipoles in a Thin Lens 6D Tracking Code

2687

D.R. Brett, R. Appleby
UMAN, Manchester, United Kingdom
J. Barranco, R. De Maria, R. Tomás
CERN, Geneva, Switzerland

Funding: HiLumi LHC Design Study is part of the High Luminosity LHC project and is part funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
SixTrack is a general purpose 6D thin lens tracking code used for dynamic aperture studies. In the high luminosity LHC upgrade it is proposed that crab cavities are used to enhance the luminosity. In this study, for the current proposed optics, we consider the use of RF multipoles and Taylor maps as methods to simulate crab cavity elements in the lattice.