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One of the major upcoming challenges in particle physics is achieving precise measurements of the Z, W, and H bosons, as well as the top quark. To meet these targets, the next e\textsuperscript{+}e\textsuperscript{-} collider complex, FCC-ee, will need to achieve unprecedented luminosities. The FCC-IS European Study is investigating the feasibility of these challenges, with a cornerstone of the study being the design and optimization of the high-energy booster (HEB). This paper provides an update on the status of the HEB of FCC-ee in light of recent developments in the injector and collider survey, as well as an overview of ongoing work on longitudinal stability and design robustness in relation to field, alignment, and diagnostics errors. Constraints and effects related to the design frequency of the accelerating cavities, as well as collective effects, are also highlighted. Lastly, the paper presents an investigation into an alternative arcs cell design., Comment: pre-print of ICFA Newsletter 2023

The design of the optics of a full length 6 GeV booster for the USSR (Ultimate Source of Synchrotron Radiation) are presented. This option already followed with success by other laboratories, would allow to obtain a small emittance injected beam thus enabling smooth top-up operation. Details of the design inspired by the ESRF DBA lattice and the possible operating modes are described. The transfer lines booster to storage ring are also addressed in this paper., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

DAΦNE, the Frascati lepton collider, has completed the preparatory phase in order to deliver luminosity to the SIDDHARTA-2 detector. DAΦNE colliding rings rely on a new interaction region, which implements the well-established Crab-Waist collision scheme, and includes a low-beta section equipped with newly designed permanent magnet quadrupoles, and vacuum components. Diagnostics tools have been improved, especially the ones used to keep under control the beam-beam interaction. The horizontal feedback in the positron ring has been potentiated in order to achieve a higher positron current. Luminosity diagnostics have been also updated so to be compatible with the new detector design. The commissioning was initially focused on recovering the optimal dynamical vacuum conditions, outlining alignment errors, and optimizing ring optics. For this reason, a detuned optics, featured by relaxed low-b condition at the interaction point and Crab-Waist Sestupoles off, has been applied. In a second stage a low-b optics has been implemented to test collisions with a preliminary setup of the experiment detector. Machine preparation and the first luminosity results are presented and discussed., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The SOLEIL storage ring upgrade will require an injected beam with small transverse and longitudinal sizes. To meet this requirement, the present booster also needs to be upgraded, aiming to reduce the emittance below 10 nm·rad. A multi-bend achromat lattice is designed in this context for the booster upgrade, which consists of two superperiods to respect the present race-track configuration. The lattice is a 16BA HOA (Higher-Order Achromat) type lattice, composed of 14 unit cells, 2 matching cells and a long straight section, and combined-function bending magnets are used in the unit cells to both save space and reduce the emittance. The natural emittance of the designed booster is 5.2 nm·rad at the final energy of 2.75 GeV. This paper presents the general constraints, linear lattice design and nonlinear dynamics optimization for the booster upgrade., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The ESRF operates a 6 GeV 4th generation light source, the ESRF-EBS. This storage ring is the first to implement the Hybrid Multi-Bend Achromat lattice (HMBA). The HMBA lattice provides a reduction of the horizontal emittance of approximately a factor 30 with respect to the former Double Bend Achromat (DBA) structure, considerably improving the brilliance and transverse coherence of the ESRF accelerator complex while maintaining large horizontal acceptance and excellent lifetime performance. In this report, the characteristics of the HMBA lattice will be reviewed and the beam commissioning results and first operation experience of the new ESRF storage ring will be presented., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The main goal of the Accelerator Test Facility 2 (ATF2) is to demonstrate the feasibility of future linear colliders’ final focus systems. The Ultra-low β^{*} optics of ATF2 is designed to have the same chromaticity level as CLIC. To ease the tuning procedure, a pair of octupoles was installed in ATF2 in 2017. This paper reports the optimizations performed to the octupoles’ setup for Ultra-low β^{*} optics including the new alignment technique, based on the waist shift and the new tunning knobs constructed for this optics. The full tuning procedure including the static errors is simulated for this setup., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The Compact Linear Collider (CLIC) could provide e⁺e⁻ collisions in two detectors simultaneously possibly at a repetition frequency twice the design value. In this paper, a novel dual Beam Delivery System (BDS) design is presented including optics designs and the evaluation of luminosity performance with synchrotron radiation (SR) and solenoid effects for both energy stages of CLIC, 380 GeV and 3 TeV. In order to develop the novel optics design, parameters such as the longitudinal and the transverse detector separations were optimized. The luminosity performance of the novel CLIC scheme was evaluated by comparing the different BDS designs for both energy stages of CLIC. The dual CLIC BDS design provides a good luminosity and proves to be a viable candidate for future linear collider projects., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

International audience; The Compact Linear Collider (CLIC) could provide $e^+e^−$ collisions in two detectors simultaneously possibly at a bunch train frequency in the linac twice the baseline design value. In this paper, a novel dual beam delivery system (BDS) design is presented in order to serve two interaction regions (IR1 and IR2) including optics designs and the evaluation of luminosity performance with synchrotron radiation (SR) and solenoid effects for both energy stages of CLIC, 380 GeV and 3 TeV. IR2 features a larger crossing angle than the current baseline. The luminosity performance of the novel CLIC scheme was evaluated by comparing the different BDS designs with and without the detector solenoid field effects. It has to be highlighted that the impact of the detector solenoid on luminosity had not been evaluated for the current CLIC baseline, which amounts to a loss of about 4% that corresponds to the same value of the old baseline design. At 380 GeV the novel dual BDS design features same luminosities than the current baseline. However at 3 TeV the luminosity performance is reduced by 2% from the baseline design for the IR1 and by 33% for the IR2. The dual CLIC BDS design provides adequate luminosities to two detectors and proves to be a viable candidate for future linear collider projects.

The first stage of the Compact Linear Collider (CLIC) is planned to be at the center-of-mass energy of 380 GeV. The final focus system (FFS) was re-optimized for this energy and for L* of 6 m (distance between the Interaction Point (IP) and the last quadrupole, QD0). Furthermore, the FFS optics was optimized for the vertical beta-function of 70 microns to approach the Hourglass effect limit. This paper reports the exploration of shortening the Final Doublet (FD) within the FFS to reduce the chromaticity. In addition, an alternative optics design is investigated with a different dispersion profile along the FFS, which outperforms the previous optics with the same β^{*}, increasing luminosity by 5 %., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

For future linear colliders, a nanometer-scale beam size at the interaction point (IP) is one of the most challenging technical aspects. To explore the feasibility of a final focus system with a high chromaticity level, comparable to that of the Compact Linear Collider, the ultralow ${\ensuremath{\beta}}^{*}$ optics has been proposed and tuned at the KEK Accelerator Test Facility 2. In this paper, the recent experimental results are presented, which demonstrate the capability of achieving and stabilizing a vertical average beam size of 60 nm and below at the virtual IP. The observed vertical beam size is about 20 nm above the numerical predictions in the presence of static and dynamic imperfections. We interpret this discrepancy as beam size growth due to multipole fields, beam jitters and wakefield effects, and diagnostic errors.

The design of a future multi-TeV muon collider needs new ideas to overcome the technological challenges related to muon production, cooling, accumulation and acceleration. In this paper a layout of a positron driven muon source known as the Low EMittance Muon Accelerator (LEMMA) concept is presented. The positron beam, stored in a ring with high energy acceptance and low emittance, is extracted and driven to a multi-target system, to produce muon pairs at threshold. This solution alleviates the issues related to the power deposited and the integrated Peak Energy Density Deposition (PEDD) on the targets. Muons produced in the multi-target system will then be accumulated before acceleration and injection in the collider. A multi-target line lattice has been designed to cope with the focusing of both the positron and muon beams. Studies on the number, material and thickness of the targets have been carried out. A general layout of the overall scheme and a description is presented, as well as plans for future R&D., 18 pages, 32 figures

Accelerator physics needs advanced modeling and simulation techniques, in particular for beam stability studies. A deeper understanding of the effects of magnetic fields non-linearities will greatly help in the improvement of future colliders design and performance. In *, a new tracking method was proposed to study the effect of the longitudinal dependency of the harmonics on the beam dynamics. In this paper, the study will focus on the effects on observable quantities in beam based measurements, for the case of HL-LHC Inner Triplet and with possible tests in LHC., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

PERLE (Powerful ERL for Experiments) is a novel ERL test facility, initially proposed to validate choices for a 60 GeV ERL foreseen in the design of the LHeC and the FCC-eh. Its main thrust is to probe high current, CW, multi-pass operation with superconducting cavities at 802 MHz (and perhaps testing other frequencies of interest). With very high virtual beam power (~ 10 MW), PERLE offers an opportunity for controllable study of every beam dynamic effect of interest in the next generation of ERL design; becoming a ‘stepping stone' between present state-of-art 1 MW ERLs and future 100 MW scale applications. PERLE design features Flexible Momentum Compaction lattice architecture for six vertically stacked return arcs and a high-current, 6 MeV, photo-injector. With only one pair of 4 cavity cryomodules, 400 MeV beam energy can be reached in 3 re-circulation passes, with beam currents in excess of 15 mA. The beam is decelerated in 3 consecutive passes back to the injection energy, transferring virtually stored energy back to the RF. This unique facility will serve as a test-bed for high current ERL technologies, as well as a user facility in low energy electron and photon physics., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

International audience; Aiming to simplify the machine detector interface of the Compact Linear Collider (CLIC), a new detector model has been designed allowing the last quadrupole QD0 of the final focus system (FFS) to be located outside of the experiment with a distance L* from the interaction point of 6 m. In this paper, the beam delivery system (BDS) has been reoptimized, offering a luminosity performance that exceeds the design requirements by 11% for the total luminosity and by 7% in the energy peak. A simulation campaign has been carried out and has proved the feasibility of recovering the luminosity under realistic transverse misalignments of the FFS optics, by means of different orbit and aberration correction techniques, making this long L* design a realistic candidate for the future CLIC BDS.

The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the three options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group. The layout of FCC-hh has been optimized to a more compact design following recommendations from civil engineering aspects. The updates on the first order and second order optics of the ring will be shown for collisions at the required centre-of-mass energy of 100 TeV. Special emphasis is put on the dispersion suppressors and general beam cleaning sections as well as first considerations of injection and extraction sections., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

A head-on beam-beam compensation scheme was implemented for operation in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The compensation consists of a lattice for the minimization of beam-beam driven resonance driving terms, and electron lenses for the reduction of the beam-beam induced tune spread. We describe the implementations of the lattice and electron lenses, and report on measurements of lattice properties and the effect of the electron lenses on the hadron beam., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

International audience; A head-on beam-beam compensation scheme was implemented for operation in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory [Phys. Rev. Lett. 115, 264801 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.264801]. The compensation consists of electron lenses for the reduction of the beam-beam induced tune spread, and a lattice for the minimization of beam-beam generated resonance driving terms. We describe the implementations of the lattice and electron lenses, and report on measurements of lattice properties and the effect of the electron lenses on the hadron beam.

International audience; A long list of optics and beam dynamics challenges for pp colliders includes the following: design of the interaction region with a low beta function; beam-beam effects; impedance, HOM losses and instabilities; achieving the dynamic aperture required for adequate beam lifetime, comprising the optimization of the arc optics; emittance control, including alignment and field errors, lattice nonlinearities, as well as beam-beam effects; machine protection, with dedicated halo cleaning section; injection and extraction of the beam. The lattice design has to handle these different challenges; the optimization is then multi-criteria like the machine performance or the machine cost. We will then consider here a few aspects of the lattice design like the arc optimization, some insertions like the interaction region or the beam cleaning insertions and how to tune the different regions together. To illustrate the problematics, we will use some examples coming from LHC [1], HL-LHC [2] or FCC-hh [3].

10 pp. (2006)., For the second bunch compressor chicane at CLIC a maximum emittance growth of only 5% in the horizontal plane is allowed. The emittance growth is the conse- quence of incoherent and coherent synchrotron radiation emitted by the electrons along the chicane. Both effects are reviewed and various chicanes are compared in computer simulations. A chicane layout is found which preserves the emittance well within the specifications.