The purpose of the study is to determine which clinical indications benefit most and by how much from minimizing and holding a proton scanning spot size constant over the range 150-230 MeV in comparison to existing systems and techniques. The objective of improved therapeutic quality for the indications is assessed by the resulting conformity index for the targets and organ at risk sparing in comparison to existing proton therapy systems and techniques. Modeling and measurements were used to predict proton spot size values. The resulting technical parameters were used to facilitate treatment planning of a sampling of clinical indications. The components of a proton therapy LINAC were modeled using multi-particle tracking codes. Matching of the beam transport line was performed to keep the beam size focused in the wide energy range between 150 to 230 MeV. Based on modeling and measurement, a beam model was produced in a commercial treatment planning system (TPS) representing energies up to 230 MeV. The TPS was used to produce comparative treatment plans for an intracranial brain tumor, a prostate, and head and neck tumor cases. The plan comparisons are between a representative cyclotron beam and the Linac beam model. Unlike the spot enlargement observed with decreasing energy for cyclotrons, the Linac spot size was found to be invariant (constant) between energies 150-230 MeV. The resulting proton Linac treatment plans were shown to be more conformal than the cyclotron-based plans. Although all the clinical cases evaluated benefited from the invariant spot size, the intracranial and prostate cases were the most improved. It is suggested that this is a result of their need for relatively higher energies. A proton Linac has been evaluated for proton therapy applications. Several attractive properties of the proton therapy Linac have been observed. Here, we report on the transverse beam properties, which are expected to improve dose conformity for patient targets falling within the range 150-230 MeV of fixed 3 mm sigma beam size. The proton Linac and its successive evolutions are subject to conformity assessment and market authorization.

In the article of Migliorati, Aumon, Koukovini-Platia, Huschauer, Metral, Sterbini and Wang [Phys. Rev. Accel. Beams 21, 120101 (2018)], hereafter the Article and the Authors, the long-standing qualification of the PS instability as the transverse mode-coupling instability, or TMCI, is not mentioned, while a model of the beam breakup (BBU) is discussed. Do the observations and modeling of the Article refute the long-standing idea that the PS instability is the TMCI?

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100TeV. Its unprecedented centre of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries.

In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in the same 100 km tunnel. The scientific capabilities of the integrated FCC programme would serve the worldwide community throughout the 21st century. The FCC study also investigates an LHC energy upgrade, using FCC-hh technology. This document constitutes the second volume of the FCC Conceptual Design Report, devoted to the electron-positron collider FCC-ee. After summarizing the physics discovery opportunities, it presents the accelerator design, performance reach, a staged operation scenario, the underlying technologies, civil engineering, technical infrastructure, and an implementation plan. FCC-ee can be built with today’s technology. Most of the FCC-ee infrastructure could be reused for FCC-hh. Combining concepts from past and present lepton colliders and adding a few novel elements, the FCC-ee design promises outstandingly high luminosity. This will make the FCC-ee a unique precision instrument to study the heaviest known particles (Z, W and H bosons and the top quark), offering great direct and indirect sensitivity to new physics.

The FCC-ee project studies the design of a future 100 km e+/e circular collider for precision studies and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 1035 cm–2 s–1. In order to reach these luminosity requirements, strong focusing is needed in the interaction regions. Large maximum beta values (of 7736 m for the Z energy) and the small beta star values, make the FCC-ee lattices particularly susceptible to misalignments and field errors. FCC-ee therefore presents an appreciable challenge for emittance tuning. In this paper, we describe a comprehensive correction strategy used for the low emittance tuning. The strategy includes programs that have been developed to optimise the lattice based on Dispersion Free Steering, linear coupling compensation based on Resonant Driving Terms and beta beat correction utilising response matrices. One hundred misalignment and field error random seeds were introduced in MAD-X simulations and the final corrected lattices are presented.

In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre-of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries.

The CERN Proton Synchrotron (PS) routinely crosses transition energy at around 6 GeV in order to accelerate protons that are injected in the Super Proton Synchrotron (SPS) or transferred to users of fixed target experiments. Depending on the beam parameters and intensity, a fast vertical coherent instability occurs during transition crossing. The instability, characterized by beam losses and a frequency spectrum in the range of 500--900 MHz, represents an important intensity limitation for the neutron time-of-flight (nTOF) beam, and in general could represent a bottleneck for future high intensity beams. In order to better understand the nature and the source of the instability and to find possible mitigations, a dedicated measurement campaign took place. Parallel to the measurements, beam dynamics simulations have been performed to study the observed instability. In particular, single bunch effects have been simulated using the PS transverse beam coupling impedance model developed over recent years. In this paper we present the measurements results along with the obtained instability thresholds. Different beam configurations and stabilizing effects, such as the gamma jump scheme and the octupole-induced tune spread, are also considered. The measurements results are compared with simulations.

K. Oide∗a, M. Aibab, S. Aumonc, M. Benediktc, A. Blondele, A. Bogomyagkovd , M. Boscolo f , H. Burkhardtc, Y. Caih, A. Doblhammerc, B. Haererc, B. Holzerc, J.M. Jowettc, I. Koopd , M. Koratzinose, E. Levichevd , L. Medinac, K. Ohmia, Y. Papaphilippouc, P. Piminovd , D. Shatilovd , S. Sinyatkin, M. Sullivanh, J. Wenningerc, U. Wienandsg, D. Zhoua and F. Zimmermannc E-mail:Katsunobu.Oide@kek.jp aKEK, Oho, Tsukuba, Ibaraki 305-0801, Japan bPSI 5232, Villigen PSI, Switzerland cCERN, CH-1211 Geneva 23, Switzerland dBINP SB RAS, Novosibirsk 630090, Russia eDPNC/Geneva University, CH-1211 Geneva 4, Switzerland f INFN/LNF, 00044 Frascati, Rome, Italy gANL, Argonne, Illinois 60439, U. S. A hSLAC, Menlo Park, California 94025, U. S. A.

A design of beam optics is made for the FCC-ee doublering e + e − collider. The main characteristics of the design are: 45 to 175 GeV beam energy, 100 km circumference withtwointeractionpoints(IPs)perring, horizontalcrossing angle of 30 mrad at the IP, and the crab-waist scheme with local chromaticity correction system. A so-called “tapering of the magnets is applied, which scales all fields of magnets with the local beam energy to compensate the synchrotron radiation (SR) loss along the ring. An asymmetric layout near the interaction region suppresses the critical energy of SR incoming to the detector at the IP below 100 keV, while matching the geometry to the beam line of the FCC proton collider (FCC-hh) [1] as close as possible. Sufficient transverse/longitudinal dynamic apertures (DAs) have been obtained to assure the beam lifetime with beamstrahlung and top-up injection. The synchrotron radiation loss in all magnets as well as the IP solenoids with compensation are taken into account.

Received 28 March 2017DOI:https://doi.org/10.1103/PhysRevAccelBeams.20.049901Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.© 2017 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBeam dynamicsBeam opticsNonlinear beam dynamicsSingle-particle dynamicsPhysical SystemsAccelerators & storage ringsHigh-energy accelerators & collidersParticle acceleratorsTechniquesLepton collidersAccelerators & Beams

A beam optics scheme has been designed for the future circular collider-e(+) e(-) (FCC-ee). The main characteristics of the design are: beam energy 45 to 175 GeV, 100 km circumference with two interaction points (IPs) per ring, horizontal crossing angle of 30 mrad at the IP and the crab-waist scheme [P. Raimondi, D. Shatilov, and M. Zobov, arXiv: physics/0702033; P. Raimondi, M. Zobov, and D. Shatilov, in Proceedings of the 22nd Particle Accelerator Conference, PAC-2007, Albuquerque, NM (IEEE, New York, 2007), p. TUPAN037.] with local chromaticity correction. The crab-waist scheme is implemented within the local chromaticity correction system without additional sextupoles, by reducing the strength of one of the two sextupoles for vertical chromatic correction at each side of the IP. So-called "tapering" of the magnets is applied, which scales all fields of the magnets according to the local beam energy to compensate for the effect of synchrotron radiation (SR) loss along the ring. An asymmetric layout near the interaction region reduces the critical energy of SR photons on the incoming side of the IP to values below 100 keV, while matching the geometry to the beam line of the FCC proton collider (FCC-hh) [A. Chance et al., Proceedings of IPAC'16, 9-13 May 2016, Busan, Korea, TUPMW020 (2016).] as closely as possible. Sufficient transverse/longitudinal dynamic aperture (DA) has been obtained, including major dynamical effects, to assure an adequate beam lifetime in the presence of beamstrahlung and top-up injection. In particular, a momentum acceptance larger than +/- 2% has been obtained, which is better than the momentum acceptance of typical collider rings by about a factor of 2. The effects of the detector solenoids including their compensation elements are taken into account as well as synchrotron radiation in all magnets. The optics presented in this paper is a step toward a full conceptual design for the collider. A number of issues have been identified for further study.

Long term beam loss are due to the presence of several factors, but lattice nonlinearities and high intensity certainly rank among the main causes for long term beam loss. Experimental and numerical studies have shown that periodic resonance crossing induced by space charge in a bunched beam is a deleterious effect for beam survival [1, 2]. Given the complexity of the topic, the studies in the past have been focused to investigate one dimensional resonances, for example in Ref. [1] the resonance was 4Qx = 25, while in Ref. [2] the resonance was 3Qx = 13. The underlying mechanism leading to beam loss is explained, in this case, in terms of instantaneous stable islands in a two-dimensional phase space and their crossing the particles orbits. This mechanism was studied in details in Ref. [3]. Studies for SIS100 have shown, however, that in the injection scenario of the uranium ions, random components of magnets nonlinearities excite a significant web of resonances including coupled resonances [4]. One of the simpler of the nonlinear coupled resonances is the Qx + 2Qy = N . Although the mechanism of the beam loss remains the same (the periodic resonance crossing induced by space charge), the details of the mechanism have never been, in this case, studied. The reason for that is in the complexity of the 4-dimensional coupled motion, which poses an extraordinary challenge to disentangle the dynamics. While for 1dimensional resonances the mechanism is relatively well understood, for 2-dimensional resonances it remains still unraveled. In this context, within the collaboration between CERN and GSI, in 2012 a new experimental campaign in the CERNPS for investigating the resonance Qx + 2Qy = 19 has been undertaken. The results of measurements collected in a scan of beam intensity/profiles versus tunes have shown puzzling features: when the space charge tune-spread overlaps the third order resonance an asymmetric beam response is found: in one plane we find halo, whereas in the other plane a core growth takes place. In Fig. 1 we show a plot with the beam profiles resulting from the space charge tune spread overlapping with the third order resonance, the tunes of the measurement are reported on the picture, the tune-shift is ∆Qx ' −0.046,∆Qy ' −0.068. The asymmetry of the profile is quite evident and shows that a new and more complex dynamics is driving the beam halo formation. The details of these measurements will be part of a dedicated article. The explanation of this beam profile shape have to be searched into the effects created by the 4D coupled dynamics. In this scenario the analogous of the fix points become the fix-lines [5]. These extended closed lines play a similar role as the fix points for the crossing of the 1D resonances. The description of this dynamics is beyond the purpose of this Figure 1: Beam profiles after 1 second storage of the beam in the CERN-PS. The asymmetry of the beam response is evident.

The FCC (Future Circular Collider) study represents a vision for the next large project in high energy physics, comprising an 80-100 km tunnel that can house a future 100 TeV hadron collider. The study also includes a high luminosity e+e- collider operating in the centre-of-mass energy range of 90-350 GeV as a possible intermediate step, the FCC-ee. The FCC-ee aims at definitive electro-weak precision measurements of the Z, W, H and top particles, and search for rare phenomena. Although FCC-ee is based on known technology, the goal performance in luminosity and energy calibration make it quite challenging. During 2014 the study went through an exploration phase. The study has now entered its second year and the aim is to produce a conceptual design report during the next three to four years. We here report on progress since the last IPAC conference.

A review of the status of the LHC injector beam studies related to the LHC Injectors Upgrade (LIU) project took place on the 28 August 2012 at CERN. The main goal of the review was to define work priorities for the rest of the run before the Long Shutdown 1 (LS1) and be able to: • specify the equipment to be built for the LIU project; • estimate achievable beam characteristics in the various accelerators. A team of external reviewers was also asked to participate in the event and comment on the status of the presently ongoing activities as well as give recommendations for future work.