Search

The Future Circular electron-positron Collider (FCC-ee) is a proposal for a 91.17 km collider, which would operate in four modes with energies ranging from 45.6 GeV (Z-pole) to 182.5 GeV (ttbar-production). At high energies the beam lifetime could be as low as 6 minutes, requiring the beam to be continuously topped up to reach a high integrated luminosity. This top-up injection would use a separate booster ring in the same tunnel as the collider, which would accelerate the beams to the collider energy. The booster ring should achieve a lower equilibrium emittance than the collider, despite challenges such as a long damping time and no magnet-strength tapering to compensate for the impact of synchrotron radiation. For top-up injection into the collider, we consider two strategies: conventional bump injection, employing a closed orbit bump, and injection using a multipole kicker magnet. On-axis and off-axis sub-schemes will be studied for both. We compare these injection strategies on aspects including spatial constraints, machine protection, perturbation to the stored beam and hardware parameters., Proceedings of the 65th ICFA Advanced Beam Dynamics Workshop on High Luminosity Circular e+e- Colliders, eeFACT2022, Frascati, Italy

The Super Proton Synchrotron (SPS) injection system plays a fundamental role to preserve the quality of injected high-brightness beams for the Large Hadron Collider (LHC) physics program and to maintain the maximum storable intensity. The present system is the result of years of upgrades and patches of a system not conceived for such intensities and beam qualities. In this study, we propose the design of a completely new injection system for the SPS using multi-level numerical optimisation, including realistic hardware assumptions. We also present how this hierarchical optimisation framework can be adapted to other situations for optimal accelerator system design.

The international FCC study group published in 2019 a Conceptual Design Report for an electron-positron collider with a centre-of-mass energy from 90 to 365 GeV with a beam currents of up to 1.4 A per beam. The high beam current of this collider create challenging requirements on the injection chain and all aspects of the linac need to be carefully reconsidered and revisited, including the injection time structure. The entire beam dynamics studies for the full linac, damping ring and transfer lines are major activities of the injector complex design. A key point is that any increase of positron production and capture efficiency reduces the cost and complexity of the driver linac, the heat and radiation load of the converter system, and increases the operational margin. In this paper we will give an overview of the status of the injector complex design and introduce the new layout that has been proposed by the study group working in the context of the CHART collaboration. In this framework, furthermore, we also present the preliminary studies of the FCC-ee positron source highlighting the main requirements and constraints., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

In order to maximize the luminosity production time in the FCC-ee, top-up injection will be employed. The positron and electron beams will be accelerated to the collision energy in the booster ring before being injected with either a small transverse or longitudinal separation to the stored beam. Using this scheme essentially keeps the beam current constant and, apart from a brief period during the injection process, collision data can be continuously acquired. Two top-up injection schemes, each with on- and off-momentum sub-schemes, viable for FCC-ee have been identified in the past and are studied in further detail to find a suitable design for each of the four operation modes of the FCC-ee. In this paper, injection straight optics, initial injection tracking studies and the effect on the stored beam are presented. Additionally, a basic proxy error lattice is introduced as a first step to studying injection into an imperfect machine., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

ELENA is a small synchrotron ring that decelerates antiprotons down to a kinetic energy of 100 keV. With an experimental complex capable of housing up to 9 different experiments operating simultaneously, the transfer line design needed to be highly flexible. The low energy of the beam transported allowed the exploitation of electrostatic devices instead of magnets, to simplify design, production and operation. This contribution presents the systematic characterisation of the beam optics at the different experimental handover locations during beam commissioning using H⁻ ions from an external source, as well as the performance of the lines in operation with antiprotons. Finally, the effect of stray fields created by the experimental setup will be presented and compared with the first measurements., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The SPS injection kicker magnets (MKP) were developed in the 1970’s, before beam induced power deposition was considered an issue. These magnets are very lossy from a beam impedance perspective: this is expected to be an issue during SPS operation with the higher intensity beams needed for HL-LHC. A design, with serigraphy applied to an alumina carrier, has been developed to significantly reduce the broadband beam coupling impedance and hence mitigate the heating issues. During high voltage pulse testing there were electrical discharges associated with the serigraphy. Detailed mathematical models have been developed to aid in understanding the transiently induced voltages and to reduce the magnitude and duration of electric field. In this paper, we discuss the solutions implemented to mitigate the electrical discharges while maintaining an adequately low beam-coupling impedance. In addition, the results of high voltage tests are reported. The alumina substrate has a high secondary electron yield and thus electron-cloud could be an issue, with SPS beam, if mitigating measures were not taken: this paper also discusses the measures implemented., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The Future Circular electron-positron Collider (FCC-ee) will have stored beam energies of up to 20 MJ. This is a factor 100 higher than any current or past lepton collider. A safe and reliable disposal of the beam onto a beam dump block is therefore critical for operation. To ensure the survival of the dump core blocks, transversal dilution of the beam is necessary. To reduce the complexity of the system and guarantee high availability, an optimized, semi-passive beam dumping system has been designed. The main dump absorber design has been optimized following recent studies for high energy dump block materials for the LHC High Luminosity upgrade. First simulations regarding the radiation environment of the dumping system have been carried out, allowing the definition of preliminary constraints for the integration with respect to radiation sensitive equipment. The performance of the system has been evaluated using Monte-Carlo simulations as well as thermomechanical Finite-Element-Analysis to investigate potential material failure and assess safety margins. An experiment at the CERN HiRadMat facility has been carried out and preliminary results show good agreement with simulations., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The LHC beam dump system is used for extracting beam from the LHC and, as such, is a safety critical system whose proper functionality must be assured. Dilution kicker magnets (MKBs) sweep the extracted beam over the cross-sectional area of a dump block as the energy density would otherwise be too high and damage the block. In 2018, a high voltage flashover occurred in a vertical MKB (MKBV) vacuum tank, during a beam dump, which resulted in non-ideal sweep of the beam over the block. The location of the flashover could not be identified during a subsequent inspection of the magnet. Hence, electrical field simulations have been carried out to identify potentially critical regions, to determine the most probable region of the flashover. One potentially critical region is a rectangular beam pipe (RBP) between the end of the tank and the MKBV magnet, whose purpose is to reduce plasma propagation to the adjacent tank in the event of a flashover. Mitigating measures were studied and are reported in this paper., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The Extra Low ENergy Antiproton ring ELENA is a small synchrotron recently constructed and commissioned to decelerate antiprotons injected from the Antiproton Decelerator AD with a kinetic energy of 5.3 MeV down to 100 keV. Controlled deceleration in the synchrotron, equipped with an electron cooler to reduce losses and generate dense bunches, allows the experiments, typically capturing the antiprotons in traps and manipulating them further, to improve the trapping efficiency by one to two orders of magnitude. During 2018, bunches with an energy of 100 keV with parameters close to nominal have been demonstrated, and first beams have been provided to an experiment in a new experimental zone. The magnetic transfer lines from the AD to the experiments have been replaced by electrostatic lines from ELENA. Commissioning of the new transfer lines and, in parallel, studies to better understand the ring with H⁻ beams from a dedicated source, have started in autumn 2020. The first 100 keV antiproton physics run using ELENA will start in late summer 2021., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The protection of the tertiary collimators (TCTs) and the LHC triplet aperture in case of a so-called asynchronous beam dump relies on the correct retraction between the TCTs and the dump region absorbers. A new method to validate this retraction has been proposed, and a proof-of-principle experiment was performed at the LHC. The method uses a long orbit bump to mimic the change of the beam trajectory caused by an asynchronous firing of the extraction kickers. It can, thus, be performed with circulating beam. This paper reports on the performed beam measurements, compares them with expectations and discusses the potential benefits of the new method for machine protection., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

In view of the smaller physical apertures of Nb3Sn magnets for the HE-LHC study, a machine study was performed in the LHC to tighten correspondingly the ring and injection protection collimators and measure the change in loss behaviour. The smaller physical apertures will result in significantly smaller normalised apertures than what is presently available in the LHC. This report will address the question of whether Hilumi beam types can be injected with tight collimator settings. The results presented in this study will show the measured injection losses as a function of collimator setting with the preliminary attempts to extrapolate to higher injected intensities. This extrapolation will enable limitations of the collimator settings to be identified.

This note summarises the LHC Machine Development (MD) 4044, which studied the beam-loss and quench behaviour during asynchronous beam dumps at injection and at top energy using bunched beam in the abort gap. The main MD results are presented together with energy-deposition studies and calculations of the relevant quench limits.

This note summarises the results of LHC Machine Development (MD) 2930, which studied the beam-loss behaviour during asynchronous beam dumps at 450 GeV and at 6.5 TeV using bunched beam in the abort gap. The MD consisted of three main parts. First, single pilot bunches were injected into the abort gap, dumped and the resulting beam loss patterns were recorded. Second, trains of 48 bunches were injected into the abort gap with successively increasing bunch intensity and dumped. No quenches of superconducting magnets were observed up to a bunch intensity of 1.25e11 protons. In the last part, single pilots were ramped to 6.5 TeV. The last dump caused the beam-induced quench of the MQY.4R6, the MB.A8R6 and the MQY.4L6 magnets.

This MD shows the feasibility of operating TI2 with an optics matched to the SPS Q22 optics.Optics studies in the transfer line (TL) were performed together with an injection voltage scan toassess, also, the longitudinal quality of the injected single bunch.

This report discusses the feasibility and limitations for operating the LHC and HL-LHC at the ultimate beam energy of 7.5 TeV, corresponding to a main dipole magnetic field of 8.93 T and an operating current of 12748 A.

The Large Hadron Collider (LHC) has successfully completed its second operational run of four years length in December 2018. Operation will be stopped during two years for maintenance and upgrades. To allow for the successful completion of the diverse physics program at 6.5 TeV, the LHC has been routinely operating with stored beam energies close to 300 MJ per beam during high intensity proton runs as well as being frequently reconfigured to allow for special physic runs and important machine developments. No significant damage has incurred to the protected accelerator equipment throughout the run thanks to the excellent performance of the various machine protection systems, however a number of important observations and new failure scenarios have been identified, which were studied experimentally as well as through detailed simulations. In this contribution, we provide an overview of the performance of the machine protection systems throughout Run 2 as well as the important lessons learnt that will impact consolidation actions and the upgrade of the machine protection systems for the LIU/HL-LHC era., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The fourth one-month Pb-Pb collision run brought LHC Run 2 to an end in December 2018. Following the tendency to reduce dependence on the configuration of the preceding proton run, a completely new optics cycle with the strongest ever focussing at the ALICE and LHCb experiments was designed and rapidly implemented, demonstrating the maturity of the collider’s operating modes. Beam-loss monitor thresholds were carefully adjusted to provide optimal protection from the multiple loss mechanisms in heavy-ion operation. A switch from a basic bunch-spacing of 100 ns to 75 ns was made as the beam became available from the injector chain. A new record luminosity, 6 times the original design and close to the operating value proposed for HL-LHC, provided validation of the strategy for mitigating quenches due to bound-free pair production (BFPP) at the interaction points of the ATLAS and CMS experiments. Most of the beam parameters of the HL-LHC Pb-Pb upgrade were attained during this run and the integrated luminosity goals for the first 10 years of LHC operation were substantially exceeded., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group. The latest changes brought to the lattice of the FCC-hh collider are commented: impact of the new intra-beam distance, efforts to increase the beam stay clear in the dispersion suppressors, tuning procedures, and updates on the insertions., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The LHC Beam Dump System is required to safely dispose of the energy of the stored beam. In order to reduce the energy density deposited in the beam dump, a dedicated dilution system is installed. On July 14, 2018, during a regular beam dump at 6.5 TeV beam energy, a high-voltage flashover of two vertical dilution kickers was observed, leading to a voltage breakdown and reduced dilution in the vertical plane. It was the first incident of this type since the start of LHC beam operation. In this paper, the flashover event is described and the implications analysed. Circuit simulations of the current in the magnet coil as well as simulations of the resulting beam sweep pattern are presented and compared with the measurements. The criticality of the event is assessed and implications for future failure scenarios are discussed., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group. The latest changes brought to the lattice of the FCC-hh collider are commented: impact of the new intra-beam distance, efforts to increase the beam stay clear in the dispersion suppressors, tuning procedures, and updates on the insertions.

The LHC turn-around time is impacted by the control of injection losses and trajectories. While shot-to-shot trajectory variations dominated the injection efficiency during LHC Run 1, several improvements of hardware and operational settings allowed for a high rate of successful injections during Run 2. Injection losses and trajectories are analysed and presented for the high intensity proton runs, as well as for different beam types used from the injectors. Based on this analysis, an outlook is shown for the HL-LHC era, where double the bunch intensity will have to be injected., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Transfer lines are used to connect accelerators or deliver beam to fixed target experiments. In the following sections the design steps of a transfer line are introduced, starting from back-of-the-envelope calculations. The second part focuses on matching tools for optics design and related hardware specifications. The third part collects special topics which can appear in beam lines., CERN Yellow Reports: School Proceedings, Vol 5 (2018): Proceedings of the CAS-CERN Accelerator School on Beam Injection, Extraction and Transfer

An upgrade of the LHC dilution kicker system (MKB) during LS2 foresees the new implementation of a MKB re-trigger mechanism. Immediate re-triggering of the remaining MKB in case of a pre-firing module through the currently existing re-trigger line will be enabled. A decoupling system in the re-trigger line is proposed to inhibit asynchronous extraction kicker triggering in case of such self-triggering MKBs. In this report, different design proposals for this decoupling mechanism are evaluated and reliability assessments for the newly introduced system are conducted.

This note summarises the beam-based measurements of the MKD rise time for both LHC beams performed during MD4 on December 2nd, 2017 and discusses the results.

The Future Circular Collider (FCC) study considers several injector scenarios for FCC-hh, the proposed 100~TeV centre of mass hadron collider located at CERN. The investigated options include amongst others to use the LHC at 3.3~TeV or a superconducting SPS at 1.3~TeV as a High Energy Booster (HEB). Due to the high energy of the injected proton beam and the short time constant of injection failures, a thorough consideration of potential failure cases is of major importance. Further attention has to be given to the fact that the injection is - as in LHC - located upstream of the side experiments. Failure scenarios are identified for both injector options, appropriate designs of injection protection schemes are proposed and first simulations are conducted to validate the protection efficiency., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

A core part of the Future Circular Collider (FCC) study is a high energy hadron-hadron collider with a circumference of nearly 100~km and a center of mass beam energy of 100~TeV. The energy stored in one beam at top energy is 8.3~GJ, more than 20 times that of the LHC beams. Due to the large damage potential of the FCC-hh beam, the design of the beam extraction system is dominated by machine protection considerations and the requirement of avoiding any material damage in case of an asynchronous beam dump. Erratic operation of one or more extraction kickers is a main contributor to asynchronous beam dumps. The presented study shows ways to reduce the probability and mitigate the impact of erratic kicker switching. Key proposals to achieve this include layout considerations, different hardware options and alternative reaction strategies in case of erratic extraction kicker occurrence. Based on these concepts, different solutions are evaluated and an optimized design for the FCC-hh extraction system is proposed., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The SPS at CERN currently uses a beam dumping system that is installed in the long straight section 1 (LSS1) of the SPS. This system consists of two beam stopper blocks for low and high energy beams, as well as two vertical and three horizontal kicker magnets, which deflect and dilute the beam on the dumps. Within the frame of the LHC injector upgrade project (LIU) the beam dumping system will be relocated to long straight section 5 (LSS5) and upgraded with an additional vertical kicker, new main switches and a single new beam dump, which covers the full energy range. The impact of a possible increase of the vertical kicker rise time on the beam has been studied in simulations with MAD-X for the different optics in the SPS. Furthermore, the impact on the beam in failure scenarios such as the non-firing of one kicker has been investigated. The results of these studies will be presented and discussed in this paper. Operational mitigation methods to deal with an increased rise time will also be discussed., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

One option for a future circular collider at CERN is to build a 13.5 TeV hadron synchrotron, or High Energy LHC (HE-LHC) in the LHC tunnel. Injection and dump systems will have to be upgraded to cope with the higher beam rigidity and increased damage potential of the beam. The required modifications of the beam transfer hardware are highlighted in view of technology advancements in the field of kicker switch technology. An optimised straight section optics is shown., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The detailed understanding of the beam-loss pattern in case of an asynchronous beam dump is essential for the safe operation of the future High Luminosity LHC (HL-LHC) with nearly twice the nominal LHC beam intensity, leading to correspondingly higher energy deposition on the protection elements. An asynchronous beam dump is provoked when the rise time of the extraction kickers is not synchronized to the 3 us long particle-free abort gap. Thus, particles that are not absorbed by dedicated protection elements can be lost on the machine aperture. Since asynchronous beam dumps are among the most critical failure cases of the LHC, experimental tests at low intensity are performed routinely. This paper reviews recent asynchronous beam dump tests performed in the LHC. It describes the test conditions, discusses the beam-loss behaviour and presents simulation and measurement results. In particular, it examines a test event from May 2016, which led to the quench of four superconducting magnets in the extraction region and which was studied by a dedicated beam experiment in December 2017., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

At injection into the CERN Proton Synchrotron (PS) a significant horizontal emittance blow-up of the present high brightness beams for the LHC is observed. A partial contribution to this effect is suspected to be an important mismatch between the dispersion function in the transfer line from the PS Booster (PSB) and the ring itself. This mismatch will be unacceptable in view of the beam parameters requested by the LHC Injectors Upgrade (LIU) project with high longitudinal emittance and momentum spread. To deliver the requested beam parameters the PSB-to-PS transfer line will be upgraded and the optics in the line changed to improve the matching from all the four PSB rings. A re-matching campaign from the PSB ring 3 has been carried out to evaluate the impact of the present optics mismatch as a source of emittance growth both in simulations and measurements., Proceedings of the 61\textsuperscript{st} ICFA ABDW on High-Intensity and High-Brightness Hadron Beams, HB2018, Daejeon, Korea

The CERN LHC beam dumping system comprises a series of septa and fast-pulsed kicker magnets for extracting the stored proton beams to the external beam dumps. Different absorbers in the extraction region protect superconducting magnets and other machine elements in case of abnormal beam aborts, where bunches are swept across the machine aperture. During Run 2 of the LHC, controlled beam loss experiments were carried out at 6.5 TeV probing the particle leakage from protection devices under realistic operation conditions. This paper presents particle shower simulations analyzing the energy deposition in superconducting coils and assessing if the observed magnet quenches are compatible with the presently known quench limits., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The LHC Beam Dump System is one of the most critical systems for reliable and safe operation of the LHC. A dedicated dilution system is required to sweep the beam over the front face of the graphite dump core in order to reduce the deposited energy density. The High Luminosity Large Hadron Collider (HL-LHC) project foresees to increase the total beam intensity in the ring by nearly a factor of two, resulting in a correspondingly higher energy deposition in the dump core. In this paper, the beam sweep pattern and energy deposition for the case of normal dilution as well as for the relevant failure cases are presented. The implications as well as possible mitigations and upgrade measures for the dilution system, such as decreasing the pulse-generator voltage, adding two additional kickers, and implementing a retrigger system, are discussed., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The AWAKE experiment reached all planned milestones during Run 1 (2016-18), notably the demonstration of strong plasma wakes generated by proton beams and the acceleration of externally injected electrons to multi-GeV energy levels in the proton driven plasma wakefields. During Run~2 (2021 - 2024) AWAKE aims to demonstrate the scalability and the acceleration of electrons to high energies while maintaining the beam quality. Assuming continued success of the AWAKE program, AWAKE will be in the position to use the AWAKE scheme for particle physics applications such as fixed target experiments for dark photon searches and also for future electron-proton or electron-ion colliders. With strong support from the accelerator and high energy physics community, these experiments could be installed during CERN LS3; integration and beam line design studies show the feasibility of a fixed target experiment in the AWAKE facility, downstream of the AWAKE experiment in the former CNGS area. The expected electrons on target for fixed target experiments exceeds the electrons on target by three to four orders of magnitude with respect to the current NA64 experiment, making it a very promising experiment in the search for new physics. Studies show that electrons can be accelerated to 70 GeV in a 130 m long plasma cell installed in an extended TI 2 extraction tunnel from SPS to the LHC and transported to collision with protons/ions from the LHC. The experiment would focus on studies of the structure of matter and QCD in a new kinematic domain. The AWAKE scheme offers great potential for future high energy physics applications and it is the right moment now to support further development of this technology leading to unique facilities.

This is the first report of a three volume study on the full energy exploitation of the LHC. The report summaries the necessary preparations and consolidation work and the potential performance reach for operating the LHC at its nominal beam energy of 7TeV.

This note summarises the measurements and observations performed during the LHC Machine Development concerning the injection of batches of 80 bunches for future “high performance reach” of the LHC.

The Future Circular Collider for hadrons (FCC-hh) will require a fast injection kicker system that is highly reliable and that does not limit accelerator performance. Important considerations in the design of such a system are machine protection constraints, collider filling factor and hence rise and fall times of the kicker magnet field. Fast rise time kicker magnets are generally ferrite loaded transmission line type magnets with a rectangular shaped aperture. The beam coupling impedance of the kicker magnets is crucial, as this can be a dominant contribution to beam instabilities. In addition, beam-induced heating of the ferrite yoke due to the real component of the longitudinal beam coupling impedance needs to be controlled: if the ferrite temperature exceeds the Curie point this impacts the ability to inject beam and hence the availability of the machine. This paper presents estimates for the beam induced power deposition in the ferrite yoke, based on a calculated FCC beam spectrum and an analytical model of longitudinal impedance for unshielded kicker magnets., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The 2016 LHC proton filling schemes generally used a spacing between injections of batches of bunches into SPS and LHC corresponding to the design report specification for the SPS and LHC injection kicker rise times, respectively. A reduction of the batch spacing can be directly used to increase luminosity without detrimental effects on beam stability, and with no increase in the number of events per crossing seen by the experiments. Measurements and simulations were performed in SPS and LHC to understand if a shorter injection kicker rise time and associated tighter batch spacing would lead to increased injection oscillations of the first and last bunches of a bunch train and eventually also a systematic growth of the transverse emittance. The results were used to define the minimum possible batch spacing for an acceptable emittance growth in LHC, with gains of reductions of about 10% possible in both machines. The results are discussed, including the potential improvement of the LHC luminosity for different filling schemes., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The increased bunch length demanded by the LHC Injectors Upgrade (LIU) project to mitigate emittance growth from space-charge on the PS injection plateau puts strong constraints on the rise-times of the recombination kickers in the transfer lines between the CERN Proton Synchrotron Booster (PSB) and the Proton Synchrotron (PS). A beam-based technique has been developed to validate the waveforms of the recombination kickers. In this paper high-resolution measurements are presented by extracting the intra-bunch deflection along bunches with lengths comparable to or longer than the rise-time of the kicker being probed. The methodology has been successfully applied to the three vertical recombination kickers named BT1. KFA10, BT4. KFA10 and BT2. KFA20, and benchmarked with direct measurements of the kicker field made using a magnetic field probe. This paper describes the beam-based technique, summarises the main characteristics of the measured waveforms, such as rise-time and flat-top ripple, and estimates their impact on beam brightness., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

In the framework of the LHC Injectors Upgrade (LIU) project, a beam-based technique has been developed for measuring the waveform the CERN Proton Synchrotron (PS) horizontal injection kicker, named KFA45. The technique avoids the need for tedious magnetic measurements, especially when a spare magnet is presently unavailable and measuring the operational magnet with a magnetic field probe is complicated by integration reasons. In this paper, the technique and results of the waveform measurements are summarised. The results already provide additional information in terms of waveform characterisation for the validation of numerical simulations and are of great interest for the future LIU performance upgrade., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

In the framework of the LHC Injector Upgrade (LIU) project an upgrade of the existing PS proton injection kicker system for 2 GeV operation is in progress. The upgrade is based on the operation of the existing kicker system in short circuit mode. This paper briefly reviews the deployed modifications to the system to obtain the specified reduction of pulse reflections unavoidably induced by such a configuration. The implementation of improvements to the magnet entry box, transmission cables and the short circuit plug with integrated LC-filter are described as well as tests and measurements during the 2016/17 annual shutdown. The impact of the residual pulse shape structure on the beam performance for the reference LIU beam is quantified. The paper concludes with a performance analysis, a comparison of measurements vs. simulations and an outlook to the remaining modifications during the next long shut down., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The Future Circular Collider for hadrons (FCC-hh) envisaged at CERN will require a High Energy Booster as injector. One option being studied is to reuse the 6.9 km circumference tunnel of the SPS to house a fast-ramping superconducting machine. This paper presents the conceptual design considerations for this superconducting single aperture accelerator (designated scSPS) which can be used to accelerate protons to an extraction energy of 1.3 TeV, both for FCC and for fixed target beam operation in CERN's North Area. As FCC injector this accelerator has to be used in a fast cycling mode to fulfil the FCC-hh requirements concerning filling time, which impacts directly the choice of magnet technology. The reliability and availability will also play important roles in the design, and the inclusion of a fixed target capacity also has significant implications for the lattice and layout. The cell design, magnet parameters, overall layout, design of the different insertion and performance estimates for specific applications will be presented and discussed., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The LHC performance during the proton-lead run in 2016 fully relied on a permanent monitoring and systematic improvement of the beam quality in all the injectors. The beam production and characteristics are explained in this paper, together with the improvements realized during the run from the source up to the flat top of the LHC. Transmission studies from one accelerator to the next as well as beam quality evolution studies during the cycle at each accelerator, have been carried out and are summarized in this paper. In 2016, the LHC had to deliver the beams to the experiments at two different energies, 4 Z TeV and 6.5 Z TeV. The properties of the beams at these two energies are also presented, Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The present LHC lling scheme uses a batch spacing which corresponds to the design report specication of the injection kicker rise time. A reduction of the batch spacing can be directly used to increase luminosity without detrimental eect on beam stability. Therefore, measurements were performed to understand if a tighter batch spacing would lead to increased injection oscillations of a the rst and last bunches of a bunch train and eventually also a growth of the transverse emittance. The results of theses measurement were used to dene the minimum possible batch spacing for an acceptable emittance growth. Another measurement was performed to test if a batch consisting of 320 bunches can be injected instead of the nominal 288 bunch trains. This bunch train is dierently produced in the LHC injectors and features an optimum between beam stability and luminosity gain. The pulse length of the injection kicker was measured to ensure the full batch can be injected at once.