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Beam position monitors (BPMs) are widely used for beam diagnostics in particle accelerators. Turn-by-turn (TbT) beam centroid data provide a means to estimate performance-critical accelerator parameters, like betatron frequency and optical functions. Parameter estimation accuracy is heavily related to TbT data quality. BPM faults might lead to erroneous estimation of accelerator parameters and should be accounted for achieving accurate and reliable results. Several anomaly detection methods for TbT data cleaning are considered. Derived features of BPM signals along with their robust dispersion estimation are used to flag faulty BPM signals. Estimated contamination factor is used with unsupervised learning methods (Local Outlier Factor and Isolation Forest). Application of anomaly detection methods for the VEPP-4M experimental TbT data is reported., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

VEPP-4M is an electron positron collider equipped with the universal KEDR detector for HEP experiments in the beam energy range from 1 GeV to 6 GeV. A unique feature of VEPP-4M is the high precision beam energy calibration by resonant polarization technique which allows conducting of interesting experiments despite the low luminosity of the collider. Recently we have started new luminosity acquisition run above 2 GeV. The hadron cross section was measured from 2.3 GeV to 3.5 GeV has been done. The luminosity run for gamma-gamma physics has been started. The luminosity at ψ(1S)-meson has been obtained. For the beam energy calibration the laser polarimeter is used. The paper discusses recent results from VEPP-4M collider., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

VEPP-4M is an electron positron collider equipped with the universal KEDR detector for HEP experiments in the beam energy range from 1 GeV to 6 GeV. A unique feature of VEPP 4M is the high precision beam energy calibration by resonant polarization technique which allows conducting of interesting experiments despite the low luminosity of the collider. Recently we have started new luminosity acquisition run above 2 GeV. The hadron cross section was measured from 2.3 GeV to 3.5 GeV has been done. The luminosity run for gamma-gamma physics has been started. The luminosity at Y(1S) meson has been obtained. For the beam energy calibration the laser polarimeter is used. The paper discusses recent results from VEPP 4M collider., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

Turn-by-turn (TbT) beam centroid signals can be used to evaluate various relevant accelerator parameters including betatron frequencies and optical functions. Accurate estimation of parameters and corresponding variances are important to drive accelerator lattice correction. Signals acquired from beam position monitors (BPMs) are limited by beam decoherence and BPM resolution. Therefore, it is important to obtain accurate estimations from available data. Several methods based on harmonic analysis of TbT data are compared and applied to the VEPP-4M experimental signals. The accuracy of betatron frequency, amplitude, and phase measurements are investigated. Optical functions obtained from amplitudes and phases are compared., Proceedings of the 27th Russian Particle Accelerator Conference, RuPAC2021, Alushta, Russia

The unique feature of the VEPP-4M electron-positron collider is wide energy range (1 - 4.75 GeV) available for experiments in high-energy physics. Energy spread value of the beam is an important parameter in a choice of energy step during measurement of e⁺e⁻ -> hadrons cross sections as well as it has a strong influence on the statistic collection time required for the scanning of narrow resonances like planned for the nearest future scan of Upsilon(2s) meson. Thus, it is important to control energy spread of the beam and measure it operatively and reliably. The paper presents measurements of the beam energy spread at the VEPP-4M electron-positron collider in its complete energy range. Energy spread was calculated from bunch length measured by "PS-1/S1" streak camera with picosecond temporal resolution. In order to exclude the influence of collective effects on bunch length, we measured length of low-intensity bunch. Values of energy spread calculated from bunch length were checked by the measurements of energy spread based on registration of beam decoherence. The impact of the Touschek effect in the beam energy spread at low energy range (1.0 - 1.5 GeV) is discussed., Proceedings of the 26th Russian Particle Accelerator Conf., RUPAC2018, Protvino, Russia

The next phase of the e⁺e⁻ collider VEPP-4 (Budker INP, Novosibirsk) is focused on experiments in the energy range from 4 to 10 GeV (c.m.). To recover the lack of positrons at high energy a new positron source was connected to the collider. The paper discusses the facility performance with new injection and other aspects of experimental study at high energy including laser polarimeter for precise energy calibration., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The paper presents measurements of the longitudinal broadband impedance and beam energy spread of the beam at the VEPP-4M electron-positron collider in an energy range of 1.0 - 3.5 GeV. In order to measure the longitudinal bunch size at various beam currents we used PS-1/S1 streak camera with picosecond temporal resolution. The dependence of bunch length from the bunch current at different energies demonstrates a microwave instability threshold. The bunch lengthening was caused by potential well distortion as well. Potential well distortion lengthening was used to estimate a value of the reactive part of the longitudinal impedance of the vacuum chamber of the collider Observed microwave instability thresholds was used to measure the value of the broadband impedance. The impact of the Touschek effect in the beam energy spread is discussed., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The method to preserve the electron beam polarization on the VEPP-4M storage ring during acceleration with crossing the integer spin resonance energy E=1763 MeV is described. It is based on the use of the non-compensated longitudinal magnetic field of the KEDR detector. This method has been successfully applied for the needs of the R measurement experiment., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

A program code TrackKing for a 6D fully-coupled particle tracking in circular accelerators has been developed with the usage of parallel computations on Graphics Processing Units (GPU) with Compute Unified Device Architecture (CUDA). We can track several thousands of particles in parallel providing optical functions calculation, dynamic aperture and energy acceptance study, intrabeam scattering, radiation effects (including their realistic distribution along the lattice), etc. In the paper we discuss the code arrangement and compare its performance with PTC module of MAD-X., Proceedings of the 12th Int. Computational Accelerator Physics Conf., ICAP2015, Shanghai, China

A design of beam optics will be presented for the FCC-ee double-ring collider. The main characteristics are 45 to 175 GeV beam energy, 100 km circumference with two IPs/ring, 30 mrad crossing angle at the IP, crab-waist scheme with local chromaticity correction system, and "tapering" of the magnets along with the local beam energy. An asymmetric layout near the interaction region suppresses the critical energy of synchrotron radiation toward the detector at the IP less than 100 keV, while keeping the geometry as close as to the FCC-hh beam line. A sufficient transverse/longitudinal dynamic aperture is obtained to assure the lifetime with beamstrahlung and top-up injection. The synchrotron radiation in all magnets, the IP solenoid and its compensation, nonlinearity of the final quadrupoles are taken into account., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

At present the VEPP-4 storage ring facility provides varied experimental programs including HEP, nuclear physics, synchrotron radiation, polarized electron/positron beam research, etc. Until now, the studies were mainly performed at the beam energy below 2 GeV but a strong interest of experimentalists encourages us to increase the beam energy up to 5 GeV. Reliable and high-performance operation at high energy is a challenge for the machine. Here we discuss the recent experimental results at the low energy, and prospects and constraints of the energy ramp., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

An ultra-low emittance lattice based on the ANKA ring geometry is under investigation in framework of the feasibility studies for a compact low emittance synchrotron light source at the Karlsruhe Institute of Technology (Germany). An attempt to apply the concept of split bending magnets cells and to reduce the natural emittance of the bare ANKA DBA lattice from 90 nm×rad down to 2.5 nm×rad with not-vanishing dynamic aperture is described in this paper. The TME cell with split bends and a quadrupole lens in-between as well as a pair of non-interleaved sextupole lenses separated by “—I ” unit transfer matrix of betatron oscillations allows to decrease the theoretical minimum emittance of ANKA ring down to approximately 6 nm×rad. Further reduction of the phase space volume requires to brake “—I ” symmetry and add extra families of sextupoles, locate an additional high order field elements inside the quadrupoles, optimize the phase advance between sextupole families, shift the betatron tune point, enlarge the sextupole strength and other measures. Results of simulations are reported., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

A program code for 6D tracking has been developed taking into account IBS (Intra-Beam Scattering) and Touschek effect and using Monte-Carlo method. The simulation algorithm has been developed on the basis of well-known IBS theory presented in (*). The resulting program can be executed using GPGPU devices (General-Purpose Graphics Processing Units) supporting CUDA technology (Compute Unified Device Architecture)., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

The SuperB project is an international effort aiming at building in Italy a very high luminosity e⁺e⁻ (10³⁶ cm⁻² sec⁻¹) asymmetric collider at the B mesons cm energy. The accelerator design has been extensively studied and changed during the past year. The present design, - based on the new collision scheme, with large Piwinski angle and the use of ’crab’ sextupoles, which has been successfully tested at the DAΦNE Phi-Factory at LNF Frascati, - provides larger flexibility, better dynamic aperture and in the Low Energy Ring spin manipulation sections, needed for having longitudinal polarization of the electron beam at the Interaction Point. The Interaction Region has been further optimized in terms of apertures and reduced backgrounds in the detector. The injector complex design has been also updated. A summary of the design status, including details on lattice and spin manipulation will be presented in this paper., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

The beam is injected into the CLIC damping ring with the relatively large emittance and energy spread and then is damped to the extremely low phase volume. During the damping process the betatron frequency of each particle changes due to the space charge tune shift and nonlinear dependence of the betatron tune on the amplitude. This nonlinearity is produced by the strong chromatic sextupoles, wiggler nonlinear field components and, again, by the space charge force. During the damping, the particle cross resonances, which can trap some fraction of the beam, cause the loss of intensity, the beam blow up and degrade the beam quality. In this paper we study the evolution of the beam distribution in time during the damping for the original lattice of the CLIC DR (May 2005). Geneva, Switzerland June 2010 CLIC – Note – 850

The Super-B asymmetric e⁺e⁻ collider is designed for 10³⁶ cm⁻²sec⁻¹ luminosity and beam energies of 6.7 and 4.18 GeV for e⁺ and e-, respectively. The machine will have the High and Low Energy Rings (HER and LER), and one Interaction Point (IP) with 60 mrad crossing angle. The INFN-LNF at Frascati is one of the proposed sites, and a lattice for short 1.3 km rings fitting to this site has been designed. The two rings are radially separated by 2 m except near the IP and in the dogleg on the opposite side of the rings. The injection sections and RF cavities are included. The lattice is optimized for a low emittance required for the desired high luminosity. Final Focus chromaticity correction is optimized for large transverse and energy acceptance. The "crab waist" sextupoles are included for suppression of betatron resonances induced at the IP collisions with large Piwinski angle. The LER spin rotator sections provide longitudinal polarization for the electron beam at IP. The lattice is flexible for tuning the design parameters and compatible with reusing the PEP-II magnets, RF cavities and other components. Design criteria and details on the lattice implementation are presented., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan

Compact low emittance lattice cell providing large dynamic aperture is essentual for development of extremely low (pm range) emittance storage rings. As it is well known, a pair of identical sextupoles connected by a minus-identy matrix transformer in ideal case of kick-like magnets provides infinite dynamic aperture. Though the finite sextupole length degrades the aperture, it is still large enough, and in this report we discuss development of the low emittance lattice cell providing the -I condition for both horizontal and vertical chromatic sextupoles. Such cell can be used as a module for lattices of different emittance and length. As an example we develop a 3 GeV 10 pm emittance storage ring and study its transverse dynamic aperture., Comment: 8 pages, 13 figures

Recently the peak luminosity achieved on the DAΦNE collider has been improved by almost a factor 3 by implementing a novel collision scheme based on large Piwinski angle and Crab-Waist. This encouraging result opened new perspectives for physics research and a new run with the KLOE-2 detector has been scheduled to start by spring 2010. The KLOE-2 installation is a complex operation requiring a careful design effort and a several months long shutdown. The high luminosity interaction region has been deeply revised in order to take into account the effect on the beam caused by the solenoidal field of the experimental detector and to ensure background rejection. The shutdown has been also used to implement several other modifications aimed at improving beam dynamics: the wiggler poles have been displaced from the magnet axis in order to cancel high order terms in the field, the feedback systems have been equipped with stronger power supplies and more efficient kickers and electrodes have been inserted inside the wiggler and the dipole vacuum chambers, in the positron ring, to avoid the e-cloud formation. A low level RF feedback has been added to the cavity control in both rings., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan