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In order to achieve higher instantaneous and integrated luminosities, the average Au bunch intensity in RHIC has been increased by 30% compared to the preceding Au run. This increase was accomplished by merging bunches in the RHIC injector AGS. Luminosity leveling for one of the two interaction points (IP) with collisions was realized by continuous control of the vertical beam separation. Parallel to RHIC physics operation, the electron beam commissioning of a novel cooling technique with potential application in eRHIC, Coherent electron Cooling as a proof of principle (CeCPoP), was carried out. In addition, a 56 MHz superconducting RF cavity was commissioned and made operational. In this paper we will focus on the RHIC performance during the 2016 Au-Au run., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

A Muon Collider promises unique opportunities both as an energy frontier machine and as a factory for detailed study of the Higgs boson and other particles. However, in order to achieve a competitive level of luminosity a number of demanding requirements to the collider optics should be satisfied arising from short muon lifetime and relatively large values of the transverse emittance and momentum spread in muon beams that can realistically be obtained with ionization cooling. Basic solutions which make possible to achieve these goals with Nb3Sn magnet parameters are presented., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

The kink instability limits the performance of a potential linac-ring based electron-ion collider design. In this paper, we report on the simulation study of the kink instability using a self-consistent strong-strong beam-beam model., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

The current baseline design for the JLab EIC (JLEIC) ion accelerator complex is based on a pulsed superconducting linac, an 8-GeV booster followed by a dual function 20-100 GeV booster and collider ring. Both the 8-GeV booster and collider ring will use super-ferric magnets with fields up to 3 Tesla. We here propose an alternative cost-effective and low-risk design where the 8-GeV booster is replaced with a more compact 3-GeV booster using room-temperature magnets. The electron storage ring, which is part of the electron complex, will also serve as large booster for the ions, up to 11 GeV. We also propose two stages for the JLEIC. A first low-energy stage up to 60 GeV, where room-temperature magnets (up to 1.6 Tesla) will be used for the ion collider ring, to be later replaced with 6 Tesla superconducting magnets in a second stage of the project providing up to 200 GeV energy. In this second stage, the 1.6 T room-temperature magnets will replace the PEP-II magnets in the electron storage ring to boost the ions to higher energies (25 GeV or higher) for appropriate injection into the higher energy collider. Details and feasibility of the proposed plan will be presented and discussed., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

LHC operation restarted in 2015 after the first Long Shutdown, planning for a 4-year long run until the end of 2018 (called Run 2). The beam energy was fixed at 6.5 TeV. The year 2015 was dedicated to establishing operation at the high energy and with 25 ns beams, in order to prepare production for the following three years. The year 2016 was the first one dedicated to production, and it turned out to be a record-breaking year, in which the goals in both peak and integrated luminosities with proton-proton beams were achieved and surpassed. This paper revisits 2015 and 2016, shortly highlighting the main facts in the timelines, recalling the parameters that characterized luminosity production, and sketching the main limitations and the main highlights of results for selected topics, including a particular focus on the beam physics issues., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

The energy scale for new physics is known to be in the multi-TeV range, signaling the potential need for a collider beyond the LHC. A 10³⁴ cm**−2 s**−1 luminosity 100 TeV proton-antiproton collider is explored. Prior engineering studies for 233 and 270 km circumference tunnels were done for Illinois dolomite and Texas chalk signaling manageable tunneling costs. At a ppbar the cross section for high mass states is of order 10x higher with antiproton collisions, where antiquarks are directly present rather than relying on gluon splitting. The higher cross sections reduce the synchrotron radiation in superconducting magnets, because lower beam currents can produce the same rare event rates. In our design the increased momentum acceptance (11 ± 2.6 GeV/c) in a Fermilab-like antiproton source is used with septa to collect 12x more antiprotons in 12 channels. For stochastic cooling, 12 cooling systems would be used, each with one debuncher/momentum equalizer ring and two accumulator rings. One electron cooling ring would follow. Finally antiprotons would be recycled during runs without leaving the collider ring, by joining them to new bunches with synchrotron damping., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

Diversified Technologies, Inc. (DTI) has designed, built, and demonstrated a prototype pulse amplifier for stripline kicker service capable of less than 5 ns rise and fall times, 5 to 90 ns pulse lengths, peak power greater than 13.7 MW at pulse repetition rates exceeding 100 kHz, and measured jitter under 100 ps. The resulting pulse is precise and repeatable, and will be of great interest to accelerator facilities requiring electromagnetic kickers. The pulse generator is based on the original specifications for the NGLS fast deflector. DTI's planar inductive adder configuration uses compensated-silicon power transistors in low inductance leadless packages with a novel charge-pump gate drive to achieve unmatched performance. The unit was brought to LBNL, compared with other researcher's efforts, and was judged very favorably. A number of development prototypes have been constructed and tested, including a successful 18.7 kV, 749 A unit. The modularity of this design will enable configuration of systems to a wide range of potential applications in both kickers and other high speed requirements, including high performance radars, directed energy systems, and excimer lasers., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

At the energies envisioned for the FCC-ee the synchrotron radiation produces not only closed orbit effects but also some dynamics effects including strong "beta-synchrotron" coupling due to radiation in the final focus quadrupoles. Past experience with LEP and other machines as well as the implications for the new wave of circular electron collider proposals will be discussed., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

The Jefferson Lab Electron-Ion Collider (JLEIC) is being designed to achieve a high luminosity of up to 10³⁴ 1/(cm²*sec). The latter requires a small beam size at the interaction point demanding a strong final focus (FF) quadrupole system. The strong beam focusing in the FF unavoidably creates a large chromaticity which has to be compensated in order to avoid a severe degradation of momentum acceptance. This has to be done while preserving sufficient dynamic aperture. An additional design requirement for the chromaticity compensation optics in the electron ring is preservation of the low beam emittance. This paper reviews the development and selection of a chromaticity correction scheme for the electron collider ring., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

Development of the superconducting RF crab cavities is one of the major activities under the high luminosity LHC upgrade project that aims to increase the machine discovery potential. The crab cavities will be used for maximizing and leveling the LHC luminosity hence having tight tolerances for the operating voltage and phase. RF field stability in its turn is sensitive to Lorentz force and external loads, so an accurate modelling of these effects is very important. Using the massively parallel ACE3P simulation suite developed at SLAC, we perform a corresponding multiphysics analysis of the electro-mechanical interactions for the RFD crab cavity design in order to ensure the operational reliability of the LHC crabbing system., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

In the JLab Electron Ion Collider (JLEIC) project the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during the collision at the collider ring. Different with other electron coolers using DC electron beam, the proposed electron cooler at the JLEIC ion collider ring uses high energy bunched electron beam, provided by an ERL. In this paper, we report some recent simulation study on how the electron cooling rate will be affected by the bunched electron beam properties, such as the correlation between the longitudinal position and momentum, the bunch size, and the Larmor emittance., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

Since 1960's, particle colliders have been in the forefront of particle physics, 29 total have been built and operated, 7 are in operation now. At present the near term US, European and international strategies of the particle physics community are centered on full exploitation of the physics potential of the Large Hadron Collider (LHC) through its high-luminosity upgrade (HL-LHC). The future of the world-wide HEP community critically depends on the feasibility of possible post-LHC colliders. The concept of the feasibility is complex and includes at least three factors: feasibility of energy, feasibility of luminosity and feasibility of cost. Here we overview all current options for post-LHC colliders from such perspective (ILC, CLIC, Muon Collider, plasma colliders, CEPC, FCC, HE-LHC) and discuss major challenges and accelerator R&D required to demonstrate feasibility of an energy frontier accelerator facility following the LHC. We conclude by taking a look into ultimate energy reach accelerators based on plasmas and crystals, and discussion on the perspectives for the far future of the accelerator-based particle physics. This paper largely follows previous study and the presentation given at the ICHEP'2016 conference in Chicago., 4 pp. arXiv admin note: text overlap with arXiv:1511.01934, arXiv:1509.08369

Low emittance muon beam lines and muon colliders are potentially a rich source of BSM physics for future experimenters. A normalized transverse muon emittance of 280 microns has been achieved in simulation with short solenoids and a betatron function of 3 cm. Here we use ICOOL, G4Beamline, and MAD-X to explore using a flat 400 MeV/c muon beam and strong focusing quadrupoles to achieve a normalized transverse emittance of 100 microns and finish 6D cooling. The low beta regions, as low as 5 mm, produced by the quadrupoles are occupied by dense, low Z absorbers, such as lithium hydride or beryllium, that cool the beam. Equilibrium transverse emittance is linearly proportional to the beta function. Reverse emittance exchange with septa and/or wedges is then used to decrease transverse emittance from 100 to 25 microns at the expense of longitudinal emittance for a high energy lepton collider. Cooling challenges include chromaticity correction, momentum passband overlap, quadrupole acceptance, and staying in phase with RF., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

To combat triplets vibration, the global orbit feedback system with frequency about 10 Hz was developed and en- gaged in operation at injection and top energy in 2010, dur- ing beam acceleration in 2012 at RHIC. The system has performed well with keeping 6 out of 12 eigenvalues for the orbit response matrix. However, we observed correc- tor current transients with the lattice for polarized proton program in 2015 which resulted in corrector power supply trips. In this report, we will present the observation, an- alyze the cause and also optimize the feedback algorithm to overcome the newly emerged problem with the feedback system., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

The figure-8 JLEIC collider ring opens wide possibilities for manipulating proton and deuteron spin directions during an experiment. Using 3D spin rotators, one can, at the same time, efficiently control the polarization direction as well as the spin tune value. The 3D spin rotators allow one to arrange a system for reversals of the spin direction in all beam bunches during an experiment, i.e. a spin-flipping system. To preserve the polarization, one has to satisfy the condition of adiabatic change of the spin direction. When adjusting the polarization direction, one can stabilize the spin tune value, which completely eliminates resonant beam depolarization during the spin manipulation process. We provide the results of numerical modeling of a spin-flipping system in the JLEIC ion collider ring. The presented results demonstrate the feasibility of organizing a spin-flipping system using a 3D rota-tor. The figure-8 JLEIC collider provides a unique capability of doing high-precision experiments with polarized ion beams., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

A design is presented for a hadron collider in which the magnetic storage ring is configured as a circular pipeline, supported in neutral buoyancy in the sea at a depth of ~100 m. Each collider detector is housed in a bathysphere the size of the CMS hall at LHC, also neutral-buoyant. Each half-cell of the collider lattice is ~300 m long, housed in a single pipe that contains one dipole, one quadrupole, a correction package, and all umbilical connections. A choice of ~4 T dipole field, 2000 km circumference provides a collision energy of 700 TeV. Beam dynamics is dominated by synchrotron radiation damping, which sustains luminosity for >10 hours. Issues of radiation shielding and abort can be accommodated inexpensively. There are at least ten sites world-wide where the collider could be located, all near major urban centers. The paper summarizes several key issues; how to connect and disconnect half-cell segments of the pipeline at-depth using remote submersibles; how to maintain the lattice in the required alignment; provisions for the injector sequence., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

RadiaBeam Technologies is currently developing a non-linear magnet insert for Fermilab's Integrable Optics Test Accelerator (IOTA), a 150 MeV circulating electron beam storage ring designed for investigating advanced beam physics concepts. The physics requirements of the insert demand a high level of precision in magnet geometry, magnet axis alignment, and corresponding alignment of the vacuum chamber geometry within the magnet modules to maximize chamber aperture size. Here we report on the design and manufacturing of the vacuum chamber, magnet manufacturing, and kinematic systems., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

The transfer line for beam extraction from the Recycler ring to P1 line provides a way to deliver 8 GeV kinetic energy protons from the Booster to the Delivery ring, via the Recycler, using existing beam transport lines, and without the need for new civil construction. It was designed in 2012. The kicker magnets at RR520 and the lambertson magnet at RR522 in the RR were installed in 2014 Summer Shutdown, the elements of RR to P1 Stub (permanent quads, trim quads, correctors, BPMs, the toroid at 703 and vertical bending dipole at V703 (ADCW) ) were installed in 2015 Summer Shutdown. On Tuesday, June 21, 2016, beam line from the Recycler Ring to P1 line was commissioned. The detailed results will be presented in this report., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

The original design of the JLEIC pre-booster was a 3-GeV figure-8 shaped synchrotron with a circumference of about 240 m. In the current baseline design, the 3-GeV pre-booster was converted into an 8-GeV booster of the same shape and size but using super-ferric magnets with fields up to 3 Tesla. In order to limit the foot-print of the JLEIC ion complex and reduce its total cost, we have designed a more compact and cost-effective octagonal 3-GeV ring about half the size of the original one. At 3 GeV, the figure-8 shape is not required to preserve ion polarization; Siberian snakes with reasonable magnetic fields can be used for spin correction. As the ion collider ring requires an injection energy of at least 8 GeV, we propose to use the existing electron storage ring, which is part of the electron complex, as a large booster for the ions up to 11 GeV. The design optimization of the pre-booster ring will be presented leading to the final octagonal ring design. Preliminary beam simulations will also be presented and discussed., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

An overview of the eRHIC project., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

A pulsed multi ion injector linac is being developed by ANL for Jefferson Laboratory's Electron Ion Collider (JLEIC). The linac is designed to deliver both polarized and non polarized ion beams to the booster synchrotron at energies ranging from 135 MeV for hydrogen to 43 MeV/u for lead ions. The linac is composed of a 5 MeV/u room temperature section and a superconducting section with variable velocity profile for different ion species. This paper presents the results of the RF design of the main components and the beam dynamics simulations of the linac front-end with the goal of achieving design specifications cost-effectively., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

Euclid Techlabs is developing a superconducting traveling wave (SCWT) cavity with a feedback waveguide [1] and has demonstrated a traveling wave at room temperature [2] in a 3-cell SCTW cavity [3]. A special method described in this paper was developed for cavity evaluation. It is based on an S-matrix approach. The cavity tuning procedure based on this method is described., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

The Muon Accelerator Program has completed a four-year study on the feasibility of muon colliders and on using stored muon beams for neutrinos. That study was broadly successful in its goals, establishing the feasibility of lepton colliders from the 125 GeV Higgs Factory to more than 10 TeV, as well as exploring using μ storage rings for neutrinos. The key components of the muon collider scenarios are a high-intensity proton source, a multi MW target and transport system for π capture, a front end system for bunching, energy compression and initial cooling of μ's, muon cooling systems to obtain intense μ+ and μ- bunches, acceleration up to multiTeV energies, and a collider ring with detectors for high luminosity collisions. For a neutrino factory a similar system could be used but with a racetrack storage ring for ν production and without the cooling needed for high luminosity collisions. Feasible designs and detailed simulations of all of these components have been obtained, including some initial hardware component tests, setting the stage for future implementation where resources are available and clearly associated physics goals become apparent., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

The SuperKEKB B-Factory at KEK (Japan), after few years of shutdown for the construction and renovation, has finally come to the Phase-1 commissioning of the LER and HER rings, without the final focus system and the Belle II detector. Vacuum scrubbing, optics tuning and beam related background measurements were performed in this phase. Low emittance tuning techniques have also been applied in order to set up the rings for Phase-2 with colliding beams next year. An update of the final focus system construction, as well as the status of the injection system with the new positron damping ring and high current/low emittance electron gun is also presented., Proceedings of the North American Particle Accelerator Conf., NAPAC2016, Chicago, IL, USA

Renewed interest in circular e+e- colliders has spurred designs of single beam-pipe machines, like the CEPC in China, and double beam pipe ones, such as the FCC-ee effort at CERN. Single beam-pipe designs profit from lower costs but are limited by the number of bunches that can be accommodated in the machine. We analyse these performance limitations and propose a solution that can accommodate O(1000) bunches while keeping more than 90% of the ring with a single beam pipe., Comment: Poster presented at IPAC'15, Richmond, VA, USA, May 2015

For the HL-LHC beam spot sizes as small as 7 mum are considered for the high luminosity insertions IR1 and IR5. In addition, the luminosity has to be levelled over several hours by changing β^{*} resulting in constant changes of the optics and thus orbit changes. The small beam size and the continuous optics changes in general make the alignment of the beams at the IP challenging. In order to avoid continuous luminosity scans for the alignment of the beams at the IP, the orbit correction has to rely on the readings of the BPMs in the IT region. In this paper we review the requirements on resolution and accuracy of the BPMs and compare different options for the placement of the BPMs in the IT region., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

In the High Luminosity LHC (HL-LHC), the collimation system will be upgraded in the high-luminosity experimental regions. Additional protection is planned for the Q4 and Q5 magnets that are located further upstream of the tertiary collimators that protect the inner triplet magnets. We evaluate the effect of this proposed collimation layout for the incoming beam 1 on machine-induced background in the experimental area of IR1 (ATLAS). The main scenario is the round optics with β∗ of 15 cm, but a flat scenario is also briefly discussed., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

Longitudinal bunch length splitting was observed for some LHC beams. In this paper, we will report on the study of the observation using strong-strong beam-beam simulations. We explore a variety of factors including initial momentum deviation, collision crossing angle, synchroton tune, chromaticity, working points and bunch intensity that contribute to the beam particle loss and the bunch length splitting, and try to understand the underlying mechanism of the observed phenomena., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

For the HL-LHC, β^{*} values as small as 15 cm are envisaged as baseline scenario for the high luminosity insertions IR1 and IR5, thus leading to an increase of the maximum beta-functions in the inner triplet (IT). The larger beta-functions in the IT result in a higher sensitivity of the beam to any linear or non-linear, static or dynamic, field imperfections in the IT region. In this paper, we summarize accordingly the tolerances of the triplet power supplies in terms of current ripple, stability and reproducibility. Both the baseline IT powering scheme and other alternative schemes will be presented, the later reducing the tune shift caused by a current modulation and thus weakening its possible impact on the long term stability., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The betatron collimators in IR7 constitute the backbone of the collimation system of the LHC. A fraction of the secondary halo protons or heavy-ion fragments, scattered out of the primary collimator, is not captured by the secondary collimators but hit cold magnets in the IR7 dispersion suppressor (DS) where the dispersion starts to increase. A possible approach to reduce these losses is based on the installation of additional collimators in the DS region. In this paper, simulations of the cleaning efficiency for Pb⁸²⁺ ions are used to evaluate the effect of the additional collimators. The results indicate a significant improvement of the heavy-ion cleaning efficiency., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

Recirculating linear accelerators (RLAs) are a cost-effective method for the acceleration of muons for a muon collider in energy ranges from a couple GeV to a few 10s of GeV. Muon beams generally have longitudinal emittances that are large for the RF frequency that is used, and it is important to limit the growth of that longitudinal emittance. This has particular consequences for the arc design of the RLAs. I estimate the longitudinal emittance growth in an RLA arising from the RF nonlinearity. Given an emittance growth limitation and other design parameters, one can then compute the maximum momentum compaction in the arcs. I describe how to obtain an approximate arc design satisfying these requirements based on the deisgn in Bogacz (2005)*. Longitudinal dynamics also determine the energy spread in the beam, and this has consequences on the transverse phase advance in the linac. This in turn has consequences for the arc design due to the need to match beta functions. I combine these considerations to discuss design parameters for the acceleration of muons for a collider in an RLA from 5 to 63 GeV., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The institute of High Energy Physics has proposed an electron positron collider ring with a circumference of 50-100km to study the Higgs boson. Since the proposal was made, the lattice design for CEPC has been carried out and a preliminary conceptual design report has been written at the end of 2014. In this paper, we will describe the philosophy and results of our lattice design. The procedure of dynamic aperture optimization will be shown. A specific issue for CEPC, the pretzel orbit, which has been found distorting the linear lattice for a considerable amount, will be examined. The ways that we are trying to correct the pretzel orbit effect and the result will be shown. We will also discuss the saw tooth effect on the linear lattice and dynamic aperture of the ring., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The HL-LHC will store 675 MJ of energy per beam, about 300 MJ more than the nominal LHC. Due to the increase in stored energy and a different interaction region (IR) optics design, the collimation system for the incoming beam must be revisited in order to avoid dangerous losses that could cause quenches and machine damage. This paper studies the ffectiveness of the current LHC collimation system in intercepting cleaning losses close to the experiments in the HL-LHC. The study reveals that additional tertiary collimators would be beneficial in order to protect not only the final focusing triplets but also the two quadrupoles further upstream., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The feasibility of Future Circular Colliders (FCC), possible successors to the Large Hadron Collider (LHC), is currently under investigation at CERN. This paper describes how CERN’s civil engineering team are utilising an interactive tool containing a 3D geological model of the Geneva basin. This tool will be used to investigate the optimal position of the proposed 80km-100km tunnel. The benefits of using digital modelling during the feasibility stage are discussed and some early results of the process are presented., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

Beam-beam effects of the ring-ring scheme of FCC-he and LHeC are being studied using weak-strong simulations. The beam-beam tune shift of the electron beam is one order larger than that of proton beam. The study of the electron motion under the beam-beam interaction is the main subject. Luminosity and equilibrium beam size and beam lifetime are analysed., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

We report on modeling results for synchrotron radiation absorption in the SuperKEKB positron storage ring vacuum chamber including the effects of photon scattering on the interior walls. A detailed model of the geometry of the inner vacuum chamber profile has been developed and used as input to a photon tracking code. Particular emphasis is placed on the photon absorption rates in the electron-positron interaction region., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

CEPC (Circular Electron and Positron Collider) is a circular Higgs Factory with optimized energy 240 GeV. In order to achieve luminosity as high as 2×10³⁴/cm²/s, CEPC calls for a small vertical beta function at IP (betay∗=1.2 mm) which was provided by the final focus of the interaction region. In this paper, a preliminary design of the CEPC interaction region was presented. The optimization of dynamic aperture with interaction region insertion and the machine detector interface was discussed as well., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The main emphasis of the Future Circular Collider study is the design of a 100~TeV proton-proton collider in a new tunnel of about 100 km circumference. This paper presents the first optics design of the future hadron collider (FCC-hh). The basic layout follows a quasi-circular geometry ‘‘quasi racetrack'' with 8 arcs and 8 straight sections, four of which designed as interaction points. Assuming 16~T dipole magnets, a first version of the ring geometry and magnet lattice is presented, including the optics of the foreseen high luminosity regions and of the other straight sections dedicated to the installation of injection/extraction lines, beam dump etc., and an arc structure with optimized dipole fill factor to reach the target center-of-mass energy of 100~TeV., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The optics and layout of the HL-LHC are evolving as the new hardware is being studied and integrated, any additional requirements from the experiments detailed, and other constraints of different nature clarified. Here we present the changes of version 1.1 of the optics and layout with respect to the previous version 1.0, which include the current hardware choices and an outlook on the main resulting optics limitations and the possible future evolutions of the layout., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The first part of RHIC Run 15 consisted of nine weeks of polarized proton on proton collisions at a beam energy of 100 GeV at two interaction points. In this paper we discuss several of the upgrades to the collider complex that allowed for improved performance this run. The largest effort consisted of commissioning of the electron lenses, one in each ring, which are designed to compensate one of the two beam-beam interactions experienced by the proton bunches. The e-lenses therefore raise the per bunch intensity at which luminosity becomes beam-beam limited. A new lattice was designed to create the phase advances necessary for a functioning e-lens which also has an improved off-momentum dynamic aperture relative to previous runs. In order to take advantage of the new, higher intensity limit without suffering intensity driven emittance deterioration, other features were commissioned including a continuous transverse bunch-by-bunch damper in RHIC and a double harmonic capture scheme in the Booster. Other high intensity protections include improvements to the abort system and the installation of masks to intercept beam lost due to abort kicker pre-fires., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

This presentation reviews the status of the high luminosity LHC project, and highlights the main challenges from the technology and beam physics point of view. It will mention the outcome of the 2015 Cost and Schedule review for the HL-LHC project and summarizes the status of the high field quadrupole and crab cavity development., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

High Luminosity-LHC is the future upgrade of the LHC that aims at delivering an integrated luminosity of 3000 fb-1 over about 10 years of operation, starting from 2025. Significant modifications [1] will be implemented to accelerator systems, including new superconducting magnets, crab cavities, superconducting links, new collimators and absorbers based on advanced materials and design and additional cryo-plants. Due to the limit imposed by the number of simultaneous events at the experiments (pile-up) on peak luminosity, the latter will be levelled to 5*1034 cm⁻²s^{−1}. The target integrated luminosity can only be achieved with a significant increase of the total available time for beam collisions compared to the 2012 LHC run, despite a beam current that is planned to double the nominal 0.58 A. Therefore one of the key figures of merit to take into account for system upgrades and new designs is their impact on the accelerator availability. In this paper the main factors affecting LHC availability will be discussed and predictions on the impact of future system upgrades on integrated luminosity presented. Requirements in terms of the maximum allowed number of dumps for the main contributing systems to LHC unavailability will be derived., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

Hollow electron lenses are considered as a possible mean to improve the LHC beam collimation system, providing an active control of halo diffusion rates and suppressing the population of transverse halos. After a very successful experience at the Tevatron, a conceptual design of a hollow e-lens optimized for the LHC was produced. Recent further studies have led to a mature preliminary technical design. In this paper, possible scenarios for the deployment of this technology at the LHC are elaborated in the context of the scheduled LHC long shutdowns until the full implementation of the HL-LHC upgrade in 2023. Possible setups of electron beam test stands at CERN and synergies with other relevant electron beam programmes outside CERN are also discussed., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The final cooling system for a high-energy high-luminosity muon collider requires reduction of the transverse emittance by an order of magnitude to ~0.00003 m (rms, N), while allowing longitudinal emittance increase to ~0.1m. In the present baseline approach, this is obtained by transverse cooling of low-energy muons within a sequence of high field solenoids with low-frequency rf systems. Recent studies of such systems are presented. Since the final cooling steps are actually emittance exchange a variant form of that final system can be obtained by a round to flat transform in x-y, with transverse slicing of the enlarged flat transverse dimension followed by longitudinal recombination of the sliced bunchlets. Development of final exchange following lowest-emittance cooling is discussed., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

One of the key design features of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab is a small beta function at the interaction point (IP) allowing one to achieve a high luminosity of up to 10³⁴ cm⁻²s⁻¹. The required strong beam focusing unavoidably causes large chromatic effects such as chromatic tune spread and beam smear at the IP, which need to be compensated. This paper reports recent progress in our development of a chromaticity correction scheme for the ion ring including optimization of dynamic aperture and momentum acceptance., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

The baseline design of CLIC (Compact Linear Collider) uses X-band accelerating structures in the main linac. Every accelerating structure cell has four waveguides, terminated with individual RF loads, to damp the unwanted long-range transverse wakefields, in order to maintain beam stability in multi-bunch operation. In order to experimentally verify the calculated suppression of the wakefields, a prototype structure has been built and installed in FACET test facility at SLAC. The results of the measurements of the wakefields in the prototype structure by means of positron and electron bunches are presented., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

For high luminosity in a muon collider, muon bunches that have been cooled in the six-dimensional helical cooling channel (HCC) must be merged into a single bunch and further cooled in preparation for acceleration and transport to the collider ring. The helical bunch coalescing channel has been previously simulated [*, **] and provides the most natural match from helical upstream and downstream subsystems. This work focuses on the matching from the exit of the multiple bunch HCC into the start of the helical bunch coalescing channel. The simulated helical matching section simultaneously matches the helical spatial period λ in addition to providing the necessary acceleration for efficient bunch coalescing. Previous studies assumed that the acceleration of muon bunches from p=209.15 MeV/c to 286.816 MeV/c and matching of λ from 0.5 m to 1.0 m could be accomplished with zero particle losses and zero emittance growth in the individual bunches. This study demonstrates nonzero values for both particle loss and emittance growth, and provides considerations for reducing these adverse effects to best preserve high luminosity., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

A known threat to the availability of the LHC is the interaction of macroparticles (dust particles) with the LHC proton beam. At the foreseen beam energy of 6.5 TeV during Run 2, quench margins in the superconducting magnets will be 2-3 times lower, and beam losses due such interactions may result in magnet quenches. The study introduce an improved numerical model of such interactions, as well as Monte-Carlo simulations that give the probability that such events will result in a beam-dump during Run 2., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

RHIC polarized proton Run 15 uses a new acceleration ramp optics, compared to RHIC Run~14 and earlier runs, in relation with electron-lens beam-beam compensation developments. The new optics induces different strengths in the depolarizing snake resonance sequence, from injection to top energy. As a consequence, polarization transport along the new ramp has been investigated, based on spin tracking simulations. Sample results are reported and discussed., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

We present a new optimized design of the accelerating structure for the main linac of CLIC (Compact Linear Collider). The new structure has lower surface magnetic fields and a significantly smaller transverse size compared to the baseline design described in the CLIC Concept Design Report (CDR). This new design should reach higher accelerating gradients and have a reduced manufacturing cost. The details of the RF design procedure and the obtained results are presented in this paper., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA