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The Super Tau-Charm Facility (STCF) is a proposed dual-ring electron–positron collider in China, designed to operate at a center-of-mass energy (CME) range of 2–7GeV with symmetric beam energies. The collider aims for a luminosity exceeding 5×1034cm−2s−1 at the beam energy of 2.0GeV. This work presents the preliminary lattice design for the STCF collider ring, specifically optimized for the 2.0GeV beam energy. To improve the nonlinear dynamics performance, the optimization of lattice is carried out by adjusting the strengths of sextupole and octupole magnets following the tuning of phase advances. [ABSTRACT FROM AUTHOR]

A multi-objective genetic algorithm (MOGA) is a powerful global optimization tool, but its results are considerably affected by the crossover parameter ηc. Finding an appropriate ηc demands too much computing time because MOGA needs be run several times in order to find a good ηc. In this paper, a self-adaptive crossover parameter is introduced in a strategy to adopt a new ηc for every generation while running MOGA. This new scheme has also been adopted for a multi-generation Gaussian process optimization (MGGPO) when producing trial solutions. Compared with the existing MGGPO and MOGA, the MGGPO and MOGA with the new strategy show better performance in nonlinear optimization for the design of low-emittance storage rings.

A multi‐objective genetic algorithm (MOGA) is a powerful global optimization tool, but its results are considerably affected by the crossover parameter ηc. Finding an appropriate ηc demands too much computing time because MOGA needs be run several times in order to find a good ηc. In this paper, a self‐adaptive crossover parameter is introduced in a strategy to adopt a new ηc for every generation while running MOGA. This new scheme has also been adopted for a multi‐generation Gaussian process optimization (MGGPO) when producing trial solutions. Compared with the existing MGGPO and MOGA, the MGGPO and MOGA with the new strategy show better performance in nonlinear optimization for the design of low‐emittance storage rings. [ABSTRACT FROM AUTHOR]

The heavy ion facility for technological applications is developed at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences. The booster synchrotron with electron cooling is one of the main parts of the facility. This work presents the beam dynamics simulation with betatron coupling and nonlinearities of the guided magnetic field. The transverse betatron coupling excited by electron cooling solenoid was compensated by the pair of skew quadrupole triplets with antisymmetric supply and located symmetrically relative to the solenoid center. The calculation of the vertical dispersion excited by the magnetic field of toroidal sections of the electron cooler was performed. The accelerator lattice was optimized for minimization of vertical dispersion. Another important factor of the beam dynamics is the tune dependence versus momentum deviation called chromaticity. To correct chromaticity, sextupole magnets are applied. On the other hand, sextupoles excite nonlinear resonances that can lead to significant limitation of the dynamic aperture. The dynamic aperture of the synchrotron was simulated by scanning of horizontal and vertical tunes in conditions of chromaticity and betatron coupling suppression. This method makes it possible to identify dangerous resonances. According to the calculations presented, a scheme with application of six sextupole families are developed. This scheme makes it possible to significantly reduce the influence of most dangerous resonances. The wide area of tunes with a fairly large dynamic aperture for particles with required momentum spread was found in simulations. Selection of the operating point in this particular area makes it possible to reduce the space charge effect on the dynamic aperture. At the chosen operating point, the influence of eddy currents and magnetic fields nonlinearities on the dynamic aperture was investigated. [ABSTRACT FROM AUTHOR]

The CEPC booster needs to provide electron and positron beams to the collider at different energy with required injection efficiency. At Higgs energy, only the on-axis injection from booster to collider can be fulfilled in CDR. With a consideration of keeping the off-axis injection scheme for safety and reliability, a new booster design based on TME lattice is considered to reduce the emittance by three times after CDR. The new booster design has reached an emittance of 1.3 nm at 120 GeV and the DA without errors is even better than CDR. The geometry of new booster is designed carefully in order to share the same tunnel with collider. The design status of CEPC new booster including parameters, optics, dynamic aperture and geometry is discussed in this paper. [ABSTRACT FROM AUTHOR]

A compact pencil beam scanning (PBS) proton therapy system, Mevion S250i with Hyperscan, is equipped with adaptive aperture (AA) to collimate the beam with 2 different techniques: Static aperture (SA) and dynamic aperture (DA). SA (single aperture) collimates the outermost contour of the target and DA (multi-layer aperture) collimates each energy layer of the proton beam. This study evaluates dosimetric performance of SA and DA for different disease sites. This study includes 5 disease sites (brain, head and neck (HN), partial breast, lung, and prostate), and 8 patients for each. A total of 80 patient treatment plans (5 sites × 8 patients per site × 2 collimation techniques) were created using 2 to 4 proton beams. Both SA and DA plans were made using the same plan and optimization parameters calculated by a Monte Carlo dose algorithm. Multi-field optimization (MFO) was used for HN treatment plans, whereas treatment plans for the other sites were made with single-field optimization (SFO). All plans were robustly optimized with 3 mm (brain and HN) or 5 mm (breast, lung, and prostate) position uncertainty along with 3.5% range uncertainty. Treatment plans were normalized such that 99% of the clinical target volume (CTV) received 100% of the prescribed dose. Dose volume histogram (DVH) parameters were evaluated for CTV and organs at risk (OARs). The CTV was also evaluated for dose homogeneity, dose conformity, and dose gradient. In general, the DA plan made CTV hotter, while it saved OARs better. DA produced better conformity with sharper dose falloff around CTV, while SA generated better homogenous target coverage. DA decreased D max to brainstem (1.2% = [(SA-DA)/DA × 100%]) for brain, D max to the spinal cord (137.3%) for HN, D 1% of the ipsilateral lung (50.5%) for breast, and D max to the spinal cord (74.0%) for lung. The dose reduction in bladder and rectum for prostate plans with DA was less than 2.5%. The DA plans reduced the dose to OARs for all disease sites but escalated the target maximum dose for the same target coverage than the SA plans. The OAR saving and dose escalation depended on CTV size, proximity of the OARs to CTV, and the plan complexity. [ABSTRACT FROM AUTHOR]

The CEPC booster has been designed to provide electron and positron beams at different energies for the collider. The latest booster design aligns with the TDR's higher luminosity objectives for four energy modes. The booster's optics have transitioned from FODO in the CDR to TME structure, resulting in a significant reduction in emittance to match the lower emittance of the collider in the TDR. Extensive efforts have been invested to address the challenge of error sensitivity for the booster, ensuring that the dynamic aperture with errors meets the requirements across all energy modes. Additionally, a combined magnets scheme (B + S) has been proposed to minimize the magnet construction costs and reduce the operation costs through lower power consumption. This paper discusses the design status of the CEPC booster in the TDR, encompassing parameters, optics, dynamic aperture, ramping scheme, and injection scheme. [ABSTRACT FROM AUTHOR]

For any storage ring-based large-scale scientific facility, one of the most important performance parameters is the dynamic aperture (DA), which measures the motion stability of charged particles in a global manner. To date, long-term tracking-based simulation is regarded as the most reliable method to calculate DA. However, numerical tracking may become a significant issue, especially when a plethora of candidate designs of a storage ring need to be evaluated. In this paper, we present a novel machine learning-based method, which can reduce the computation cost of DA tracking by approximately one order of magnitude, while keeping sufficiently high evaluation accuracy. Moreover, we demonstrate that this method is independent of concrete physical models of a storage ring. This method has the potential to be applied to similar problems of identifying irregular motions in other complex dynamical systems.

In the tracking of the future circular Higgs factories, significant reduction of dynamic aperture due to the synchrotron radiation has been observed. This paper will analyze the synchrotron radiation effects including the closed orbit and optics distortion, radiation damping and quantum excitation for the lattice of CEPC. [ABSTRACT FROM AUTHOR]

A new NICA collider lattice with the symmetric arrangement of triplets at the interaction points and a shifted working point (Qx,y ∼ 9.1) is proposed and calculated. This lattice involves two rings (ring A and ring B) with a superperiodicity of 2 and different optics. It is shown that, while maintaining the nominal beta function at the interaction points (βx,y= 0.35 m) with allowance for all perturbing factors, the new lattice allows DA ∼ 75 mm to be obtained in both rings, which is considerably larger than the collider chamber acceptance (ACC = 40 mm mrad). [ABSTRACT FROM AUTHOR]

A Machine Learning approach to scientific problems has been in use in Science and Engineering for decades. High-energy physics provided a natural domain of application of Machine Learning, profiting from these powerful tools for the advanced analysis of data from particle colliders. However, Machine Learning has been applied to Accelerator Physics only recently, with several laboratories worldwide deploying intense efforts in this domain. At CERN, Machine Learning techniques have been applied to beam dynamics studies related to the Large Hadron Collider and its luminosity upgrade, in domains including beam measurements and machine performance optimization. In this paper, the recent applications of Machine Learning to the analyses of numerical simulations of nonlinear beam dynamics are presented and discussed in detail. The key concept of dynamic aperture provides a number of topics that have been selected to probe Machine Learning. Indeed, the research presented here aims to devise efficient algorithms to identify outliers and to improve the quality of the fitted models expressing the time evolution of the dynamic aperture.

Abstract In recent years, modelling the evolution of beam losses in circular proton machines starting from the concept of dynamic aperture its time evolution has been the focus of intense research. Results from single-particle non-linear beam dynamics have been used to build simple models that proved to be in good agreement with beam measurements. These results have been generalised, thus opening the possibility to describe also the luminosity evolution in a circular hadron collider. In a companion paper Giovannozzi and Van der Veken (0000), the derivation of a scaling law for luminosity, which includes both burn off and pseudo-diffusive effects, has been carried out. In this paper, the proposed models are applied to the analysis of the data collected during the CERN Large Hadron Collider (LHC) Run 1. A dataset referring to the proton physics runs for the years 2011 and 2012 has been analysed and the results are proposed and discussed in detail in this paper. [ABSTRACT FROM AUTHOR]

Abstract In recent years, modelling the evolution of beam losses in circular proton machines starting from the evolution of the dynamic aperture has been the focus of intense research. Results from single-particle, non-linear beam dynamics have been used to build simple models that proved to be in good agreement with beam measurements. These results have been generalised, thus opening the possibility to describe also the luminosity evolution in a circular hadron collider. In this paper, the focus is on the derivation of scaling laws for luminosity, which include both burn off and additional pseudo-diffusive effects. It is worthwhile stressing that time-dependence of some beam parameters can be taken into account in the proposed framework. The proposed models are applied to the analysis of a subset of the data collected during the CERN Large Hadron Collider (LHC) Run 1 in a companion paper (Giovannozzi and Van der Veken, 2018). [ABSTRACT FROM AUTHOR]

In September 2012, Chinese scientists proposed a Circular Electron Positron Collider (CEPC) in China at 240 GeV center-of-mass energy for Higgs studies. The booster provides 120 GeV electron and positron beams to the CEPC collider for top-up injection at 0.1 Hz. The design of the full energy booster ring of the CEPC is a challenge. The ejected beam energy is 120 GeV and the injected beam energy is 6 GeV. In this paper we describe two alternative schemes, the wiggler bend scheme and the normal bend scheme. For the wiggler bend scheme, we propose to operate the booster ring as a large wiggler at low energy and as a normal ring at high energy to avoid the problem of very low dipole magnet fields. For the normal bend scheme, we implement the orbit correction to correct the earth field. [ABSTRACT FROM AUTHOR]

In this paper, we introduced the parameter choice and the first version lattice design for a 61 km and 100-km Super Proton-Proton Collider (SPPC). We started the lattice design and the beam dynamics study from last year and showed the preliminary dynamic aperture result of these two SPPC lattice versions. We also showed the layout, the lattice design and the dynamic aperture study of a CEPC partial double ring, an advanced partial double ring and a fully partial double ring schemes. [ABSTRACT FROM AUTHOR]

In an ultrasound imaging system, dynamic focusing is crucial in improving the spatial resolution and signal-to-noise ratio. However, the generation of focusing delay data (FDD) requires complex calculations and a large amount of memory. The dynamic focusing system may become extremely complex as the number of focusing channels and the focal depth increase. This paper presents a simplified scheme of a high-precision generator for the FDD in Field-programmable Gate Array (FPGA). First, the original FDD are pre-calculated, quantized, decomposed, and compressed by exploiting the recursive characteristics between focusing channels. Then, the initial value and changing locations of each channel are stored as a reference data set. Finally, the FDD are generated in real time by decompressing the preloaded reference data set during the focusing process. The results indicate that the proposed approach consumes less than l% of the memory space of the original method, which may provide significant resource savings and low hardware power consumption. The proposed method can also be applied to convex or flat transducers array in compact beamformers. Moreover, the focusing accuracy and compression ratio can be flexibly adjusted, and the compression ratio can be further improved when the proposed approach is combined with the dynamic aperture. The proposed approach is contribute to the solution of the problem of the complex and large amount of data in ultrasonic imaging system. It is suitable for designing a specific compact focusing beamformer, particularly for a portable ultrasound imaging system. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a lattice design for an ultra-low emittance storage ring with intermediate energy of 3 GeV and circumference of 576 m. We present the design results for a seven-band achromat lattice with the natural emittance of 90 pm-rad. The base line is based on 20 straight sections with the length of 6 m. The minimum distance between different magnets is 10 cm and it has been tried to keep the lattice structure as simple as possible. The brilliance of radiated synchrotron radiation from a 2.24 m In-vacuum undulator installed in the lattice is 4 × 10 21 photons ∕ s mm 2 mm 2 mrad 2 0 . 1 % BW . We will address the challenging points of designed ultra-low emittance storage ring lattice such as strong nonlinearity and collective effects. The dynamic aperture of the lattice is comparatively sufficient for off-axis injection and the lifetime is relatively large without using any harmonic cavity. Since the proposed lattice structure in some aspects is similar to MAX IV storage ring, we will make some comparison between two lattices in different sections. [ABSTRACT FROM AUTHOR]

This paper proposed a novel algorithm to suppress the deception jamming against the single channel synthetic aperture radar (SAR), which provides an effective and economic way to improve the anti-deception-jamming ability of the conventional SAR system. The dynamic apertures are employed to provide multiple observations about the time-frequency distributions of the deception jamming and real echoes. The amplitude loss in different dynamic apertures is modeled to formulate the optimization problem for deception jamming suppressing. Super-resolution scheme is also involved to tighten the feasible region of the problem. The effectiveness of the proposed algorithm is verified by simulation. [ABSTRACT FROM PUBLISHER]

In-vacuum undulators are the most important devices for a third-generation light source such as the Taiwan Photon Source. Magnetic arrays of these undulators are designed to minimize the transverse field roll-off which can decrease the dynamic aperture, the lifetime of the electron beam, and the efficiency of injection. Manufacturing errors in the magnet block and pole dimensions, errors of deformation and assembly, and imperfections of design make the transverse magnetic-field roll-off worse and the peak field strength less than designed. These imperfections and errors are inevitable but can be decreased during fabrication. Simulations and experiments have been performed to assess their influences on field performance and to generate schemes for improvement. The experimental setups, simulation models, and results are described in detail in this letter. [ABSTRACT FROM PUBLISHER]

Top-up operation requires high efficiency injection with insertion devices at small gaps. We present a case study of one elliptically polarizing undulator at the Canadian Light Source that unexpectedly began having a detrimental impact on injection efficiency after operating for many years without issue. By performing beam-based measurements in the storage ring and magnetic measurements in our magnetic measurement laboratory, we built a model that provided an explanation and a remedy. An unrelated change in the vertical limiting physical aperture coupled to an octupole resonance caused a loss of dynamic aperture that explained the decreased injection efficiency. The remedy was to change the on-axis tunes of the storage ring, avoiding the resonance. We hope this detailed and thorough case study may help other laboratories to maintain high injection efficiency while requiring a minimum of restrictions on insertion device operating ranges. [ABSTRACT FROM AUTHOR]

We report an efficient dynamic aperture (DA) optimization approach using multi-objective genetic algorithm (MOGA), which is driven by nonlinear driving terms computation. It was found that having small low order driving terms is a necessary but insufficient condition of having a decent DA. Then direct DA tracking simulation is implemented among the last generation candidates to select the best solutions. The approach was demonstrated successfully in optimizing NSLS-II storage ring DA. [ABSTRACT FROM AUTHOR]

In this paper, we introduce the layout and lattice design of Circular-Electron-Positron-Collider (CEPC) partial double ring scheme and the lattice design of Super-Proton-Proton-Collider (SPPC). The baseline design of CEPC is a single beam-pipe electron positron collider, which has to adopt pretzel orbit scheme and it is not suitable to serve as a high luminosity factory. If we choose partial double ring scheme, we can get a higher luminosity with lower power and be suitable to serve as a high luminosity factory. In this paper, we discuss the details of CEPC partial double ring lattice design and show the dynamic aperture study and optimization. We also show the first version of SPPC lattice although it needs lots of work to do and to be optimized. [ABSTRACT FROM AUTHOR]

Setting up collisions in high energy circular colliders requires beam acceleration and “beta-squeeze”. The latter produces small beam sizes, and hence, high luminosity by applying strong focusing with quadrupoles near the interaction points. At the Relativistic Heavy Ion Collider (RHIC), these two processes, beam acceleration and beta-squeeze, have been performed simultaneously during recent years. In the past, beam optics correction at RHIC has only taken place at injection and at final energy, with interpolation of corrections partially into the acceleration cycle. Recent measurements of the beam optics during acceleration and squeeze have evidenced significant beta-beats that, if corrected, could minimize undesirable emittance dilutions and maximize the spin polarization of polarized proton beams by avoiding the high-order multipole fields sampled by particles within the bunch. We recently demonstrated beam optics corrections during acceleration at RHIC. As a valuable by-product, these corrections minimized the beta-beat at the profile monitors, so providing more accurate measurements of the evolution of the beam emittances during acceleration. [ABSTRACT FROM AUTHOR]

We present a lattice design for a low-emittance and high-brilliance 3 GeV synchrotron light source that has been widely investigated in the world. We show the design results for a MBA (Multi-Bend Achromat) lattice with an emittance of 1.3 nm and 282.4 m circumference. Each cell has 5 bending magnets that consist of outer two with bending angle of 4.5° and inner three with bending angle of 7°. The lattice is designed to be flexible and consists of 12 straight sections in which one straight section has a length of 5.9 m. We have studied the dynamic aperture in the lattice with machine errors. It is shown that the designed low-emittance lattice provides sufficient dynamic aperture after COD correction. We present the results of variations of emittance, energy spread and dynamic aperture due to in-vacuum undulators in the straight sections. We performed particle tracking after the beam injection to investigate the efficiency of the injection scheme. We show the designed results of an injection scheme that shows the space allocation in injection section and the particle motions of injected beam. Our designed lattice provides a good optimization in terms of the emittance and brilliance as a light source for 3 GeV energy and circumference of 28 m. [ABSTRACT FROM AUTHOR]

We investigate the Fraunhofer diffraction of a Laguerre-Gaussian (LG) beam incident on a dynamic superposed dual-triangular aperture. The evolution of the diffraction pattern from this aperture is analyzed experimentally and theoretically. A special aperture, called the hex-star triangular aperture, demonstrates interesting diffraction patterns. Further, the diffraction properties of integer, half-integer, and fractional orders of topological charges at the Fraunhofer zone are studied by using the hex-star triangular aperture. This study can provide additional information to enhance the understanding of the diffraction properties of the LG beam transmitted through a complex aperture. [ABSTRACT FROM AUTHOR]