The LHC machine configuration was changed in 2023 compared to previous years, requiring a new set of optics configurations to be measured and corrected. A telescopic optics was deployed in energy the ramp for the first time, which gave rise to a beta-beating of up to 25%. This was corrected using a global correction approach which reduced the beta-beat down to 10%. A change in the phase advance at injection was also applied to mitigate the negative effect of the main octupoles used to stabilize the beam. These measurements and corrections, coupled with the results from the 2024 commissioning, will be presented in this paper

A new layout for the energy-frontier hadron collider (FCC-hh) under study at CERN has been designed, following the constraints imposed by the outcome of recent tunnel placement studies. The new lattice and the need to maximize the dipole filling factor triggered a deep revision of the corrector systems located in the regular arcs, such as orbit, tune, linear coupling, and chromaticity correctors. The system of octupoles aimed at providing Landau damping has also been reviewed. Furthermore, the corrector package in the experimental insertion aimed at compensating the field quality of the triplet quadrupoles has been reconsidered in view of the experience gained with the design of the corresponding system developed for the CERN HL-LHC. In this paper, an account of this review is presented and discussed in detail. These estimates will need confirmation when the magnet design of the various correctors will be studied.

In this study, we reassess the dynamics within a simple accelerator lattice featuring a single degree of freedom and incorporating a sextupole magnet. In the initial segment, we revisit the H\'enon quadratic map, a representation of a general transformation with quadratic nonlinearity. In the subsequent section, we unveil that a conventional sextupole is essentially a composite structure, comprising an integrable McMillan sextupole and octupole, along with non-integrable corrections of higher orders. This fresh perspective sheds light on the fundamental nature of the sextupole magnet, providing a more nuanced understanding of its far-from-trivial chaotic dynamics. Importantly, it enables the description of driving terms of the second and third orders and introduces associated nonlinear Courant-Snyder invariant.

As part of the Diamond-II upgrade project*, the Diamond storage ring will be replaced with a new modified hybrid 6 bend achromat (M-H6BA) lattice, in which each existing arc sections will be split in two to provide additional mid-straights and thereby increase the ring capacity. The majority of insertion devices currently in operation will be either retained or upgraded, and the new mid-straights allow the total number of ID beamlines to be increased from 28 to 36. Therefore, it is important to investigate how the IDs will affect the equilibrium emittance and energy spread, along with their impact on the linear and nonlinear beam dynamics. Methods to compensate for their effects have been established, including a re-optimization of the octupole settings and identification of alternative working points. A kickmap approach has been used to model all IDs, including the APPLE-II IDs and APPLE-II-Knot with active shim wires. In this paper, the outcome of these investigations will be presented and discussed.

Brookhaven National Laboratory (BNL) was recently chosen to host the Electron Ion Collider (EIC), which will collide high energy and highly polarized hadron and electron beams with a center of mass energy up to 140 GeV and a luminosity of up to 1e+34 1/cm^2/s. Part of the accelerator complex is a Rapid Cycling Synchrotron (RCS), which is planned to accelerate electrons from 400 MeV to 18 GeV. Due to the large energy range and the given circumference of the ring, the magnetic fields of the RCS magnets at injection are very low (~mT). A test dipole magnet was constructed to study differences in field quality from 5-50 mT. The paper discusses the design of the test magnet and first measurement results.

The ESRF-EBS injection is performed with a standard off-axis injection scheme consisting of two in-air septa S1/2, one in vacuum septum S3 and four kicker magnets K1 to K4 to generate the injection bump. We can achieve 80% efficiency with this scheme. Despite many modifications and adjustments which allow the reduction of the perturbation, some beamlines are still affected. The Non-Linear Kicker could be a solution to this problem because it acts only on the injected beam. This paper reports on the magnetic design of the Non-Linear Kicker, including the octupole like Magnetic field simulations, magnetic forces calculations and mechanical tolerance optimizations.

Schottky monitors are valuable non-invasive tools used for beam diagnostics, providing insights into crucial bunch characteristics such as tune, chromaticity, bunch profile, or synchrotron frequency distribution. This study investigates Schottky spectra at the Large Hadron Collider (LHC) through a combination of simulations and measurements. Experimental data from lead ion bunches are compared with simulated spectra derived from time-domain, macro-particle simulations. In particular, amplitude detuning due to the octupole magnets, known to influence the Schottky spectra, is incorporated into the simulations. These simulations are performed for various octupoles currents with the goal of better understanding the interplay between octupoles and the Schottky spectrum. Finally, measured spectra are compared to simulations performed using the best available knowledge of the parameters impacting the spectra.

Schottky monitors serve as non-invasive tools for beam diagnostics, providing insights into crucial bunch characteristics such as tune, chromaticity, bunch profile, or synchrotron frequency distribution. However, octupole magnets commonly used in circular storage rings to mitigate instabilities through the Landau damping mechanism, can significantly affect the Schottky spectrum. Due to the amplitude-dependent incoherent tune shift of individual particles, the satellites of the Schottky spectrum are smeared out as the octupolar field increases. This study investigates the impact of octupoles and their incorporation into theory, with the goal of improving beam and machine parameter evaluation from measured spectra. Theoretical findings are validated through macro-particle simulations conducted across a range of octupole strengths, encompassing typical operational conditions at the Large Hadron Collider.

Nonlinear focusing elements can enhance the stability of particle beams in high-energy colliders through Landau Damping, by means of the tune spread which is introduced. Here we discuss an experiment at Fermilab's Integrable Optics Test Accelerator (IOTA) which investigates the influence of nonlinear focusing elements, such as octupoles, on the beam’s transverse stability. In this experiment, we employ an anti-damper, an active transverse feedback system, as a controlled mechanism to induce coherent beam instability. By utilizing the anti-damper we can examine the impact of a nonlinear focusing element on the beam's transverse stability. The stability diagram, a tool used to determine the system's stability, is measured using a recently demonstrated method at the LHC. The experiment at IOTA adds insight towards this stability diagram measurement method by supplying a reduced machine impedance to investigate the machine impedance’s effect on the stability diagram, as well as by aiming to map out the full stability diagram by using a large phase range of the anti-damper. From this experiment in IOTA, we present the first results of stability diagram analysis with varying octupole currents.

The Resonance Island Jump (RIJ) scheme for transition crossing in the Hadron Storage Ring of the Electron-Ion Collider is radically new, and untested. Beam experiments in RHIC will be necessary if it becomes necessary to consider the RIJ scheme as a serious alternative to upgrading the first order linear jump scheme currently implemented in RHIC. This paper outlines the theoretical foundations of the RIJ scheme, and considers how a beam experiment in RHIC could be performed.

Optimizing the configuration of an operational cycle of a collider such as the LHC is a complex process, requiring various simulation studies. In particular, Dynamic Aperture (DA) simulations, based on particle tracking, serve as indispensable tools for achieving this goal. In the framework of the high-luminosity LHC (HL-LHC) studies, our primary focus lies in performing parametric beam-beam DA simulations for the critical phases of the collision process, which includes the collapse of the beam separation bump, as well as the start, and the end of the luminosity leveling. In this paper, we present the status of our ongoing studies for different optics and filling schemes, and we comment on how they could guide the orchestration of the operational settings along the luminosity leveling phase of the HL-LHC cycle.

In contemporary radiotherapy, most accelerators employ the scatter technique to achieve a relatively uniform dose distribution of electron beams. However, this method often results in the loss of a substantial number of particles, leading to suboptimal efficiency. This paper proposes a method utilizing permanent magnet components to homogenize the beam, achieving both beam spreading and uniformity within a short distance without particle loss. The proposed homogenization beamline comprises two quadrupole magnets and two octupole magnets, ultimately yielding a square field with a side length of approximately 20 cm. The manuscript includes theoretical derivations and simulation validations, with the physical prototype currently under fabrication. Experimental results will be provided in future work.